Antropoceno XXIX – Sintese sobre Fronteiras do Planeta

30/11/2015 Pedro Pereira Leite Deixe o seu comentário

Synthesis and progress on planetary boundaries

The science on planetary boundaries builds on the remarkable advancements in Earth system science over the past 20 to 30 years. It’s an integration in the natural next step in scientific advancement between our understanding of the pressures of the Earth system, how the Earth system is a complex self-regulating biogeochemical physical system, and the recognition that if we push environmental systems too far, we risk crossing tipping point that can fundamentally, abruptly, and irreversibly push ourselves away of the stable desired state of planet Earth.

What may surprise you is that the approach of finding planetary boundaries is illustrated very nicely in this first slide here where a Moon lander is looking at our wonderful, small, little marble Earth planet from a distance.

In fact, that’s how the analysis starts. We step out as humanity and try to understand the Earth system and ask ourselves to question what are the Earth system processes that regulate the stability and the resilience of the Earth system? And for each such process we ask ourselves what is the boundary beyond which the system could be pushed outside of a desired state?

And science shows very clearly that we know what this desired state is. And in this slide as a synthesis of that shows the ice core data from Greenland indicating the enormously jumpy ride that humanity has had throughout his entire period on Earth as modern human beings.

This graph shows our last 100 000 years journey on Earth, until we enter the final, last interglacial period, which we learned in school to call the Holocene, which I would call the Eden’s Garden, the perfect paradise, desired conditions for us to build our civilizations and the modern world as we know it.

So the planetary boundary framework is about safeguarding the desired Holocene-like state on Earth by recognizing this state as the only state we know that can support the modern world as we know it, and from science determining the Earth system processes that regulate this state.

And that is what led us to defining the nine Earth system processes that we know, with the best science at hand, regulates the stability of the Earth system.

And here we have of course the big systems with large scale tipping points, such as: climate change, ocean acidification, stratospheric ozone depletion. We have the four slow variables that operate under the hood of the Earth system regulating the ability of the large systems to be stable: land system change, fresh water use, the rate of biodiversity loss, and the way we interfere with the large nutrient cycles of nitrogen and phosphorus. And then we have the two processes that are so highly manmade: namely aerosol loading, which is all the soot and the particles in the atmosphere that cause large health challenges but also influences, for example, rainfall patterns and weather conditions; but finally of course the novel entities, the exponential growth of chemical compounds that aggregate themselves in the Earth system.

By tapping on the best science we can put quantitative boundaries that gives us in green a safe operating place. This is where we can put humanity back, to prosper, develop, evolve, and thrive within this safe operating space. That’s why planetary boundaries is a truly integrated analysis. It’s about a safe space, and by biophysical terms, but it’s about recognizing equity, fairness, and a just distribution of the remaining ecological space on Earth to enable a world of soon 9 billion people to develop and prosper.

In my mind this is the new definition of sustainable development. It’s recognizing that global sustainability and development within a safe operating space is the new endeavor and the new goal for human development on Earth.

We’re very excited by the fact that science can now step up to, I would argue, the responsibility of providing quantitative global environmental goals of this kind. It shows in our analysis that we’re already in a danger zone on climate change, biodiversity loss, and interference with the nutrient cycles.

This work was released the first time in 2009, and has since then led to a very large, vast set of scientific efforts of critically analyzing the quantifications, critically asking the questions whether we’ve got the nine boundaries right, and based on all the science we are working continuously updating this concept to get the absolutely best quantifications.

And a few exciting updates have occurred based on scientific colleagues around the world publishing updated work in this area. The first one is the recognition that the nine boundaries are not entirely, so to say, even in the role of regulating Earth resilience.

In fact we do identify now that three of the boundaries are what we call core boundaries. They operate and regulate the entire Earth system, and they are the endpoint depending upon how the other boundaries operate.

So the best example of these three core boundaries is climate change. Climate change is the end result of how we manage fresh water, nitrogen, phosphorus, land, biodiversity, oceans. It all aggregates up into the functioning of the climate system. So when we use climate forcing as a good control variable for the climate system, the level of that forcing, whether or not we stay within the boundary, depends intimately whether we’re able to stay within a safe operating space for the other boundaries, to the extent, in fact, that among us scientific colleagues we talk of the boundaries as being like three musketeers, “One for all, all for one.” It seems we need to stay within a safe operating space for every boundary in order to avoid that one boundary flips over across the threshold.

The other core boundary is biodiversity. We now recognize increasingly that the genetic diversity on Earth, and the functions they play to sustain resilience and to build human well being, is a high level aggregate result of how we manage fresh water, land, oceans, nutrients, and even the climate system.

And the third core boundary we believe is novel entities. The reason for this is that chemicals, such as everything from endocrine disruptors, persistent organic polluters, all the way to nuclear waste and loading of heavy metals, is so totally lien to the operations of the Earth system, in fact the Earth system has never seen, at least not in millions of years, the kind of human-induced artificial loading of new totally artificial compounds into the Earth system.

We’re learning as we speak what the aggregate effect of these can be on our own health, on the genetic composition of species, from birds to humans. But this is an entity of its own core right. And these three we call core boundaries.

The second development is that we’ve refined the biodiversity boundary. We call it now biosphere integrity, because we recognize that genetic diversity is one thing which we captured in the first analysis. Basically what’s the number of species on Earth, which we can measure quite well with extinction rate, which you used in the original analysis.

Now we’re much more, let’s say, sophisticated in using a new index called the biosphere integrity index, which measures not only number of species but also their functions and how many species within each function. So we can secure, for example, that we do have the minimum amount of pollinators in an agricultural landscape. And this is truly exciting giving the tools for sustainable development in the Anthropocene.

We’ve also refined some of the quantifications. And I would just like to share a few of the key developments here. And the number one is on phosphorus. In the original analysis, we were preoccupied with how much phosphorus can we load into the oceans before we risk a large scale tipping point in the oceans into anoxic, oxygen-free dead states in the ocean?

We were criticized for this. Scientists pointed out that way before you’ve pumped in so much phosphorus in the ocean that you could tip the ocean you’ve destroyed so many fresh water systems along the way of the journey of phosphorus from where it’s loaded, often in an agricultural field, to the ocean that we have tipping points occurring in fresh water systems. So now we actually have a twin definition of the phosphorus boundary.

One, which we maintained from the original analysis, which is the amount of phosphorus that we can load in the oceans. It emains in fact eleven million tons of phosphorus per year. We’re today loading eight, nine so we’re approaching the boundary. But can you imagine? The analysis shows that already at averaging at 4 million tons of phosphorus per year on what we call erodible soil, which is essentially how much phosphorus we can load on productive agricultural land, when we go beyond that number we risk large scale tipping points in fresh water systems. These twin boundaries need to be considered for phosphorus.

For nitrogen finally we took, which was a very wise decision, the valve of how much inactive nitrogen we can maximum take out of the atmosphere, and transform into reactive nitrogen which would plug into the biosphere. You may be aware that the fantastic invention of the Haber Bosch process, which produces reactive nitrogen fertilizers is the vehicle for our modern agriculture, without which we probably could not feed ourselves in the modern world. But it loads reactive nitrogen into the biosphere at an extent, which is so large that we humans are now a much larger force than the entire global natural nitrogen cycle.

We estimated in the first analysis that the maximum loading of nitrogen in order to avoid that nitrogen triggers tipping points in ecosystems was 35 million tons of nitrogen per year. It was a first best guess. Roughly one-fifth of the amount of nitrogen that we’re taking out of the atmosphere, so a dramatic decrease, and therefore indicating that we’re way out in a danger zone on nitrogen.

However, we did, you could argue, a simplification in the first analysis, because you see there’s another way that we humans take out nitrogen from the atmosphere, which is by cultivating nitrogen-fixating crops. So, we have also biological fixation nitrogen actively induced by us humans in modern agriculture. Now we have included that, so now we have a boundary that includes both the industrial uptake of nitrogen from the atmosphere in the industrial production of fertilizers, and the additional human-induced nitrogen fixation by, for example, legumes in modern agriculture. And together that forms a much more robust boundary, which ends up being an estimated 44 million tons of nitrogen as a maximum boundary per year.

I won’t go through the rest of the boundaries. I really urge you to look at the analysis and the materials that come with this lecture. But I really want to close by emphasizing that every boundary has an uncertainty range. And the uncertainty range is often quite large. It’s the humble reminder that science continuously adds new knowledge, and that the boundary position is proposed at the lower, more precautious end of that uncertainty range, because we now, as for ozone, that we always are facing surprise when it comes to the large changes we’re seeing in the Anthropocene.

Overall it’s also important to recognize that even though we have attempted to quantify boundaries for the nine boundary processes at the global level, they do operate across scales, and they do interact across scales. We’ve done some very significant updates in terms of downscaling those boundaries that are relevant to downscale, and these include, for example, the coupling of a global boundary, on fresh water with the river basin definition of minimum amounts of environmental water flows.

The coupling of the phosphorus boundary for fresh water, with a maximum amount of phosphorus per hectare of land that we can allow ourselves to apply. Same for nitrogen, taking it down to the hectare level.

These are really exciting developments which enable the planetary boundary concept to be operational also at the local level, for a business, of a community, or of a nation’s policies in terms of how to contribute to stay within a safe operating space. And that is in my mind one of the biggest advancements in the work we’ve done in the planetary boundary analysis over the past five years.

Bilhetes, Lectures / Readings

Antropoceno XXVIII – As novas fronteiras

30/11/2015 Pedro Pereira Leite Deixe o seu comentário

Novel entities

Hello, my name is Sarah Cornell and I’m an environmental researcher at the Stockholm Resilience Centre. The first thing I need to do right now is explain what I mean by the term novel entities. Back in 2009, Johan Rockstrom and colleagues argued that there should be a planetary boundary for chemical pollution. But they weren’t able to define a quantitative value for that boundary. 551

In recent years this challenge has been a topic
of a lot of conversation between Earth system scientists, my own field of research, and ecotoxicologists, people who deal with the problems of chemical pollution.

We now refer to the process as the release of novel entities into the environment. Why did we change the name? Well, first of all it signals that we’re focused on the role of human-caused changes in the Earth system that can fundamentally alter the way that biogeochemical, ecological and physical processes happen at the global level.

The changes we’re concerned about are the ones where human technological capability lets us bypass the normal ecological and physical self-correcting, co-evolutionary behavior of living organisms interacting with the physical processes of the planet.

When I talk about self-correcting behavior I simply mean that the toxic substances that exist in nature generally break down in nature. To give a really blunt example, an organism will die if it’s exposed to natural toxic substances, but natural processes will also tend to break down and disperse the toxin in question. And there are many chemicals that have toxic effects, some of them like salt, or alcohol, or kerosene, or snake venom can be very toxic indeed, but they are dissipated in the environment because living organisms have co-evolved with the processes, the chemical processes, that produce them.

Our human technical capability lets us put together chemical substances in combinations that did not exist before, and that no ecosystem has been adapted to, or can adapt to, on the time scales that we see for technological change.

Chemical toxicity on its own isn’t necessarily the problem, it isn’t a systemic or planetary problem. Life can and does adapt to toxic substances. And we don’t need a planetary boundary for issues that are local and temporary.

We’re concerned about Earth system processes. So for that reason the term chemical pollution was too general for our purposes. But we do need to be aware of the planetary risks of creating these fundamentally novel substances that can’t be metabolized, that don’t break down easily in the environment, and that interfere with the physical and ecological processes on which all of the other Earth system functioning depends.

