Arquivo de etiquetas: Mudanças Climáticas

Environment and Health I

Climate Change and Health

When we talk of global health in the 21st Century, one of the most important things that comes up is climate change and what its impact on global health is going to be and how can we actually respond to this major challenge, which is not merely environmental or ecological, but also threatens global health in very many ways. When we look at the temperature changes that have happened over a long period of human existence, over the last 20,000 years there have been some fluctuations in temperature, mostly because of changes in the way the earth has a planet has changed its ecology. However over the last 10,000 years we have had fairly stable temperature patterns which have helped humanity to thrive and progress. But towards the end of the 20th Century we have seen human interventions change the nature of the environment to the detriment of the climate, by raising temperatures high and at a very rapid pace so that the planet really is not prepared for this level of change. And this inevitably has an impact on health and nutrition. There is unequivocal evidence on climate change. We recognize that there are rising sea levels and global temperatures, retreating glaciers, extreme weather events. And despite some climate change deniers, there is absolute global consensus that climate change needs to be recognized as an important threat to humanity and that we need to collectively do something about it. Since the Industrial Revolution, atmospheric carbon dioxide has increased by a third. And the International Panel on Climate Change projects an increase in global temperatures by at least 1.8 degrees centigrade by 2100, by the end of this century, as the best case scenario. But there are other scenarios, if we do really nothing, of a doomsday scenario where the temperature can actually rise to up by about 5.8 degrees centigrade. And an increase in sea levels between 9 and 88 centimeters is very much possible in the next century, depending upon how much the temperature rises. Most of this change is related to human activity. That means it is anthropogenic. It is not mediated by natural changes in the earth’s environment or its geology, but it’s contributed entirely by humans. We recognize that there are very many scenarios possible with a wide range of temperature changes that are likely to occur based upon the International Panel on Climate Change modeling. But we do recognize that even in the best guess scenario we are likely to have a two-degree temperature rise or more if we do not do anything. Apart from the natural variability that occurs in the earth’s own environment, anthropogenic climate change will contribute substantially. And the kind of hazards that occur because of a variety of environmental distortions can actually accentuate global health challenges depending upon the amount of exposure that different population groups have, how vulnerable they are to these effects, and the impacts will automatically vary according to that. But there are also appropriate responses in terms of socioeconomic actions that we can undertake for mitigation as well as adaptation and how we can actually insure that there is a concerted global response to reduce some of the mediators of climate change. And they all will impact upon global health ultimately. In terms of human exposures there can be fairly acute events like heat waves or extreme weather events, also more steady rises in temperature as well as alterations in precipitation which can play out their effects over the longer period of time. Quite often the skeptics say, where is climate change because of global warming when we see sometimes extreme cold weather? That’s because global warming itself can disrupt weather patterns substantially resulting in what we can call freaky weather. Beyond global warming we are actually seeing global harming in very many ways. Based upon what the contamination pathways are, what the transmission dynamics are, and what’s the nature of changes in agro-economic systems and ecological systems and hydrology as well as the degree of socioeconomic and demographic disruption that takes place as a result of some of these exposures, you can have a variety of health effects. These will be temperature related illness and death, extreme weather related health effects, air pollution related health effects, water and food borne diseases, vector borne and rodent borne diseases. Effects of food and water shortages, particularly when agriculture and water supply are substantially affected. Mental, nutritional, infectious, and other health effects. Cumulatively, climate change can play havoc with human health over a period of time. There are direct effects of climate change, mainly from extreme weather events. Like for example, temperature extremes. In 2003, we had the major European heat wave. And most deaths were in the vulnerable populations, especially elderly with preexisting diseases. France particularly experienced this. And over 70,000 people were estimated to have died in the hottest summer that the world experienced since 1540. But there are also indirect effects of climate change which act via changing patterns of disease. Vector borne diseases, for example those due to mosquitoes or rodents. As the weather warms up, mosquitoes will start breeding at higher latitudes and at higher altitudes. And therefore you’ll see the spread of malaria to places which did not experience it before. Water, sanitation and hygiene related diseases are also going to be a major public health challenge. Reduced crop yields at lower latitudes will result in food shortages, accentuating food insecurity. At the same time, there will be migration compelled by climate change and related extreme weather events. So you’ll have climate refugees and population change will occur also as a result of that. We also recognize from the IPCC’s report that there will be negative impacts on crop yields. But while the whole world is going to be threatened, there will be some vulnerable populations within countries who are likely to suffer particularly more severe effects of climate change. The very old and the very young and the very poor and those who are socially and culturally marginalized