We’re concerned about humanity’s capacity to mobilize some natural toxic substances in new ways, in new forms, and in an ever-accelerating rate. The most obvious category of novel pollutants is the completely new synthetic substances. We can’t say that there’s a Holocene background level for these kinds of compounds. Compounds like persistent organic pollutants for instance, often called POPs.

Another Earth system problem is the production and the environmental release of highly reactive molecules that contain some of the toxic or radioactive heavy metals. These organic compounds can be transported through water and the atmosphere to some of the most remote parts of the Earth system. Mercury is one very concrete example. Volatile organomercury compounds are emitted into the atmosphere and they can be transported and they expose ecosystems, and human populations, to very high levels of pollution very far away from their original sources.

Here we have a few other examples where Earth system functioning has already been impacted by human technological capability to produce new chemical substances. They’ve all had serious, if not necessarily catastrophic yet, impacts. You’re probably familiar with the problem of the chlorofluorocarbons, the CFCs, that led to the depletion of atmospheric ozone in the upper layers of the atmosphere.

They’re also powerful long-lived greenhouse gases, so in that sense they’re chemical substances that interfere with the physical functioning of the Earth system.

Another very well known example is the problem of DDT, a synthetic pesticide that kills agricultural pests and mosquitoes, but many other organisms too. DDT accumulates in fatty tissues and so it can be carried through the food chain. It persists for years in soils and sediments. It has now become a globally distributed problem and it has fundamentally changed the way that ecological processes happen in the Earth system.

As a result of planetary experiments like these we know that particular traits make novel entities a problem in the Earth system. Toxicity is important but we must take a big picture view that goes beyond just the effects on individual organisms through to ecosystems and actually the whole planet. Problem substances persist in the environment. This means that they can be transported large distances around the world, either in living organisms or through water in the atmosphere. We see systemic effects when these substances accumulate in living tissue. For instance, the problem of bioaccumulation makes substances become more concentrated as you work up the food chain. So, some of our keystone species in ecosystems are the ones that are most vulnerable.

Another important trait in this is the very high risk of irreversibility. Sometimes this is just because a problem has become globally distributed and we can’t deal with it directly, but in other ways it’s because we have passed a physical or an ecological tipping point in the way that the Earth system functions.

All of this means that we are still no closer practically to achieving a single quantitative boundary value for chemical pollution or these other novel entities. A major practical obstacle is the sheer variety of chemical substances, of radioactive substances, and of the many forms that these substances take once they’ve been released into the environment and are subject to chemical and biological changes.

Because of this colleagues at Stockholm University, and many places around the world, are working on defining principles that will let us identify planetary risks associated with the creation of these novel entities and their release into the environment.

We really want to improve the way that we screen for hazards, and the way that we manage and monitor environmental changes caused by novel and synthetic substances in the environment. One of the big implications of this is that we simply must halt the environmental release of the most problematic substances.

556 The big challenge is we don’t know which those substances are usually until it’s too late and the impacts are already seen in the environment. So this also means that we must apply the precautionary principle much better.

The risks of environmental change are not known very often with some of the compounds that we’re creating, and certainly with many of the compounds and technologies that we’re capable of creating. We, here at SRC, and in many of our global change partner organizations, [are] encouraging dialogue about this new area of research.

It requires new interactions between science, and policy, and business, and actually between everybody in society, because we’re all exposed to these new global risks and we need to deal with them together.

Bilhetes, Lectures / Readings

Antropoceno XXVII – A fronteira dos aerosóis

29/11/2015 Pedro Pereira Leite Deixe o seu comentário

Aerosol loading

Hello, I’m Sarah Cornell from the Stockholm Resilience Centre. And I’m going to explain why we’re concerned about the global human impact on atmospheric aerosols.

Aerosol is a rather technical term to describe the phenomenon of liquid droplets or particles, very small particles, that are held suspended in the atmosphere. Aerosols play many very important roles in the atmosphere and in the Earth system.

They can both absorb and reflect light, so they’re important in Earth’s heat balance, and in the climate system. They provide condensation nucleus points; water condenses on aerosol particles and affects where clouds are formed and where rainfall happens. And they also provide microsurfaces for chemical reactions in the atmosphere. So, they influence atmospheric chemistry. For example, the reactions leading to stratospheric ozone depletion, or the ozone hole, happened on polar clouds that formed on stratospheric aerosols in the upper atmosphere.

To understand atmospheric aerosols, and the additional loading that humans are creating, we take physical and chemical measurements of gases, of particles, and of rainfall. A lot of this work is done in particular locations in different ecosystems, especially in urban ecosystems where the particulate loading is highest. But we can also measure aerosols from space.

Aerosols can be emitted directly into the atmosphere and they can also be formed through chemical processes in the atmosphere. That’s what we call secondary aerosol. One of the main natural sources of aerosol is actually the world’s oceans, waves and bubble bursting eject saltwater directly into the air and the water evaporates and leaves little microcrystals of salt. Other natural primary sources include fire, volcanoes, and air-blown dust.

There are natural sources for secondary aerosol too. For example, plankton and land vegetation emit organic compounds that react in the atmosphere to make very small particles. These reactions that create aerosols that affect the distribution of clouds over forests and coastal zones.

We also see human impacts in both direct and secondary aerosols. Land use change and combustion processes change the global patterns of dust and smoke emission. And together with transport and industrial processes we are currently changing the emissions of a very large number of chemical precursor gases that become aerosols in the atmosphere.

You’re probably familiar with some aerosol systems already. Smoke is a suspension of carbon particles in the air; fog is a suspension of water droplets; and the gas emissions associated with human activities, interact with each other and with these natural systems, creating really much more complex aerosol systems like smog and photochemical haze.

In the last century killer smogs, or pea soupers, were a severe environmental problem, so industrial smoke emissions are very tightly controlled in many cities of the world. But however industrial and urban emissions are still the cause of many problem aerosols in other parts of the world.

Photochemical haze plagues cities like Shanghai and Los Angeles and many other mega-cities in the world.

These aerosol systems are complex. They involve both natural and anthropogenic sources, they involve many different kinds of chemical substances, they involve direct emissions and reactions that happen in the atmosphere, and these reactions involve solids, and liquids, and gases. In other words, the composition and the ultimate fate of aerosols depend on many different geographic and meteorological conditions.

This presents a major challenge to us when we’re trying to find a global measure for what is acceptable or not acceptable in terms of aerosol changes in the Earth system. On top of that the world’s ecosystems on land and in the oceans have evolved and adapted to the biogeochemical flows that aerosols provide.

The human impact isn’t just as simple as an increase in aerosol loading. In some instances human activities are removing or relocating aerosols. We risk setting off physical and ecological tipping points when we change atmospheric chemistry in this way. This animation shows the global patterns and total aerosol loading of the atmosphere. It’s clear that aerosols are a vital part of the Earth system, and a dynamic part, and also that there’s a huge amount of variability in their local and regional patterns.

This figure is from the Intergovernmental Panel on Climate Change, and it shows the complex effect of atmospheric precursor gases in the top of the red box, and aerosols in the lower part of the red box. It shows the effects of aerosols and gases on Earth’s radiative balance. Some have a positive effect on radiative forcing, leading to warming of the atmosphere; and others have a negative forcing, in other words they lead to cooling. The net global effect is a cooling, at the moment.

The climate planetary boundary already addresses the radiative forcing effect of aerosols. But there are good reasons to address anthropogenic aerosol directly in the planetary boundaries concept, in ways that address their physical and biogeochemical impacts, not just their effects on the global energy balance.

In this context it’s really important to recognize the regional complexity of aerosols. One example where humans are causing regime shifts that might affect the whole Earth system is the change to the Asian monsoon system caused by the intense brown cloud of atmospheric pollution over south Asia and the Indian Ocean.

Another is the change in tropical rainfall patterns caused when deforestation reduces the natural aerosol emissions from trees and its interaction with the water cycle. This change can trigger climatic and water cycle feedbacks that would accelerate regime shifts or tipping points from forest to grasslands.

And yet another example that can trigger climate and ecosystem feedbacks is the deposition of dark aerosol particles, soot, or black carbon, on ice sheets and glaciers, accelerating their melting.

These kinds of pollution changes affect the regional albedo, and result in shifts in weather patterns, and biogeochemical flows, and ecosystems and the biodiversity within them.

In summary, although there is no single value for a planetary boundary that incorporates all kinds of aerosols all around the world, there’s a very strong case for specific sub-boundaries to be defined for particular aerosol systems in order to maintain the functioning of global earth system processes.

Lectures / Readings

Antropoceno XXVI – A fronteira do ciclo do Fósforo e do Nitrógeneo

28/11/2015 Pedro Pereira Leite Deixe o seu comentário

Interference with global n and p cycles

I’m going to talk with you about human impacts on the global nitrogen and phosphorus cycles.

The global biogeochemical cycles link the living and the non-living parts of the Earth system. Chemical relationships control the general patterns of interaction between geological and biological processes. It’s the way that the nutrient elements flow through land, ocean and atmosphere that ultimately regulate all of life on the planet. And human activities are changing all of these basic cycles.

As we explore this topic, I’ll make reference to very simplified diagrams like this one, that show the present day cycles and the human changes. The arrows just show the overall annual flows of the elements between the Earth’s crust, atmosphere, oceans and the biosphere, that is all the living organisms on Earth.

It’s important to keep in mind that these flows are the result of many different Earth system processes, and at the same time it’s also important to remember that in the boxes, atmosphere, ocean, biosphere, and so on, we see many processes and feedbacks happening all the time. The Earth system is a very dynamic system, and the simple diagram is a very simple representation.

Because all of these boxes are connected to each other through these different processes, human activities in one will play out in all of the others. It’s these consequences that mean that we need a planetary boundary for nutrient elements.

Piecing together the global budgets, in other words putting the numbers on the up and down arrows in those diagrams, is one of the major achievements of the last 50 years. It takes international and interdisciplinary research, and it involves scientists working in all kinds of environments around the world.

People are most familiar with the global carbon cycle because changes in carbon are so tightly linked to the climate system. The figure shows some of the processes that are happening at the moment. And here is the first of the simple flow diagrams I talked about.

The numbers show the annual flows between the different stocks of carbon in the Earth system, and the red arrow shows the human disturbance. Every year the biggest single change that we make to the carbon cycle is that we’re moving carbon from underground fossil fuel stocks into the atmosphere.

We also contribute carbon dioxide into the atmosphere through deforestation and agriculture. But our main concern is that this carbon dioxide is accumulating in the atmosphere where it acts as a greenhouse gas. Climate is changing as the concentration increases.

But carbon isn’t the only element that we’re changing. People are much less familiar with the other elemental cycles, but they’re just as important, and actually they’re tightly linked to carbon and the climate system too.

In this picture you can see the main changes in the nitrogen cycle. Nitrogen is one of the essential elements that sustains all of life on Earth. We use it in our proteins that make up our muscles, for example. The flow diagram shows the natural changes in white and the red arrows show the major changes that humans are causing in the system. The biggest change is the transformation of atmospheric nitrogen into reactive forms, like nitrate and ammonia. We do this because we need that nitrogen as fertilizer for the food production.

We also fix nitrogen from the atmosphere through many other processes, industrial processes and transport as well.

Right now the red arrow of nitrogen fixation is bigger than the natural arrow of natural biogenic fixation of nitrogen. We are currently more than doubling the natural rate of drawing down of nitrogen from the atmosphere into the biosphere, but you can see that that isn’t all that we’re doing. This nitrogen is not all taken up by crops. A large amount is being released back into the atmosphere where it causes air pollution problems and acid rain, and is a climate greenhouse gas, and the rest is released into rivers and oceans where we have problems of nitrogen enrichment and eutrophication. I’ll explain what that is in a little while.

This is happening all around the world. When rivers, lakes, and coastal zones have very high concentrations of nitrogen, and other nutrient elements, the most responsive organisms draw up this nutrient most quickly. We end up with algal blooms, microorganisms are thriving in these water conditions.

The image shows areas where there are very large amounts of marine algae, reflecting the highest concentrations of nutrient elements.

In the nitrogen cycle we have another particular challenge, which is that a large amount of the nitrogen is transported all around the world, very large distances, in the atmosphere. We see biogeochemical and ecological tipping points in area far away from the most intense sources. The densely populated areas have the most intense nitrogen pollution problems, but you can see from the figure that in this century of industrial activity, nitrogen really has become a global problem.

The issue is not just a regional one. And nitrogen is not the only element that’s causing us concern at the moment. The phosphorus cycle is also being changed very substantially by human activity, and phosphorus is another one of these essential nutrient elements.

The figure again shows the processes that are happening in the Earth system, and the simple diagram shows the natural flows in white and the major human perturbation in red. Unlike nitrogen and carbon, phosphorus isn’t really affecting the atmosphere. The biggest change is that human activities are mining it from the ground and applying it to land surfaces for agriculture, 25 million tons a year. But a large amount of this phosphorus is being mobilized in the Earth system through the watercourses. It goes into our rivers and receiving oceans. It also contributes to nutrient enrichment. Nutrient enrichment doesn’t really sound like a problem, but it is a very serious one. Locally it’s a major problem for public health and environment, and it’s an economic issue as well.

In nutrient-enriched water systems biodiversity typically decreases. And when the algal blooms die and rot away they starve the water of oxygen. We end up with dead zones, and this is another example of tipping points that we see in the environment. It’s the risk of large and irreversible dead zones in the oceans that really calls for a planetary boundary for phosphorus.

The changes in both the nitrogen and phosphorus cycles are largely driven by the same human activity. In other words, fertilizer application for food production. The global impact arises from regional activities, so a really major area for research and policy at the moment is to improve the global assessment of both these nutrient elements.

The planetary boundaries for human interference in the global nutrient cycles now reflect these regional differences. The ecological impacts of the eutrophication of surface waters, and increasingly we’re working on trying to improve the links between the elemental cycles because they’re linked in nature.

Bilhetes

Antropoceno XXV – A Fronteira do Terra e da Água

27/11/2015 Pedro Pereira Leite Deixe o seu comentário

Land and water use change

In this lecture we’ll go through two of the slow variables constituting critical planetary boundaries that regulate under the hood of the Earth system the big climate system and the large operation of the global hydrological cycle and how biodiversity can operate in our living biosphere, in land and water.

And we’ll start with land. Can you imagine? Over just the last 150 years we have rapidly moved into a situation where we’ve transformed almost 40% of the world’s land area into urban regions and predominantly agriculture.

And this enormous transition is illustrated through this series of maps showing the development over the last decades. Now for land use the absolute critical issue to recognize is that what determines the ability of land areas to regulate fresh water, regulate flows of different nutrients, be habitats for biodiversity, and regulate fresh water flows, is what kind of ecosystems we have.

And what we’re finding is that the number one biome system to regulate the stability of the Earth system is our forest systems. And in the original planetary boundary analysis we used a proxy to define and safeguard the critical forest areas in the world, namely what was the maximum amount of cropland that we could allow ourselves, because cropland is the largest human-caused land use change on Earth.

And we used it because we have good data on cropland extent and cropland change. Now in the updates that we’re doing we’re focusing much more on what you see on this slide, namely directly analyzing how much of the different critical forest systems do we need to regulate the Holocene stability on planet Earth.

And we’re finding from science that the rainforests in the world, the temperate forests, and the boreal forests are the most critical ones in regulating Earth resilience. Now we are so rapidly changing forest systems in the world.

One very dramatic example is shown here from Borneo, where almost, or a bit more than fifty percent of rainforests have been cut down so far in order to transform land use to large scale palm oil plantations. And you see in this graph the transition of the growth of palm oil and the reduction in rainforest. And this has dramatic effects for local biodiversity, devastating effect for local indigenous communities, but it also directly affects the entire regulation of the climate system and the regional patterns of rainfall across vast areas. So these are truly regulating functions at the planetary scale. And we only have three remaining rainforest areas: the Indonesian, southeast Asian, the Congo Basin in Africa, and the Amazon rainforest in Latin America.

Now the question one asks is do these shifts associate themselves with tipping points? And evidence suggests that the answer to this question is yes. Very rarely or ever in isolation, but land use change can together with changes in fresh water use trigger large scale abrupt and even irreversible shifts; what we call tipping points.

When you change land use we can have so large [a] shift in fresh water flows that it could actually induce tipping points, meaning for example when we cut down forests, take out fresh water in river basins, that we could have permanent tipping points where large tracts of land get locked into desertified states, as one example.

So there are examples of how we can induce tipping points when pushing land and water systems too far. Now nothing is static, and if you load climate change on top of this we see projections into the future that would put even more strain on particularly fresh water systems.

Here you see a very recent analysis by Jacob Schewea and colleagues at the Potsdam Institute for Climate Impact Research trying to analyze what would happen with fresh water resources in the world at 2 degrees C warming, so a point at which we most likely will be quite soon already within this century.

Now if you look carefully at this map you’ll see the red areas in the world where the projections show, when we gather all the knowledge that we have today, regions that will lose 25 or more percent of average annual runoff. And losing so large [a] portion of fresh water resources is truly a risk of crossing tipping points for both ecosystems and food supply will be jeopardized.

So these are examples of moving and the risks we would take if several boundaries move out of their safe operating space, in this case climate, land and fresh water.

So if we move into fresh water and the diagnostic of what makes water a planetary boundary it’s in its fundamental diagnostic the role water plays as the bloodstream of the biosphere. Water regulates everything we know in the biosphere, all vegetation growth, all biodiversity depends on fresh water.

Humans depend on fresh water, and this map shows just the degree of water scarcity in the world as projected until 2025, taking into consideration fresh water considerations in ecosystems and human needs.

So what we’re recognizing increasingly that the global hydrological cycle, which is finite, is fundamentally a prerequisite for the stability of the Earth system: it regulates climate, it regulates biodiversity, and it’s fundamentally important for social and economic development.

Now what makes water so interesting from a planetary boundary perspective is that it flows yearly in its hydrological cycle, evaporating from land and oceans, creating clouds, falling down as rainfall, infiltrating into the soil into what we call green water, the portion of rainfall that forms soil moisture and then flows back into the atmosphere as evaporation and transpiration, totally constituting vapor flows, and one portion flowing off on land and as groundwater flow, what we call blue water, the liquid water that fills up our lakes, rivers, wetlands, and dams.

Now what we’re learning increasingly is that we have to have sustainable management of landscapes at large scale to safeguard rainfall, what we call precipitation sheds, which is what’s the area that we depend upon as a source of our rainfall?

And this is an illustration not only why water is a planetary boundary, because it’s safeguarding the management of the fresh water cycle, from the local watershed scale to the base of the global scale, regulates the entire flow of fresh water which, again, regulates climate and biomass, but also how intimately coupled fresh water is to land management and deforestation.

So these are key justifications from science making water and land so important as planetary boundaries. Now the question is how much water do we need to safeguard in order to stay in a Holocene-like state?

In our original analysis we did this from a global perspective, we looked at the global hydrological cycle, we looked at how much water can we take out in the large basins And biomes of the world before we start seeing evidence of tipping points, and calculated a global number of the maximum amount of water that we can consume in our rivers before we end up with a situation where we could see evidence of tipping points. But we did this from a very global analysis, synthesizing literature.

Now we’re adding a very important piece to the evidence, namely digging ourselves much more down into detail in all the river basins in the world, exploring based on vast amounts of knowledge that is out in the field on how much water do we need to sustain in our rivers to keep ecosystems functioning, what professionals call environmental water flows.

And what you see here in this graph is the latest update of a bottom-up estimate of the global fresh water boundary based on this analysis for every basin in the world, what’s the minimum amount of fresh water we need to sustain in order to keep basins resilient?

And the exciting thing is that we’re now combining these two analyses of a top-down global estimate of the planetary boundary for maximum amount of fresh water use with a bottom-up analysis of how much fresh water must stay in the basins to keep basins, large landscapes operational. And this leads to our estimate of the final planetary boundary.

But before coming to the numbers around where the boundaries land, let me just close with a kind of summary statement with regards to the importance of land and water for the human future on Earth.

We are soon nine billion people on our planet. Everyone with a right to development and the basis for development will be access to food and fresh water. Recent estimates shows [show] that just to feed humanity in a world in 2050 with nine billion people will require potentially an increase of fresh water use from our current 7000 cubic kilometers of fresh water per year, both in irrigation and rain for that culture, to in the order of 9000-10 000 cubic kilometers per year.

This in a planet where already 25% of our large rivers no longer reach the ocean because we’re taking out so much water to produce food. Now the question is can we transition the world on fresh water land within a safe operating space?

And John Foley and colleagues here at the Resilience Centre recently did a very significant synthesis asking this question: can we feed the world within a safe operating space?

And the answer is that yes, in fact we have so many innovations and so much untapped potential to improve the efficiency and productivity of fresh water use that we can in fact attempt to achieve this grand challenge of feeding humanity within a safe operating space. Yes, we are in a very challenging position in terms of sustaining fresh water and land within a safe space. On the other hand we can, within a safe space, also meet demands for a growing population.

In terms of definitions of the boundaries then what we’re done is that the original estimate was to say: what’s the maximum amount of cropland that we can expropriate beyond which we risk tipping risks induced by land use change?

That estimate was set at a maximum cropland extent of 15%, and we have today transformed 12% of the world’s land surface into cropland. It’s 12% for cropland, but it’s forty percent if we include also grazing lands. But we took cropland because that’s a set of data that we have quite a good handle on. In the updates that we’re doing we are, as I mentioned, reversing this to rather say how much forest do we need to maintain in order to sustain Earth resilience? And our estimates show that we need to keep in the order of 75% on average for all the big forest systems, and we are today actually at a situation where we have cut down more Than 25%, we actually only have 62% of forests left on Earth. So we’re already in a danger zone with regard to the planetary boundary on forests.

But importantly we’re actually able today to make the first estimates for how much rainforest we need to keep, and our estimate shows we need to keep 85% of rainforest systems, that we need to keep 50% percent of our temperate forests which play a lesser important role in terms of its total coverage to maintain Earth resilience, and that we need to keep in the order of 85% of our boreal forests to stay within a safe operating space.

And this is a signal or a way of showing that the planetary boundary at the global scale can actually be translated to the operational scale of forest management in large parts of the world. But it does, and I really want to remind ourselves of this, forests do not respect national borders. It shows that it’s a global concern to safeguard the remaining forests on Earth.

Similarly for fresh water we maintain. The original analysis that we need to keep consumptive fresh water at the global scale 4000 cubic kilometers of fresh water per year. That is the boundary that we feel we still have evidence to support. But then we’ve done this bottom-up analysis of the amount of environmental water flow in all the basins in the world, which ends up with an aggregate boundary corresponding to in the order of the same magnitude as our estimates top-down, but it gives us percentages of maximum allowable withdrawable fresh water at each river basin in the world, which ends up in the order of 25 to 50% of fresh water must be kept in the rivers, and that there’s a large variation here is that it depends for each basin on how much fresh water there is, if these are permanent basins, if these are intermediate basins, if these are only infermeral basins, the flux intensity, etc. So there’s a lot of intricacy here but it just shows that we can operationalize this at the level of management.