are likely to suffer most, particularly you can imagine the plight of the homeless who have to live in very hot climates in the outdoor, exposed to extreme heat. Vulnerable cities. There are about 16 of the 23 global mega cities which are located in coastal areas. And they will have greater exposure to extreme weather events and storm surges. We’ll also see that climate change will accentuate conflict. It has been recorded that deviations from temperature and precipitation patterns correspond to significantly marked rise in conflict. And these are statistically significant rises. One degree increase in temperature, a rise in temperature increase the frequency of interpersonal conflict by 2.4% and inter-group conflict by 11.3%. So when we talk of hot weather, we must also recognize that people become hot tempered as a result. And the effect of rainfall on inter-group conflict is also interesting. As climate change reduces the amount of rainfall and accentuates water shortages, it has been noted that there is likely to be a greater possibility of inter-group conflict where they’re vying for scarce water resources. There is also a big challenge of how to adapt and how to mitigate. Mitigation is reducing the possibility of global warming through effective action. Adaptation is trying to adjust to some of the effects of climate change as it occurs and trying to improve our opportunities for survival despite some of the changes that we could not prevent. So the IPCC again suggests that the adaptive capacity is intimately linked to economic and social development. But this is unevenly distributed across countries and within countries, across population groups. Adaptation plans must be place and context specific. Like for example, heat action plans for different cities or looking at disaster response for different coastal cities. Action is needed at all levels, from individuals to governments. And the first step towards adaptation is reducing vulnerability and exposure. In terms of climate change, the mitigation strategies of course are very important to reduce the projected rise of temperature, even to limit the temperature rise to 2% or less is going to be a major challenge. And for this, we need to act in the main domains that are contributing to climate change. Food and agriculture. Our food and agriculture systems are now causing environmental disruption. And they themselves will again in turn suffer because of the effects of climate change. So this mutual degradation is something that we must stop because our food and agricultural systems are becoming water intensive, they’re also resulting in a lot of deforestation and all of this is something that we must take into account when we plan mitigation strategies. The use of household fuels, the increasing use of vehicular transport, and the way we generate power through coal plants, all of these are going to be important elements that we must look at as we design strategies to reduce the kind of forces that accelerate climate change and thereby we plan effective mitigation. When we look at some of the health co-benefits of climate change mitigation, we must recognize that the determinants are fairly common and the benefits are likely to be also complimentary. For example, when we talk about public transport and we promote cycling in cities, or more safe pedestrian pathways and reduce the dependence on vehicular transport, obviously in addition to reduced carbon emissions there is improved physical activity. There is also reduced air pollution with benefits for prevention of respiratory illnesses. And the improved physical activity itself will reduce the risk of diabetes, heart disease and other non-communicable diseases, including some cancers. Similarly, reduced meat consumption is something that we must look at, because livestock breeding is now responsible for 50% of global methane emissions, so it’s important that we address that even from the point of view of the environment. The WHO has come up with a work plan. It suggests that we must act, actively engag in advocacy to try and mitigate climate change but also promote appropriate plans for adaptation across the world, especially country level plans. It also suggests that we must promote partnerships to insure that health is well-represented in the climate change agenda. Climate change is not merely a matter for meteorologists or environmental experts or energy experts. After all, the consequences are going to be felt in terms of human health and nutrition. So the health community has to be there at the table when climate change agenda is being discussed. The WHO also says that we must coordinate reviews of links between climate change and health to develop a very strong research agenda which can inform and influence these debates on climate change from the health perspective. It also calls for strengthening of the health systems in countries and would like to assist countries in addressing their health system deficiencies and build capacity to reduce health vulnerability to climate change, the whole plan for adaptation. There are also main research areas in the climate change and health area. Firstly we need to establish baseline relationships between climate change and health. We must gather evidence for early effects of climate change. We must develop predictive modeling techniques and try and anticipate what are the likely consequences of positive or negative changes in the weather and the environment. And in terms of looking at the adaptive options and evaluating their comparative cost effectiveness in different country contexts, we must also estimate the benefits and costs of mitigation and adaptation overall. It is not far-fetched to think that if we do not control the forces that are accelerating climate change, human health would not only be degraded over the century that we live in, but in future centuries it may actually result in elimination of humanity itself. So it is from the public health perspective, from a global health platform that we must now engage in the debates on climate change and demand that climate change must not occur to the extent that humanity’s life would be threatened and also plan for mitigation and adaptation in the most effective manner possible in every country on earth.