So overall land and water as fundamental boundaries regulating Earth resilience and our desired Holocene state. They operate at the local level but aggregate into impacts at the global scale, interact very closely with particularly biodiversity and the climate system, and are fundamentally part of the operational management for a sustained prosperous future on planet Earth.

Lectures / Readings

Antropoceno XXIV – A Fronteira da Perda da Biodiversidade

26/11/2015 Pedro Pereira Leite Deixe o seu comentário

Biodiversity loss

It may surprise you that biodiversity is one of the planetary boundaries. But when one sits down and reflects a bit it becomes very obvious that biodiversity must be one of our planetary boundaries.

Think of it, without the living species everything from vegetation, trees to animals and small insects, pollinators, we would have no biomass, there would be no carbon sequestration, there would be no rainfall because a large portion of our fluxes of water originate from the canopy, from vegetation transpiring and evaporating water back to the atmosphere. It regulates the flows of fresh water, regulates the flows of carbon, nitrogen and phosphorus.

The living biosphere is a fundamental component in regulating the stability of the entire Earth system. And this relates to two components. One is the genetic diversity; the treasure of genetic code, which forms the adaptive capacity of the entire Earth system. But it’s also the diversity of functions that we know today that in order to develop, for example, food for a world population of 7 billion people we need the functions and landscapes for pollination, the function of microorganisms in the soil to develop organic matter which in turn delivers nutrients for plants, without which we would have no food.

So we need to explore the functional diversity and the genetic diversity in the rich treasure of living species on Earth. And this forms part of a core fundamental part of a living planet. The drama is that we’re really mismanaging biodiversity in the world. In fact we are today, based on the observations we have, in the sixth mass extinction of species in the world, the first extinction to be caused by another species, and one of these six, for example, being when we lost the dinosaurs 65 million years back on Earth.

So these are big, dramatic changes, illustrated here for example when it comes to how we’re dealing with global fisheries. Just over the past sixty years from the 1950s and the onset of the great acceleration when we started the exponential rise in pressures on planet Earth, you see here the extraordinary social-ecological journey of not only increased landings of fish, but also that fish efforts are changing dramatically from small scale fisheries to large scale industrial fisheries where we are basically vacuum cleaning large tracts of oceans, not only in shallow waters but also in deep ocean regions.

We have the classic examples of collapse of fisheries; like the cod fisheries off the shores of Newfoundland, where we’re learning unfortunately that once we cross a tipping point with regards to loss of fisheries we can actually lock the system in a situation where the fish does not even come back.

So these are big, dramatic changes that we need to incorporate in our understanding of the resilience of the Earth system. We also have interactions between species.

This is an example of how delicate the system works in terms of relationships between seabirds and fisheries. A large synthesis across essentially all marine systems across the world shows that when we overfish and lose more than 30% of fish stocks that has an abrupt impact on seabird populations which go through, and cross a threshold leading to abrupt changes in populations. So loss of one species in this case over-fishing, has a propelling effect on seabird populations which risk collapse, in fact, in many parts of the world.

So again the risk of not connecting diversity in species and thereby not understanding that this can lead to propelling effects across the world. A fundamental, very essential part of our own future is of course the ability to produce food. And there’s another example of how a function in ecosystems simply provides us with a free service, namely pollinating insects.

And here’s one example of a global concern among farmers, scientists, citizens in general, that we’re losing pollinating bees at a very rapid pace, to the extent in fact that some agricultural regions are collapsing. We have human beings have to step in and function as human insects to pollinate apple orchards in China. We have examples of collapse of pollination in some parts of the UK, United Kingdom, because of overuse of pesticides which led scientists to pop over to neighboring countries in Scandinavia and try to borrow bumble bees to be used as pollinators in their own agricultural systems.

So again, understanding that biodiversity – without biodiversity we cannot have modern agricultural systems, and therefore we get locked in an undesired state in terms of delivering human well-being.

So in summary, what occurs is the recognition that biodiversity is fundamental for the regulation of the Earth system, it’s fundamental for human well-being. We tried based on this evidence to identify what could be a good control variable, an indicator for a planetary boundary on biodiversity?

We took as a first starting point an indicator that maps out the rate of extinction, how many species we’re losing, over time. And this indicator called the extinction rate per million species per year, which is a good indicator of the pace of loss of biodiversity.

The natural background rate of loss is roughly one species per million species per year, that’s the normal background rate. We estimate as a first guess that a boundary lies somewhere between ten and hundred lost species per million species each year. So the boundary was placed at ten species lost per million species per year. Now today we’re losing species at roughly ten to hundred times faster that rate. That’s why we can today say with quite a high degree of confidence that we’ve actually transgressed and are in a danger zone on biodiversity.

But we’re also exploring to understand an even better indicator for biodiversity because extinction rate only gives us a measure of diversity, it doesn’t give us any measure of the functions biodiversity plays.

And here I’ve just given one example of how the science it is advancing in terms of mapping out the functions that biodiversity plays for humanity.

This is illustrated from another index that is called the mean species abundance, which is an average measure of not only the number of species in each ecosystem in the world, but also how many in each species group we have grouped in terms of functions.

And here you have a map of the world of the situation, the state for biodiversity in terms of species abundance in the year 2000. And you can see in red the hotspot regions where we are truly in a very risky zone in terms of losing too much of species abundance. But in green you have regions that are still in a safe operating space.

And here you have the projections into the future, up until 2050, of the risks if we do not transgress ourselves, or if we do not move ourselves, into a safe operating space in terms of safeguarding biodiversity.

We’re right now working very actively in improving this analysis even further to say that extinction rate is a good measure of the diversity and richness of species in the world, but we’d like to have a better measure to measure and to determine the functions that biodiversity plays for human well being.

And one of these indices is a very exciting new advancement on something called the biodiversity intactness index, which is an even better measure on functional groups for the role played by ecosystems for human well-being.

And this is something that will be hopefully developed further and much more broadly in the world because so far it’s used in just a few ecosystems in the world.

But overall, in summary, biodiversity as a key for human well-being, biodiversity as a key for regulating the stability in the Earth system.

Science shows clearly that biodiversity is key to regulate a world that remains in our desired Holocene-like state, and science can now put the first quantitative estimates of a safe boundary within which we have a high likelihood of being able to rely on biodiversity, the richness of all species on Earth, as a support for human development.

Lectures / Readings

Antropoceno XXIII – As 4 fronteiras silenciosas

25/11/2015 Pedro Pereira Leite Deixe o seu comentário

In last five posts we’ve gone through the big planetary boundaries of climate change, ocean acidification, and stratospheric ozone depletion. Naw will be covering the remaining six planetary boundaries.

This is a really exciting module where we will be exploring the boundaries on biodiversity loss, freshwater use, land use change, our interference with the global nitrogen and phosphorous cycle, aerosol loading, and novel entities of chemical pollution.

Lectures / Readings

Antropoceno XXII – A Fronteira do Ozono

24/11/2015 Pedro Pereira Leite Deixe o seu comentário

All life on Earth depends on the extraordinarily thin layer of livable atmosphere which envelopes the biosphere in our Earth system. But above the atmosphere in the high atmosphere, roughly ten to fifty kilometers above ground, we have the stratospheric ozone layer.

And the stratospheric ozone layer is a protective shield that enables life on Earth by reflecting back harmful ultraviolet radiation from the Sun. So clearly the ozone layer is a planetary boundary enabling human prosperity and development on Earth.

The stratospheric ozone layer has for a long time been understood as being absolutely essential for living conditions on Earth. And in the early ’80s scientists started to observe something absolutely extraordinary namely a rapid, abrupt drop in the thickness of the ozone layer.

This was a huge surprise, in fact scientists even thought it was an error in the scientific observations. But through fantastic research by top scientists in the interface between atmospheric research and chemistry soon it was proven that the reason for this depletion was that certain chemicals that we used as refrigerants, as solvents, propellants, the whole family of chlorofluorocarbons were moving up the atmosphere through high winds and reacting with ozone and – and breaking these molecules apart and thereby depleting the stratospheric ozone layer, threatening life on Earth, and particularly health for humans, by risks of rising skin cancer, cataracts and damage also on vegetation, food production systems on Earth.

This led in the mid-1980s to the extraordinary step where the world gathered around a protocol, the famous Montreal Protocol, to ban chlorofluorocarbons from use in refrigerators. And this in turn has led to a success story where a boundary of ozone depletion was transgressed in the early ’90s and now we’re actually moving into a safe operating space, showing that humanity in fact can collectively as all nations on Earth work together to operate within a safe operating space.

So we are moving in the right direction on ozone, but what is very important to recognize is that we’re still observing an ozone hole, particularly over the polar regions, and the classic ozone hole is in Antarctica, which is due to the combination of ozone depleting substances, continued emissions of chemicals, but also the fact that the sins of the 1980s are still haunting us because of the delay time in much of these chemical reactions, which is also a reminder that, uh, we need to apply the core thinking of planetary boundary theory which is a precautionary principle, because what we do today, which we sometimes do not even understand, can have a harmful effect on the Earth system, can actually come back and hit us many, many decades later.

I’ll give you a small example that comes from the Nobel Laureate Paul Crutzen, who was one of the three scientists observing the depletion of the ozone layer in the early 1980s. The industry at the time had a choice of two molecules to develop the refrigerating chemicals that were used worldwide, either chlorine or bromine. And just so happened by pure coincidence that the industry chose chlorine. That was very lucky for humanity because it just so happens that chlorine has several magnitudes lower harmful effect on ozone. If the industry in the early ’80s instead has chosen, or rather in the early ’60s all the way up to the ’80s when we banned the chemicals, had chosen bromine as the carrier of refrigerating systems across the world we most likely would have had a catastrophic tipping point that would have undermined human development on Earth.

So that’s an example of how close we were of what we can call a planetary scale disaster, and why thinking in terms of defining planetary boundaries is so essential. Science has come to a point where we are at a position where we can define a control variable, which we have chosen as the thickness of the column of ozone across the planet.

And this gives us a very good, robust, science-based definition of how much we must maintain in terms of ozone, and thereby also translating that to avoiding chemicals that can destroy the ozone layer.

Is the problem finally resolved? Well the answer is unfortunately no. The most damaging chemicals used in the early ’80s are not on the market any longer, but we’re using other types of refrigerants, and methane is a compound that also poses a threat to the stratospheric ozone layer, and we see other emerging novel entities that could actually threaten the ozone layer, reminding us that planetary boundary processes do interact, and one very strategic way of protecting the ozone layer is also to have a strong boundary on chemical pollution.

Lectures / Readings

Antropoceno XXI – A Fronteira da Acidificação dos Oceanos

23/11/2015 Pedro Pereira Leite Deixe o seu comentário

We’ll be talking about ocean acidification. What I’d like to do is touch on three things, first the chemistry of ocean acidification, the consequences of ocean acidification, and some of the connections, not just in the planetary boundaries framework but outside that as well.

So let’s start off with chemistry. The first slide here shows the carbon dioxide budget globally, and it comes from the Global Carbon Project based in Australia.

And towards the left you can see the amount of carbon dioxide emitted by human activities like fossil fuel burning or cement production. That’s the arrow, the big arrow, going upwards. There’s another upward going arrow and that comes from the carbon dioxide emitted from land use change.

Of all of the carbon dioxide we emit to the atmosphere about half of it stays there, and that’s why carbon dioxide concentrations are increasing. But what happens to the other half? Well, about 25% or so goes into terrestrial ecosystems, that’s the downward going arrow to the trees, and the other 25% ends up going into the oceans.

So what happens when you dissolve carbon dioxide in the oceans? Well the carbon dioxide forms a compound with water called carbonic acid, which then dissociates – that means it splits up and forms two ions – a proton H+ and a bicarbonate ion HCO3-. That can dissociate again, giving off another proton and a carbonate ion. And each time a proton is added to water it becomes a little bit more acidic. So, is that a global issue? Well, yes it is.

This particular image shows three different plots of ocean pH as a function of time.

The one on the far left is a pre-industrial case. And the color coding is proportional to the ocean pH, so you can see that the red colors are about 8.2, green colors are 8, the purplish-blue colors are 7.8-7.9.

And you can see in the pre-industrial case most of the oceans were 8 or above in terms of pH. Present day it’s still around 8, but there are fewer areas which are above that. Predicted for the end of the century you can’t see any places at all with pH of 8.

Now that doesn’t sound like much, right? But keep in mind that a tenth, the 0.1 pH unit, is about a 26% increase in acidity of the oceans. So we’re talking about a lot. What are some of the consequences, uh, of ocean acidification?

Well this plot shows a lot of different kinds of marine organisms, and it’s not so important, you can take a pause and look at more detail, but what you want to – to concentrate on first is increasing ocean acidity is going to the left in these plots, and calcification rate, that’s how rapidly organ– organisms in the ocean turn carbonate into a – into a shell is on the vertical axis going up.

And most of these plots either have a little bit of a – an inverse U-shape or it’s just going down, which means that most organisms in the oceans don’t like it when it becomes more acidic, they slow down the rate at which they make a hard shell out of the carbonate in the oceans. What does that mean really?

Well if you’re a coral reef you’re under stress from ocean acidification and other things like ocean warming and different kinds of pollutants. And you can go from the kind of beautiful, vibrant, very bio-diverse reef you see on the right to the kind of bleached reef you see on the left as a result of those changes in the ocean, including ocean acidification.

What are the implications and how rapidly can this happen? Well the graph on the top shows predicted increases, in carbon dioxide concentration for the atmosphere under a number of different scenarios into the future.

The bottom shows the aragonite saturation, that’s the point at which the equilibrium shifts from making aragonite, a kind of calcium carbonate, a soluble or an insoluble compound in the ocean, and that you can see will happen by the early mid-century for the southern ocean under most all of these scenarios into the future. So the point at which aragonite becomes soluble, or coral reefs might have a very, very difficult time, uh, existing at all, will be about mid-century or so, not too long from now.

Now that’s not the only stressor that marine organisms are facing. It’s one of the more important ones, but if you look at some of the other ones, like ocean warming, and other kinds of pollution you can see that the oceans are facing multiple stressors.

And in particular, on this plot, if you looked at the hatched areas, much of the southern ocean and much of the north Pacific and Atlantic oceans, will be faced by a number of stressors including, uh, ocean acidification. And all of the organisms that live there will be in a much more stressed environment.

You can get more detail about this, and other issues as well, in a book, Managing Ocean Environments in a Changing Climate. It tries to put all of these different stressors together and tells you how they fit with each other.

Which moves us into the connections part of the presentation. So you’ve seen this picture before, or at least some version of the picture.

This is the image of planetary boundaries. It’s not by chance, that ocean acidification and climate boundaries are right next to each other, because the driver for both is the same, how much carbon dioxide we emit to the atmosphere.

So this next to the last slide shows some of the connections between planetary boundaries, ocean acidification and the couple of other things, like food production. So you can see on the top we can produce food from terrestrial sources or on the bottom we can produce food from marine sources.

And the things that connect them are our planetary boundaries. So you see chemical pollution, for instance, from production of food on land might negatively influence coastal areas where we farm or fish, uh, for food. And nitrogen and phosphorus cycling, and what we’ve been talking about so far in terms of ocean acidification, the amount of carbon dioxide that we emit into the atmosphere.

And the important thing with this slide is to realize that all of these processes are fundamentally connected with each other.

You can’t really pull one apart and look it all by itself. Having said that though we’ll like to do a little bit of a reminder of what the ocean acidification boundary actually is.

It’s written in terms of aragonite saturation, that is, it’s a chemical equilibrium, and this might be a poster child for planetary boundaries in the fact that that’s a very, very easy boundary to define, because it is a chemical equilibrium.

If you add a little bit more carbon dioxide to the oceans aragonite becomes saturated, or unsaturated, so this is probably the easiest to define of all the planetary boundaries, and you can see on this slide exactly what it is.

Lectures / Readings

Antropoceno XX – a Fronteira das Alterações Climáticas

22/11/2015 Pedro Pereira Leite Deixe o seu comentário

In this lecture we provide scientific evidence why climate change is a planetary boundary, and the basis for defining the boundary for climate change.

It originates, not surprisingly, from the fantastic scientific explorations of our recent paleoclimatic conditions on Earth, again the stable climatic state we’ve had in the Holocene, shown here over the past 2000 years of reconstruction of temperature which varies at a maximum of +/- 1 degree or 2 degrees Celsius.

And as you see at the end the extraordinarily rapid pace of temperature rise in the world over just the past 150 years, since the Industrial Revolution, and our initial large scale emission of greenhouse gases from our industrial development.

This is the basis for the fundamental evidence that builds up the arguments around climate change. It becomes even more dramatic if you connect the past with the future, which is shown in the next graph showing the IPCC projections up until the end of this century.

And it’s absolutely extraordinary to see the Holocene stability which is again this churning up and down with a +/- 1 degree Celsius, and the fact that we are today heading on average along a pathway that will take us to in the order of 4 degrees Celsius warming during this century. And I think it’s absolutely clear just from this graph that we are at risk of pushing ourselves very rapidly outside of the Holocene stability.

Now up until today we have already increased global average temperature levels within the order of 0.8-0.9 degrees Celsius over the past 100 years.

What you see here is the distribution of that heat across the planet based on modeling and observations, and what you see is that in fact many regions in the northern hemisphere have actually even more warming already today, which is for example affecting one of the regulating systems, namely the polar regions in terms of its feedbacks in the stability of the Earth system.

The next insight building up the evidence for a climate boundary is that sea level rise is occurring at the pace of the projections we have or even faster. In fact much of the evidence today points at the risk of us underestimating the pace of sea level rise, particularly because we’ve underestimated the rate of melting which potentially could be irreversible in parts of Antarctica.

We’re also seeing unfortunately increasing robust analysis looking into the future that we’re following what I would actually call a disastrous pathway that leads us on average to three, four, potentially even higher, warming in this century. And that is coming out of the Intergovernmental Panel on Climate Change (IPCC) last, the most recent 5th assessment.

And here you see the synthesis graph showing the different scenarios to the future. The red line is the pathway that takes the world towards a totally undesired not Holocene-like state of 4 degrees C warming, and we know unfortunately that we’re following this path. So this is again increasingly showing that we need to do something very rapidly in putting a boundary on climate change to avoid moving outside of a desired state.

The next piece of analysis is related to the risk of tipping points and risk. And here science is advancing in a very profound way. We’re understanding the climate system much, much more in detail, and particularly how the climate system interacts with the other planetary boundary processes such as land, water, oceans, and biodiversity.

And this graph may seem a little bit complex, but it’s a really important insight that is coming out of the three last IPCC assessments. So what you see here is a risk assessment shown in red ambers, which has become a seminal and very famous set of graphs, of the risk analysis of the 3rd assessment to the left, the 4th assessment in the middle, and the most recent 5th assessment to the right. And what I want you to look particularly to is the column furthest to the right in each assessment which has a small darkened little block attached to it, which is the assessed risk from science of large scale discontinuities.

To put it in simple language, the risk of human-induced catastrophic tipping points. So this is the risk of us destabilizing the entire monsoon system, or irreversibly melting the Greenland ice sheet. And if you look carefully in the third assessment the risk of such large-scale discontinuities was assessed to occur at a point where the warming reached in the order of 4 degrees C. So on the Y-axis you have average temperature at which we risk these kind of catastrophic tipping points. But as knowledge advances, as our understanding of [how] the complex Earth has evolved, just a few years later in 2007 with the fourth assessment, as you’d see if you look carefully the threshold at which catastrophic tipping points can occur is down in the range of 2-3 degrees C.

And now in the most recent 2013 fifth assessment you see that the assessment from science is that these kind of large-scale discontinuities could actually occur even lower – in the order of 2 degrees C warming. And the reason why this is occurring is that we’re understanding more and more about resilience, about the risks that we have surprise and thresholds in the Earth system. And this to me is the most fundamental piece of evidence showing that a planetary boundary approach on climate is absolutely necessary because for one, at already very low temperature rises we today have evidence enough to say that the likelihood of large scale catastrophic changes is highly probable. And secondly, it’s highly uncertain. It’s so complex that we need to apply a precautionary principle where a boundary position is a position of safety beyond which we enter this area of uncertainty. And just to really hammer that point home, when you translate the latest assessment of the IPCC, our 5th assessment in terms of risk, something absolutely astonishing falls out.

We are today, in 2014, at a concentration of greenhouse gases for all gases, so carbon dioxide plus the other gases including methane, nitrous oxide, chlorofluorocarbons, and the short-lived climate forcers, including soot and sulfates and organic carbon, we are at 450 ppm.

Now we have taken the data in the IPCC and just translated them in probability of reaching different degrees at 450 ppm, and that is shown in this graph.

So on the X-axis you have temperatures and on the Y-axis you have the probability of reaching that degree of temperature at 450 ppm, at our current concentration of greenhouse gases. And look at the point which I’ve put on this graph which is 6 degrees C. I’ve taken an extreme warming, 6 degrees C is something totally outside of anything we can imagine, it’s an uninhabitable planet, it’s a degree of warming which any person, even a climate skeptic, would agree is totally unacceptable for humanity.

What’s the probability at 450 ppm according to the latest IPCC that we reach 6 degrees C Well on the Y-axis you see that the probability is a staggering 1.6%. Now what does a percentage, a probability of 1.6% mean? Well to give you and equivalent it would be the same as accepting that we have 1,500 aircrafts crashing every day. So it’s a probability level for catastrophic events, which in in any other sector of society would never, ever accept.

In fact, some of the large reinsurance companies after the IPCC released its report, clearly pointed out that we’re reaching a point of risk which goes beyond the point where they potentially can no longer issue, insurances because they can not be liable for the large scale costs that would be incurred if these kind of catastrophic events would be allowed to happen. So we’re entering truly a danger zone with regards to climate.

This is shown clearly in the next slide here on our analysis of how much forcing we are loading on the climate system. So what you see here is the last half million years how we are able to reconstruct in a very, very adequate way how much greenhouse gases we have in the atmosphere, how much forcing that includes. Forcing is the amount of watts, the energy that is trapped per square meter because of the greenhouse gases in the atmosphere. And look at the future.

What you see here is how we are rapidly moving out of the Holocene, moving out into a forcing and temperature rise which is way, way outside of the Holocene equilibrium. Now when we all take all this science together and synthesize it to define the boundary, we then apply our theory of a safe operating space, an uncertainty zone, and a danger zone, and we find that the science indicates that at the range of between 350 ppm and 450 ppm the science is well in agreement that here we have a risk of crossing catastrophic thresholds. And therefore we apply the boundary at the safe lower end of that uncertainty which is 350 ppm for carbon dioxide. And there you have it, that’s the way we place the boundary for climate change.