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Growth within Planetary Boundaries I

The Planetary Boundaries 

We’ve been talking about economic growth, how it started, how it diffuses, what the big problems are, how countries still trapped in poverty can spring free of the poverty trap. But the problem, we know, is more complicated than that. What if the world achieves economic growth? What if the poor countries, as they hope and rightly deserve, catch up with the high income countries? What then for the planetary boundaries? What then for an environment already under tremendous stress? Remember that sustainable development makes a key point, that economic, social and environmental systems are interlinked.

So, I want to focus now more deeply on how we might even conceive of bridging this terrible problem of global economic growth, the good that we want, the progress for poor countries, with a worsening environmental crisis. We have to understand the environmental systems and how humanity is effecting them. Then we have to look for practical approaches. How we can reduce the pressures that humanity is placing on the climate, on the oceans, on the land, or other species. So that we can reconcile these two objectives and indeed, make it possible to achieve all three of the basic goals of sustainable development. Economic growth, fairness and social inclusion and environmental sustainability.

Remember the concept of planetary boundaries or the fact that we’re living in as new geologic era, the anthropocene. Both these concepts, planetary boundaries and anthropocene, signify that humanity has become so numerous, our 7.2 billion people and rising, and so effective one could say, so productive in the capacity to mine and extract resources. To transform resources for production in industry, to consume, that we have suddenly, unprecedentedly as a species, hit these planetary risks and even dead ends if we’re not careful. The concept of planetary boundaries, I think it’s an extremely useful one, because when world leading ecologist Johan Rockström and many, many other leading ecologists got together, they asked the question in specificity. What are the major challenges coming from humanity’s impact on the physical environment? Can we identify those challenges? Can we quantify them? Can we identify what would be safe limits for human activity so that we can begin rather urgently because we’re late to this.

611To redesign our technologies and our economic growth dynamics so that we can have economic improvement while staying within the planetary boundaries. You’ll recall the picture that we looked at of the planetary boundaries around this circle. And I want to say a few words about each of these so that we can begin to look deeply at the question of how to reconcile growth and these various environmental threats. The first of the challenges and the biggest is climate change.


This is being caused by humanity’s use of particular technologies. Especially fossil fuels and the way we use land and grow animals and food that produces atmospheric change in the form of rising concentrations of a few particular gasses. Carbon dioxide is the most important of these. Nitrous oxide, methane and a few more industrial chemicals are the greenhouse gasses that have the property that they allow the sunlight in as ultraviolet radiation. But then, when the earth would re-radiate its heat to space, they trap energy in the form of the outgoing infrared radiation and thereby warm the planet. So these greenhouse gases are very particular molecules that have the property that they absorb infrared radiation.


And so when their concentration in the atmosphere increases, that warms the planet. It’s because of these greenhouse gases that life is possible in the way we know it, because that envelope of the atmosphere has made the earth warmer than say, the moon, which lacks an atmosphere. And is very, very cold as a result. But at the same time, if we perturb the greenhouse gas concentrations, raise them by raising the CO2 or the methane or the nitrous oxide in the atmosphere, then we endanger ourselves and other species. The second of the planetary boundaries is related, ocean acidification. This also comes from carbon dioxide in the atmosphere which is increasing because of human use of coal, oil, and gas. The oceans are being acidified, made more acid, by the fact that the carbon dioxide in the atmosphere dissolves in the ocean producing carbonic acid. And because of this acidity, various kinds of animal life, corals and shellfish and lobsters and very small plankton that also have these external shells made of calcium are threatened by the increasing acidity which makes it hard for the species to make their protective shells. Now, the pH of the ocean has already decreased by 0.1 unit on the pH scale from zero all the way to 14, the least acidic or basic end of the pH spectrum. A change of 0.1 in the pH oceans doesn’t seem like all that much. But this is a logarithmic scale. So, what a decline of 0.1 signifies is an increase of protons in the ocean of 10 to the 0.1. Or about 0.3, 30% increase of acidity in the ocean already with a lot more to come. If you look at this map of the ocean, you can see the changes that are already being noticed on average in different parts of the world.The oceans are not uniformly becoming more acidic. That depends on ocean dynamics. But the shading of this colored map shows that we’re already in an environment on a trajectory of dangerously rising ocean acidity. The third of these planetary boundaries is ozone depletion.

We learned a while ago accidentally, but thank God, we learned it, that certain industrial chemicals, those that were used at the time for refrigeration, mainly. Chlorofluorocarbons, or CFCs, when put into the air, would rise into the upper atmosphere, dissociate, and the chlorine in those CFCs would then cause the ozone layer in the upper atmosphere to dissociate. And a famous, horrifying finding was that there developed a big hole in the ozone over Antarctica. And when that was discovered by satellite of course people were rightly terrified. Because the ozone layer in the upper atmosphere protects us from too much ultraviolet radiation, saves us from skin cancer and many other harms. And humanity realized that this planetary boundary was already being crossed, the ozone was already being depleted unwittingly by us. This is what’s so frightening, we didn’t even know it until some brilliant atmospheric chemists unveiled the mechanisms by which these chlorofluorocarbons deranged and destroyed the ozone level.

614The next of the planetary boundaries is the heavy human caused loading of nitrogen and phosphorus. When farmers grow more food, you’ll recall that they put soil nutrients into the soil as organic fertilizers and as chemical fertilizers. Either way, incidentally, the nitrogen goes into the soil, some of it gets taken up by the crops. But a lot of it runs off the farm into the water, into the groundwater, and it collects in the rivers, and especially collects in the estuaries, the point where rivers meet the ocean. And that heavy pollution of nitrogen and phosphorus coming mainly from fertilizer use is creating a tremendous amount of ecological destruction.

We’ll have a look at that shortly. The next big challenge of planetary boundaries comes from our overuse of fresh water resources. We need fresh water every day to stay alive. Our crops need fresh water.


Of the total amount of fresh water that humanity uses, about 70% is used for agriculture, to grow our food. About 20% is for industry. And about 10% only, interesting enough, is for our household use, for hygiene and sewerage and, and and the rest. We use so much water, especially for our food production, that we are depleting very, very important sources of fresh water. For example, in the United States, in India, in China and in other parts of the world, we’re drilling for water in, in ground water aquifers, we are taking the water out, using it for irrigation. But taking the water out at a much faster rate than the water is being replenished by rainfall, and then by the water percolating back into the groundwater.

We’re depleting the groundwater. When it runs out, disaster. And that’s happening in many places in the world and will happen in many other places in the coming decades unless we are much more efficient in our water use. To grow food to feed our animals of course, humanity uses a massive amount of land. We also use land for our cities, for our parking lots, for our streets. But actually the urban areas, even though they seem to dominate, are only a few percent of the total land area on the planet. The farmland and the pastureland and the timberland that we use for forest products is a much, much larger proportion of the total land area. And humanity has been grasping over history for more and more land, more and more pasture land, more and more crop land. After all, the human population as we know has increased roughly ten times since the Industrial Revolution. That requires a lot more farmland to feed the 7.2 billion of us. The problem with that is that we share this planet with other species and as we grasp this land for our farmland, for our pasture land, for our timber land for our palm oil plantations and many many other uses.