Lectures / Readings

Antropoceno XIX – A quantificação das Fronteiras do Planeta

21/11/2015 Pedro Pereira Leite Deixe o seu comentário

Now that we’ve identified the nine planetary boundary processes, the large scale processes of climate change, stratospheric ozone depletion, ocean acidification, the slow variables of rate of biodiversity loss, interference with the nitrogen and phosphorous cycle, land use change, freshwater use, and the two heavily human-induced risks around chemical pollution, aerosol loading, the challenge arises of defining quantitatively the boundary position for each one of these processes which distinguishes between a safe operating space and entering a danger zone where we have a higher probability of crossing tipping points which would take us away from a safe Holocene state.

Now in exploring that work, we look at the vast evidence in the latest science and try to identify first of all a control variable, an indicator or a parameter that regulates each process.

So for climate change, for example, it falls naturally to choose the concentration of greenhouse gases, and for each boundary we do the same.

And once we’ve identified a control variable, we try with the best of our knowledge to identify the point at which science indicates that we approach and are at risk of crossing a tipping point.

And that’s the way we pursue for each of the boundaries the exploration of positioning the quantifications of a safe operating space for humanity within the Holocene state. And the theory here is relatively simple but fundamentally important. And it’s shown in this graph of our – where we distinguish between the safe operating space in green, an uncertainty zone or a danger zone in yellow, and entering a zone of danger in red.

So what we’re doing for each boundary process is one, trying to identify a control variable which is a good indicator or proxy for the stability of a system.

So for example for the climate system we’ve identified climate forcing in – defined in the number of watts per square meter of increased heat in the atmosphere, and also carbon dioxide concentration as two good control variables for the climate system. And then we scan off all the scientific literature to try and – and explore what does science say today about the point beyond which, in terms in this case concentration of carbon dioxide, we may risk abrupt and irreversible tipping points which could push the Earth system outside of an Holocene-like state.

But the trick is that science of course is associated with large uncertainties, and will always continue to be associated with uncertainty, not necessarily only because we don’t understand the climate system in exact system but because all planetary boundaries interact to a point where it’s extremely complicated to put an exact point at which you cross a tipping point.

That causes and generates what we’ve called a zone of uncertainty, essentially a standard deviation in science. And that zone of uncertainty is the zone of uncertainty within science defined here as the yellow range. And somewhere in that yellow range we, with a very high probability, have the threshold, the point where the system crosses a tipping point.

Now here the planetary boundary theory takes its first and only normative stance. We have decided as a proposition in the planetary boundary framework to position the boundary at the lower end of the scientific uncertainty. This is applying a precautionary principle.

I mean you could, theoretically at least, place your boundary at the upper end of the uncertainty zone and – and rather have a more optimization-based approach. But we feel that it’s a very risky approach to take because we fear that somewhere in that yellow zone science indicates that we have thresholds that – with a very high likelihood will occur.

So the boundary position is at the lower end, and that gives us the green space below, so to say, when we stay below the control variable position we’re in a safe operating space. The upper end of the uncertainty zone then performs the threshold between the zone of uncertainty and a clear zone of high danger.

And that gives you the three positions in this graph, a safe operating space, an uncertainty zone, and a point beyond which we are a very high risk of crossing tipping points.

The reason why we have shown two graphs here is that for the systems where we have large scale tipping points we do try to explore exactly the point at which we had evidence of thresholds.

But for those processes such as land system change or fresh water use where there’s no evidence of planetary scale tipping points the change when we, for example, start overusing water or degrading land is that the system gradually becomes more and more degraded.

The response of the system is not associated, at least not as we know, with an abrupt threshold. What we try to identify then is the point at which evidence suggests that if we push the system even further, if we cut down even more forest, the feedback into for example the climate system is such that it could push the climate system across a tipping point. And that then becomes the point where we put the boundary.

So we have one set of boundaries defined on the point along a control variable beyond which the feedbacks can damage other systems, and for those systems which have thresholds we put the boundary at the point beyond which we actually can have a threshold.

So that is the fundamental thinking around planetary boundary theory, and I would very much encourage everyone to look at the literature around this which explains this very clearly.

Now what’s then the result? Well the result is in the following graph showing the nine planetary boundaries which when quantified, and in the original publication we made attempts of quantifying seven of the nine boundaries, we felt that we did not have evidence enough to quantify either the aerosol loading boundary nor the chemical pollutions or novel entities boundary.

But for this– the remaining seven we proposed quantitative boundary levels which they creates the safe operating space you see here on the graph.

And our original analysis showed that for three of these boundaries, which is indicated in the – in the red areas here which define our current state for each boundary, that we have transgressed and entered the danger zone for climate change, the rate of biodiversity loss, and the human interference with the global nitrogen and – for the global nitrogen cycle. In fact for phosphorus we estimate that we’re still within the safe operating space.

So this is to illustrate the way we can apply planetary boundary thinking, that if we can use science to define the boundary levels beyond which we can push the system outside of a stability domain we can actually monitor and keep track of where we are with regards to all the boundaries.

Now I really want to emphasize finally that because we are beyond a safe operating space for, for example, climate does not mean that have crossed the tipping point, it just means that we’re in a zone where we can potentially see tipping points occurring.

And unfortunately the observations we’re making, for example, both on biodiversity, climate and certainly on nitrogen, is in fact that we are inducing tipping points and potentially also have the start of irreversible change at the larger scale.

Now these estimates are all summarized scientifically in quite substantive scientific tables which are provided in the literature which is associated with the course we’re giving.

So I would very much encourage anyone to, say, following this lecture to also explore in more detail the contents and the quantifications as presented in the original table that we have in the 2009 publication, and I’d also like to flag that we’re right now currently, in August 2014, working on an update of a planetary boundary 2.0 which will provide the scientific update on the quantifications of the boundaries, a certain amount of refinement of the boundary definitions, and even attempts to quantify those unquantified boundaries which we had in the 2009 analysis.

Now in the final graph here you see the numbers that we had in the original publication. And you see here the – the boundary position, but also the uncertainty range which is then the uncertainty range in science.

And what you see here is, for example, estimates which for climate change is actually quite robust, or very robust, in terms of scientific evidence, that when we pass a concentration of carbon dioxide of 350 ppm – we are today at 398-99 – we enter a danger zone and we’re starting to see evidence of abrupt changes in both Greenland, inland glaciers, ocean acidification related to climate forcing, and changes in Antarctica.

Then we have a few boundary definitions which are more tentative. For example on nitrogen the definition we took at the original analysis was set at maximum amount of uptake of nitrogen from the atmosphere for fertilizer of thirty-five million tons of nitrogen per year.

That is roughly one-fifth of our current uptake from the atmosphere. Humans are the largest interference of the global nitrogen cycle, all categories. In fact our modern agriculture takes out more nitrogen in the atmosphere than the entire biosphere does naturally.

This number is based on a first best guess, and we’re working very actively to update this, but it shows at least that we’re able to take the first stab at identifying what are the safe boundary levels even for such complicated processes, which clearly are key for the resilience of the Earth system, in terms of defining quantitative safe levels.

And the science is – is advancing as we speak. In fact since the 2009 publication there’s a very, very broad set of fantastic, uh, groups of scientists who have critically assessed these first numbers and improved them, and in almost all instances come up with even better, um, proposals of quantifications, and that synthesis is – is something that we’re building on to continue [to] develop this framework, which increasingly has a very strong resonance out in both science, policy and business, and therefore also in its application in different sectors of society.

Actualités / News, Lectures / Readings

Antropoceno XVIII -As Fronteiras do Planeta

20/11/2015 Pedro Pereira Leite Deixe o seu comentário

Justification for the planetary boundary selection

What makes a planetary boundary process a planetary boundary process? Well, the key criteria that have to be fulfilled is that it’s an environmental process that is part of regulating the ability of the Earth system to remain in our current desired state, the Holocene equilibrium that has enabled human development of the past 10 000 years.

Together with scientists across the world we plunged into this challenge over several years of enquiry to try and identify what are all the environmental processes that qualify to this criterion of being absolutely fundamental in regulating the resilience and stability of our desired state of the planet? And the result is nine planetary boundary processes.

And I can tell you that this enquiry was extremely challenging, and we turned every stone of evidence to see what are the processes that could qualify to play this role? And we were actually ourselves surprised that there were only nine processes rather than 20 or 30 processes.

And this was put out, and it’s been put out for scrutiny for several years, and there’s so far not been any scientific suggestion of adding a tenth or eleventh process, or taking away one of the nine. So we’re today quite confident that if humanity can manage these nine processes within safe boundaries we have a very high likelihood of enabling a prosperous future for humanity on a stable planet.

Among these nine processes we have different types of planetary boundary processes, some of which have scientific evidence of planetary scale tipping points, some of them which do not have evidence of planetary scale tipping points, but which under the hood of the Earth system regulate the stability of those who have global scale tipping points, or that they have themselves sub-planetary scale tipping points at the ecosystem or biome scale, which if they cross tipping points at enough places in the world simultaneously could cause an impact at the planetary scale.

And this is why we define them as different categories of planetary scale and slow variables, which do not have evidence of global scale tipping points. And scientific evidence exploring the paleo record of how oceans have developed in the geological history of Earth indicates that oceans have large scale planetary level tipping points related to acidification, which makes oceans qualify as a planetary scale boundary process.

The planetary boundary process is an environmental process that is fundamental in regulating the ability of planet Earth to remain in the Holocene-like state. And the scientific enquiry here has then been exploring and deepening our understanding of what are the different processes that determine, for example, the ability for the climate to stay stable; for our polar regions to stay as they are today for the ability of our forests and oceans and land areas to continue to produce both food, air quality, and fresh water as it has been doing for the past 10 000 years. And in doing that and sharing that analysis with international leading scientists across the world the result is nine planetary boundary processes.

Now what is fundamentally important to recognize is that to be and to fulfill the criterion of a planetary boundary process does not require that that process is associated with a planetary scale tipping point. The key is what are the processes that regulate the ability of the entire planet to stay in the Holocene? But among the nine processes that we’ve identified, three of them have evidence of planetary scale tipping points, as shown in this graph.

That is the climate system. Clearly we know that in the past history of the Earth system the climate system has been pushing the entire planet in and out of glacial and interglacial periods, for example.

Ocean acidification is another such process where we see paleoscientific evidence that the entire ocean can go from anoxic to oxic events, so basically oxygen-free or oxygen-rich states, that the ocean can actually flip between different stable states.

And clearly the stratospheric ozone layer, which is the protective layer in the upper atmosphere, which protects the entire biosphere from harmful radiation from the Sun.

But then we have, perhaps more surprisingly, six processes that science now believes qualify as planetary boundaries but which don’t have planetary scale tipping points. And they fulfill the criterion for two reasons. One is that they play a fundamental role in regulating whether or not the large-scale processes potentially could cross a tipping point. So for example land use systems, fresh water use, and biodiversity, which are fundamental in providing the capacity of land areas to be carbon sinks, and if that ability is not there climate system would very rapidly cross a tipping point. And another example is the ability of land areas to sequester and keep nutrient flows intact as a way of regulating the amount of different pollutants in the air.

So among the processes which have this ability of operating under the hood of the Earth system and regulate its ability to stay in the Holocene we’ve identified four, which are biosphere processes forming part of planetary boundaries.

One is the interference, or the way we manage the large biogeochemical flows of nitrogen and phosphorus, which together with carbon are the big cycles in the world.

Atmospheric aerosol loading, which is the amount of soot and pollutants in the air, which in turn regulates the stability of the large rainfall systems, for example in tropical regions, such as the monsoon.

Global fresh water use, which is one a significant greenhouse gas, as water vapor, but also the fundamental role of water as the bloodstream of the entire biosphere, regulating the amount of biomass which in turn regulates the amount of carbon in the entire Earth system.

Land use change, which is the fundamental fabric for all living species on Earth.

And biodiversity, the genetic diversity from animals and vegetation and trees, forests, which overall determine the ability of the biosphere to cope with and adapt to changing conditions on Earth.

Now finally we also identify that there is most likely one final ninth planetary boundary, which we originally defined as chemical pollution, and increasingly talk of as new entities.

This is the recognition from increasing evidence, despite its complexity, that the cocktail of chemical accumulation in the biosphere could potentially cause major shifts in for example the genetic composition of species on Earth, which could be a tipping point in terms of life conditions on Earth.

So overall therefore nine planetary boundaries: three of which have evidence of large scale tipping points; climate, stratospheric ozone layer, and ocean acidification; four boundaries which operate a little bit more at the smaller scale but regulating the Earth system: biodiversity, land, water, nutrients, and fresh water; and two boundaries which are very heavily anthropogenically caused: both air pollution, which we call aerosol loading, and chemical pollution.

Now are there tipping points among these that operate below planetary scale? And the answer is yes, so that’s the second criterion why even those that do not have planetary scale tipping points qualify as planetary boundaries.

For example, biodiversity loss is increasingly shown to be involved in tipping points at ecosystem scale. And in the Anthropocene we see the risk that we can have tipping points occurring in so many places in the world that they aggregate into becoming a planetary concern.

So it’s not necessarily so that a system has to have one tipping point at the planetary scale, you can have multiple tipping points, and if they occur in enough places simultaneously they actually add up to a potential influence and impact factor at the Earth system as a whole. So there you have it in a nutshell where the planetary boundaries originate from.

Actualités / News, Lectures / Readings

Antropoceno XVII – A ferramenta Fronteiras do Planeta

19/11/2015 Pedro Pereira Leite Deixe o seu comentário

Introducing the planetary boundaries framework

The theory and the evidence behind the Anthropocene and social-ecological resilience, so you now have a very firm floor to explore the opportunities and the tools to navigate the Anthropocene. So this was the end of the first cluster and now in the fourth module we’ll be taking us into the new cluster on Planetary Boundaries.

The last module in this cluster on Planetary Boundaries will be introducing the three large processes, the three large planetary boundaries with global scale tipping points: climate change, ocean acidification, and ozone depletion.

To do this in the best way, we’ve invited Professor Kevin Noone from the Department of Applied Environmental Sciences at Stockholm University who also is a co-author of the Planetary Boundaries research who is joining us for this week.

In this lecture we’ll be exploring the origins of the planetary boundary framework. And it emerges from fantastic advancements in Earth system science over the past 30 years, and it’s the result of the collision of two pieces of scientific enquiry.

The first one is the insight that we’ve entered the Anthropocene; the exponential pressures on the Earth system that we now have become a geological force of change at the planetary scale, which collides with the insight that we can no longer exclude catastrophic, irreversible tipping points in the Earth system.

Now when you combine these two you have to conclude that we now need to consider the following very dramatic question. Could we as humanity push the entire Earth system outside of its current stability domain?

Which is illustrated in this graph showing that the planet can actually reside in multiple stable states separated by a threshold.

But to start that enquiry we must first ask ourselves: what is our desired state?

And science shows very clearly, as shown in this following graph, which shows ice core data over the past 100 000 years, that the Holocene, the past 10 000 years of extraordinarily stable interglacial conditions on Earth, is in no doubt humanity’s desired stable state which has enabled our modern civilizations to develop as we know them.

This is the period when we’ve had extraordinarily stable climate, varying with only 1 degree Celsius up and down over the entire period. This is a period where we know the global carbon cycle, the global nitrogen and phosphorus cycle, all the biogeochemical processes that regulate the stability, which has enabled Earth to stay in the Holocene.

So the starting point of thinking around a planetary boundary framework is the recognition that the stable desired state of the planet is the Holocene, and therefore our endeavor is to try and define what are the Earth system processes that regulate the Earth’s ability to remain in a Holocene equilibrium, in a Holocene desired state?

If we can identify those environmental processes, the next question is: can we for each one of those try and identify a control variable and put a quantitative science-based boundary beyond which we risk feedbacks, interactions, and surprise that could risk the entire system to move over a tipping point and push the system outside of the Holocene?

So that in a nutshell is what the planetary boundary framework is about. It’s recognizing that today we are potentially moving in this direction where put very, very eloquently and sharply by Ban Ki-moon, Secretary-General of the United Nations, “We have our foot on the accelerator driving towards a threshold or an abyss,” meaning that we see signs that we might actually be approaching tipping points in several of the Earth system processes that regulate the stability of the entire planet.

Now, I’d really like to emphasize that this work, which was published in 2009 in Nature with a large group of highly recognized Earth system scientists across the world, covering expertise from the climate system, the cryosphere, oceans, hydrology, ecology, this work was based upon empirical advancements in research over the past decades. So it’s really the next incremental stage of advancements in research such as the understanding that we can no longer exclude tipping elements and climate; understanding that we have ecological capacities which define the stability of many of our ecosystems, which means that the planetary boundary concept resides on three pillars of scientific enquiry.

The first one is clearly the Earth system understanding of the planet as a self-regulating geobiochemical system where the interactions occur all the time between the biosphere, the atmosphere, the cryosphere, the hydrosphere and the climate system, and that we are safely enveloped around the stratospheric ozone layer.

The second line of enquiry is the work residing or coming back all the way to the early 1960s around ecological footprints, Herman Daly’s work on steady state economy, Kenneth Boulding’s thinking around Spaceship Earth, ecological economics research, the research advancements understanding the relationship between human needs and the capacities of our biosphere to support humanity.

And the third line of enquiry is the enormous advancements we’ve made in understanding the nonlinear dynamics in complex ecosystems and biomes, the whole domain of resilience theory, complex systems research where we’re understanding increasingly that systems can actually cross tipping points and change very rapidly.

So planetary boundary theory and its framework originates from these three lines of enquiry and is a natural next step in our understanding. But it differs very significantly from many of the previous concepts that we’ve been exploring.

So you’re probably familiar with different concepts such as limits to growth, carrying capacity, guardrails for climate, or tipping elements in the climate system. But the most famous of these is the limits to growth.

And I really want to emphasize that even though they complement each other, they’re distinctly different, because limits to growth, which was developed by Dennis and Donnella Meadows and was part of the Club of Rome report that came in 1970s, in the early 1970s, was based on the following analysis.

It tried to estimate the resource base that we have in the Earth system, natural resources, everything from soil to metals to oil to finite fresh water resources, and then made assumptions regarding technology and tried to estimate human needs. And then it compared the resource base, basically what Earth could provide, the supply side, and humanity’s demand side. And when the demand side exceeded supply we were in overshoot.

And then the analysis made assumptions around how that overshoot could play out in future risks, for example, the climate system. But it had to make assumptions on technology and human demands. Same for carrying capacity analysis, which always are based on assumptions on technology and human needs.

Now history shows that these analyses tend to underestimate human ability to innovate, that we tend to be more clever in terms of, for example, ensuring the capacity to feed ourselves despite resource constraints.

The planetary boundary framework does this very differently. It backs off in terms of humanity and simply tries through scientific enquiry to interview planet Earth and see whether Mother Earth could answer the question, “If you were left alone, and if you would like to answer for us, what are the Earth system processes that determine your ability to stay in the Holocene, what are these processes?

And for each one of these processes how far can we push you beyond which you will move yourself outside of the Holocene?”

So the planetary boundary framework decouples itself from humanity in the diagnostic and the definition of the boundaries. This gives us a safe operating space, which is entirely biophysical. It makes no assumptions of human needs, no assumptions on human innovation capacity. And then you can put back humanity inside that safe operating space.

So it liberates ourselves from the risk of making underestimates, overestimates of our ability to develop. And therefore I believe that the planetary boundary framework is so useful in support of our endeavor of enabling and ensuring human prosperity in the Anthropocene, because it’s entirely a science-based enquiry of what it will take for the Earth system to remain resilient and stable in the desire Holocene-like condition.

And then we can take the enormous challenge of finding solutions, exploring technologies, addressing ethics, addressing a fair distribution of remaining ecological space, and addressing the very, very complex questions around democracy, ethics, transparency, governance, economic growth, etc. But that comes inside the safe operating space, it’s not being challenged and it’s not normative in terms of its definition of the boundaries.

Lectures / Readings

Antropoceno XVI – entender a complexidade num mundo turbulento

18/11/2015 Pedro Pereira Leite Deixe o seu comentário

Human development in the Anthropocene requires that we understand not only the rising human pressures on ecosystems, nature, and the planetary system as a whole, we must also understand how nature and the earth system responds.

We’re learning more and more from empirical research around the world, that nature doesn’t respond in just incremental and linear ways. In fact, we now recognize that systems from coral reefs, to rainforests, to temperate forests, have several distinctly different states, separated by thresholds.

So, a system can be either a rainforest or a savannah. And if a system is pushed through environmental changes, across this threshold, we talk of a tipping point. When a system changes fundamentally its structure and function, and tips over from one stable state to another stable state. So strictly speaking the definition of a tipping point is when a system fundamentally changes structure and function, and settles into a new stable state. And the prerequisite to do so is that a feedback mechanism, which keeps the system tightly in one state, changes direction.

For example, a rainforest, its feedback is that it sustains its own moisture – it’s a self-wettening system. The feedback is that the green canopy sucks out a tremendous amount of water from the soil, feeds that back a vapour back into the atmosphere, and self-generates rainfall, and also keeps moisture within its very tight, dense canopy. That’s the feedback keeping it in a rainforest state. When that system is cut open through deforestation, it dries out, and warms up due to climate change, the feedback can change into a self-drying system, where instead it being wettening, becomes a self-drying system, and the system crosses a threshold, it becomes a tipping point, and gets locked as a savannah.

This is “tipping points.” Now tipping points have been explored for decades, and have been understood in small ecosystems from lakes and forest systems, but increasingly we see evidence that large-scale systems can also be subject to tipping points.

And this is just one example of a potential tipping point that really, really concerns scientists across the world. It’s data from Greenland, showing on the x-axis months of the year, and on the y-axis showing the percentage of incoming heat from the sun, which is reflected back to space – what we call Albedo.

Now in the coloured thin lines, you see the stable state with a permanent ice layer on Greenland. When the ice is stable it is a very white colour, and as well all know, a white, light colour reflects back roughly 90-95% of incoming heat. And that’s exactly what we see. It goes down a little bit during the Arctic summer of June-July, when the fringes of Greenland always melt and become a slightly darker liquid surface, but overall, it’s a mirror, it’s a cooling system, it’s a prerequisite for the earth to stay stable in the Holocene.

But look at that thick red line, which are observations from NASA in 2012. An extraordinary exception suddenly, for two weeks in July, the feedback changes direction from being a mirror, reflecting back heat, ie. a cooler, to becoming a net heat absorber. More than 50% of incoming heat is sucked up because for the first time in observational history the entire Greenland ice sheet is melting and covered by a liquid darker surface. Now Jason Box at the Byrd Polar Research Institute concludes in calculation that just these two weeks of change in feedback corresponds to a new injection of heat of in the order of 300 exajoules of energy.