We are literally chasing the other species away and off the planet into extinction in many cases. Our land use is having devastating consequences on biodiversity. The next category identified is aerosol loading. Small particles put up into the air because of industrial processes, or households that are burning coal into keep warm. And creating tremendous amount of air pollution, very damaging for the lungs. Claiming many, many lives per year. And with a heavy impact also on changing climate dynamics. Then there’s a very broad category of chemical pollution. Our petrol chemical industries, our steel industries, mining industries, not only demand a tremendous amount of land and water for their processing, but they add a tremendous amount of pollutants back into the environment. Many of these pollutants are persistent, they, they last in the environment, they accumulate, they can be very deadly for humans, for other species. And the range of chemical pollutants is so vast and the human and animal and plant health consequence is so large that it’s absolutely impossible to summarize, except to say that the problems are horrific in many places. China, the world champion of economic growth over the past 30 years, has also become the champion of polluted waterways of major cities, because of the extent of the heavy industrial processing.

And this all sums up to a final category of biodiversity loss. The death, the extinction of other species. We’re killing more animals and plants than we even know, than we’ve even met and catalogued scientifically, because we’re chopping down rain forest, poisoning environments, acidifying the oceans. Creating so much pollution and poisoning. That species are disappearing even before we’re able to identify and catalogue the millions of other species that share the planet with us and that we share with them. We are not stewards of global biodiversity right now. We are posing absolutely profound challenges. And when it comes to biodiversity loss, one could say that all of these planetary boundary threats, the acidification, the climate change, the land use patterns, the pollution, they’re all contributing to the loss of species, probably by the millions. It’s actually hypothesized, shocking as it may seem, that humanity is now causing the sixth great extinction wave of the planet earth. The other five, the first, for example, 440 million years ago. The next one, the second, 365 million years ago and so forth, weren’t caused by any species, weren’t caused by human beings, since we weren’t there. These were natural dynamics, whether it was, asteroid hits or whether it was the internal dynamics of the earth itself. These were natural processes. This sixth mega-extinction is not natural. It is the result of one species, that would be us, causing so much damage on the planet that we are putting millions and millions of other species at risk. And, since we depend on those other species, of course we are putting ourselves at profound risk. We are also creating a hugely unstable environment.


My colleague, professor James Hanson, recorded the extreme heat events on the planet from the 1950s till now shown in this series of maps. If you look at the map for 1955 and look at the dark red areas, you see a few places on the planet where there were heat waves in the June, July, August months of the year. And when you see those, you see that they were very particular places such as in, in Canada. Because of climate change, the number of those red splotches on the map which signify extreme heat, in that location, unusual to a massive extent for that locale, has been increasing in frequency very dramatically. You look at the map of 1955, just a couple of red regions. Have a look at the map of 1975, 20 years later, now there are a few more dark red regions of the map signifying places where extreme heat waves gripped those places. But, now jump ahead another 30 years or so to 2006 or 2007, suddenly the map is all red, it seems. The planet has been in engulfed by what was an extraordinary shock 30 years ago becoming common place now. We all know it, we’re feeling our own heat waves wherever we are. And being amazed year after year as new and very uncomfortable and often very dangerous records are set in very high temperatures gripping different parts of the planet each year. But what these maps are showing is that the frequency of these extreme events is absolutely shocking. Well, these are the planetary boundaries that have been identified. We know that we are already pushing against the limits. A

nd our question, in the coming analysis, is how can we think that that growth that we’ve been trying to decipher and promote can be reconciled with environmental sustainability and staying within these planetary boundaries when we already have so much challenge. That is our question, as we now delve more deeply into the intersection of economic growth and planetary boundaries.