Now 300 exajoules is a very difficult number, but just to give you some comparisons, the annual energy consumption in the US is in the order of 200 exajoules. The annual global energy consumption is a bit more than 600 (exajoules). So momentarily this means that Denmark bypasses China and the US as the world’s largest climate forcing nation. And this occurs when Mother Earth changes directions in the feedback, which potentially could be a tipping point.

Now for the Arctic, for example, there is emerging research showing that several systems can be subject to these kind of tipping points. Such as a flip in the Arctic Sea ice cover, meaning that it could suddenly flip over into a situation with permanent open sea.

And other systems that keep the ocean circulation functioning between the Arctic Sea, and for example, the Atlantic. Now recent research on Greenland shows something quite remarkable. Ice core data, looking at the conditions on earth the last time we had a warm interglacial, the Eemian warm interglacial period, some 120 000 years back. To explore whether or not the Greenland ice sheet melted in its entirety.

The reason why this question is so critical is that at the time, during several of thousands of years, mean average temperatures were more than 4°C warmer than today. And normally, we have always expected that if we would reach a 4°C warming, an exceptional situation which we haven’t seen for 4, 5, 6 million years in a longer time period, that the entire Greenland ice sheet would melt.

But this recent data, led by Dorthe Dahl-Jensen, one of the world’s leading glaciologist, shows something surprising. Maybe that Greenland, in fact, did not melt. In fact, only contributed to in the order of 2 metres sea level rise, in a world that we know, with high degree of certainty, had a sea level which was 6-8 metres higher.

How come we know that the sea level was 6-8 metres higher? Well, we see that from very, very good data on coastal regions that show remnants of fossils from this period. So, we’re quite certain about the sea level rise. This shows, and gives us something of quite remarkable good news. It indicates, in fact, that Greenland is most likely more resilient than we previously thought.

Resilient in the sense that even a +4°C degree warming would still keep the Greenland ice sheet, you know, relatively in tact. But the drama is the following: if that’s correct, and Greenland thereby only contributes to 2 metres sea level rise, where is the lacking difference?

Because we’re missing in the order of 4-6 metres sea level rise, which must have caused, or been triggered, from somewhere else. And the trick is that there is only one potential candidate as a source for that rise, and that is Antarctica.

Antarctica, which we’ve always thought to be a more resilient system than the Arctic. And remarkably, just this year, 2014, two separate research teams have recently published data of, I would call it even shocking nature, showing from observational evidence that several glaciers in the west Antarctic ice sheet potentially have crossed the tipping point, and now have entered irreversible melting, which could explain this rising vulnerability. If this is correct, it would actually mean that we have to revise our average estimates of sea level rise for this century, from roughly 1 metre to 2 metres, so a doubling in risk for this century.

So this is showing why it’s incredibly important for us now to understand the risk of tipping points in large systems that regulate the stability of the earth system. But it goes not only for the polar regions, similarly, science shows the same kind of risk pattern with regard to the large rainforest systems.

This is data from the Amazon rainforest, showing the unprecedented droughts from 2005 and 2010, which led to a remarkable penetration of drying, even inside the rainforest. And increasing evidence indicates that these kind of shock events, of droughts related to global climate change, together with the large and vast deforestation, which open ups tracts of forest leading to more dry air penetrating the normally moist canopy, could in fact lead to abrupt behaviour, meaning that the system could tip over and, quite abruptly, shift into a savannah. Mapping out these risks globally is increasingly a key priority for science.

What you see here is one such effort of trying to identify the hotspot systems in the world where we could anticipate this kind of shift occurring from one stable state to another stable state if we cross a threshold, leading to a tipping point.

And what you see here is that this goes not only for the polar regions and the Amazon rainforest, but for example, for the large rainfall systems, in both the southeast Asian monsoon, the west African monsoon, which sustains livelihoods for hundreds of millions of people.

The risk that we get abrupt shifts in methane release in permafrost; a shift from a frozen to a thawing, and permanently thawed system. And these risks of tipping points, now at the large scale, is a fundamental importance in understanding what occurs in the earth system. But finally, this also has direct operational implications for the way we manage large sectors in society.

This is an attempt to analyze, for example, is there a risk of inducing tipping points also when it comes to freshwater systems? Not due only to climate change, but the combination of climate change and land management. And what you see here is a first analysis of hotspot regions in the world where you could see a fundamental shift in freshwater supply, if continued unsustainable management is pursued.

Where we see shifts in moisture feedback related to deforestation, which changes rainfall patterns, which could abruptly shift runoff flows and rivers, and thereby undermine the possibility for irrigation, and freshwater supplies to cities. So, the large scale regulating systems in the polar regions, for example, connect to the direct operational scales of managing food security in the world, across different scales.

So overall the conclusion is that in order to navigate sustainable development in the Anthropocene, we need to understand both pressures and tipping points, and together this allows us to explore: what is a safe operating space for development?

Lectures / Readings

Antropoceno XV – Resiliencia do Planeta e interações multi escalares

17/11/2015 Pedro Pereira Leite Deixe o seu comentário

When we’re exploring sustainable development in the Anthropocene in the era when we no longer can exclude undermining the way the entire Earth system operates, we must understand and explore what resilience means across different scales.

So we’ve been exploring the resilience of systems, the ability of a household or an economy or a rainforest to withstand different disturbances without shifting into a different structure or function, for example, a rainforest tipping over into a savannah. We must explore what is the risk of pushing the entire Earth system outside of its stable state. We call this Earth resilience.

Earth resilience is entirely dependent on the different components of the Earth system operating together and either through what we call negative feedbacks, meaning processes that dampen change, or through positive feedbacks, where processes actually accelerate change, and applying these interactions regulate the ability of the Earth system to remain either in a Holocene-like state or propel itself outside of that state.

So in exploring Earth resilience we must also understand what we call cross-scale interactions, how for example a carbon sink or a methane sink in a local forest, or a wetland, or a savannah, interacts with the atmosphere or the polar regions, so from a local, to a regional, to a global scale. That is different to Teleconnections, which is when one system changes in one place of the world and has domino effects on other systems.

For example when a forest system that feeds back moisture and creates rainfall affects the monsoon system several continents further away. These are complex notions but must be understood in the Anthropocene. And in this lecture we’ll explore a bit further what we need to understand when we define Earth resilience. Now it takes us back to the absolute starting point when defining our desired future, which is going back to the ice core data which defines our desired state, namely the Holocene. So this is again the hundred thousand years of change in the world showing that the last ten thousand years in the red circle here is an unprecedented stable state of the planet. In fact we can call this the Eden’s Garden of human development, the stable state within which we want to remain.

The reason why referring to this state when exploring Earth resilience is that the Holocene is a state that we understand very well. We know the carbon cycle, the nitrogen cycle, the phosphorus cycle, and the limits within which essentially all the key parameters that regulate the stability of the Earth system have been operating over the past 10 000 years, illustrated for example in this extraordinary set of data showing concentrations of carbon dioxide and methane over the past 400 000 years.

And if you look very carefully you’ll see the very stable and narrow range within which these gases operate over the past Holocene, and the blue arrow showing how we are moving away from this very stable state.

This Is very helpful, it actually helps us define a safe operating space for human development because we understand fairly well how, and what are the conditions, within which the Earth system can operate in the Holocene. Now the excitement about this comes across I think in a very pedagogic way in the following exploration of what role does the biosphere, the ecosystems of the world, play in terms of trying or attempting to maintain a Holocene-like state? And let me just run through this example to you in quite detail.

So we are emitting greenhouse gases and have been doing so since the Industrial Revolution in the end of the 18th century. We’ve emitted an estimated 365 billion tons of carbon from industrial emissions, and another 180 billion tons of carbon from land use change.

That together ends up in an enormous 545 billion tons of carbon emitted cumulatively since the Industrial Revolution. This is relevant because carbon remains in the atmosphere for over 1000 years. So what we did 200 years back is still warming the planet.

The big question is temperature has risen with almost 1° Celsius since the Industrial Revolution. Is it all of these 545 billion tons of carbon that now reside in the atmosphere causing 1° Celsius warming? The answer is no, because the astonishing reality is that over half, roughly 55%, of these emissions are actually absorbed by the living biosphere, 155 billion tons in the oceans, and another 150 billion tons are estimated to have been taken up by terrestrial ecosystems.

This is the most profound proof that the Earth system, through its biogeophysical processes, is applying Earth resilience in practice, meaning that the Earth system is applying these processes to try to remain in its current stable state, the Holocene, by dampening the impacts of our disturbance, emitting of carbon dioxide in this case.

And these carbon sinks are tremendous. And the net remaining amount of carbon in the atmosphere is only 240 gigatons of carbon which has contributed to the temperature rise so far.

Same story goes for heat, for example. 95% of the heat caused by global warming is stored deep in the oceans. These are all processes that try to dampen and maintain the self-regulating biogeophysical processes in the Earth system in the Holocene-type state. Now it goes beyond just understanding the big climate system.

There are critical functions that all the biomes play in regulating Earth resilience. So the polar regions, for example, are permanent white surface areas that reflect roughly 90% of incoming heat from the Sun, reflecting it back to space. These polar regions are massive air conditioning, cooling systems for planet Earth, thanks to their permanent white surface.

These are negative feedbacks. They’re actually cooling the planet. When ice melts and changes color to a liquid surface, just that color change means that instead of reflecting back heat and functioning as a cooler polar regions can transform themselves into becoming net absorbers of heat, meaning becoming positive feedback triggers, self-generating heat.

Same with rainforests currently being huge carbon sinks, regulating moisture feedback and rainfall patterns across the world, being residuals or residing massive hosts for biodiversity, and also generating oxygen; marine systems functioning and heat conveyers, carbon sinks, and banks of genetic diversity; the world’s temperate organic systems being sinks and huge stores of methane; the temperate forests also being major carbon sinks and regulating rainfall patterns and generating oxygen across the world; and finally savannah systems that are playing also a role as moisture feedback, and regulating carbon and rainfall patterns; altogether systems that define Earth resilience.

And the key insight here is the recognition that in the past we’ve been very preoccupied of managing ecosystems at the local scale. This has been important for local livelihoods and local opportunities for good living conditions. Now we must connect the local to the biome scale, and the biome to the planetary scale, and recognize that we have to become stewards of all these systems collectively because they determine the ability for any scale, from household to business to nation, to develop in the future.

Global Heritages

Arquivo mensal: Novembro 2015

Antropoceno XXIX – Sintese sobre Fronteiras do Planeta

Antropoceno XXVIII – As novas fronteiras

Antropoceno XXVII – A fronteira dos aerosóis

Antropoceno XXVI – A fronteira do ciclo do Fósforo e do Nitrógeneo

Antropoceno XXV – A Fronteira do Terra e da Água

Antropoceno XXIV – A Fronteira da Perda da Biodiversidade

Antropoceno XXIII – As 4 fronteiras silenciosas

Antropoceno XXII – A Fronteira do Ozono

Antropoceno XXI – A Fronteira da Acidificação dos Oceanos

Antropoceno XX – a Fronteira das Alterações Climáticas

Antropoceno XIX – A quantificação das Fronteiras do Planeta

Antropoceno XVIII -As Fronteiras do Planeta

Antropoceno XVII – A ferramenta Fronteiras do Planeta

Antropoceno XVI – entender a complexidade num mundo turbulento

Antropoceno XV – Resiliencia do Planeta e interações multi escalares

The inclusion of community knowdlege on territorial development