Arquivo de etiquetas: Energia

Antropoceno XXXIX – Caminhos de transição: a energia

For the world to develop within a safe operating space of planetary boundaries one of the grand challenges is a global transition to a renewable world energy system. This is a double challenge because it’s not only about biophysical operating within a safe operating space, it’s the recognition, shown in this graph, of the tight connection between energy use in the world and economic growth. In fact there’s a linear relationship so far between growing economies and growing energy use. And that is projected to continue, even though in [at] a slightly lower pace, up until mid this century. 741

There’s also the recognition of how our past looks like. And just check out this development of the extraordinarily rise in energy use since the great acceleration started in the mid-1950s. And what you see here is the growth of coal, and particularly oil and gas, as the predominant sources of energy.

So one simply has to recognize that if we’re seriously talking about sustainable development we can not escape the fact that we need not only energy, we will need more energy in the future if we take an ethical responsibility for the wealth of a world of 9 billion people.

The challenge, thus, is a transition into a zero coal or non-fossil fuel-based economy in the future. What may help us here is in fact not only technology advancements in renewable energy, which is remarkable, it’s also the fact that we are approaching or are at peak of many of the most cheap fossil fuel energy sources.742

And in this graph you see that already from the mid-’80s, 1980s, and onwards we have actually bypassed the point of access to cheap sources of oil. This has a risk of course of a transition to other cheap but even more polluting sources, such as coal, and the transition we’re seeing today in terms of fracking for natural gas, which is methane, which is a very powerful greenhouse gas. But overall it shows that however you twist and turn the analysis the era of cheap oil is behind us, which may help us also as an incentive to a transition to renewable energy systems.

But a very important challenge in terms of this transition is to recognize that not only is there a linear relationship between economic growth and energy use, what has enabled our quick economic growth is that energy has been cheap. And if you look at a key parameter in this regard called energy return on investment, meaning how much value do you get out for each input of investment into your extraction of energy.743

We have been privileged, in fact enormously privileged, of having a very large return on investments on oil over the oil era, since the early 1930s and ’40s with energy returns on investment often exceeding hundred in the early days of the oil bonanza, and today moving down quickly to levels of 30 to 15.

But look at what happens with, for example, nuclear energy, biomass, photovoltaics, oil sands, with energy returns on investment being very low. And in fact this really worries scientists and analysts because we’re not even sure how to operate a world economy with energy returns on investments going below 10 to 15, so another reason to really explore innovative solutions in the space of renewable energy systems.

And just look at this trajectory into the future indicating that we’re moving increasingly towards a point where we bypass this magical level of energy returns of investments below 10, which again means that energy becomes so expensive that it may no longer contribute to the economic growth we’ve seen in the past.744

So these are sharp reminders that the planetary boundary analysis showing the necessity to stay within a sustainable global carbon budget is coupled to the recognition also that the polluting, dirty and climate-destroying energy systems we have today are also becoming less attractive because they’re becoming more and more expensive, and less and less efficient in delivering to the human endeavor of economic growth.

Now if you look into the future the drama is equally stark. This is an analysis from the Global Energy Assessment showing that even in a transition to a sustainable energy future, here illustrated by the label Global Energy Assessment efficiency, or the Global Energy Assessment mix, which if you look carefully shows a very rapid rise in renewable energy systems and a contraction in the use of particularly oil and coal, but still the overall picture is growth of energy demand in the world.

So in 2050 the estimate, as you see even if we have very high optimistic projections on energy efficiency, we’re still seeing a future where we’re moving from our current use of roughly 500 exajoules of energy to a future of 600, 700, 800 exajoules of energy in the future. So a reminder again of the enormous challenge.745

Now what’s the solution to this? Well, most analysts would agree today that the long-term future is a future world basically or predominantly supplied from solar energy systems. We’re not there yet, but look at these graphs, which originate from fantastic work among energy researchers at Chalmers University in Sweden, showing the exponential rise in photovoltaics and wind power in key countries in the world.

And what you see here is that up until 2002-2003, we had a very slow rise in technology and uptake of these renewable energy systems. And then we have a takeoff and exponential rise where for example today countries like Germany, after all the world’s fourth largest economy in the world, if you wake up a Saturday morning in Germany you’re likely to get in the order of 30-40% percent of your electricity from wind and sun. So we’re starting to see solar and wind systems coming to scale also in the large economies of the world.

So there’s promise that this transition is not only necessary, but in fact possible to achieve at economically competitive rates, but also desirable. because they provide clean energy systems with very high benefits for health and also interestingly in a much more democratic way.746

Many of these energy systems are provided from small-scale distributed households, farms, small businesses, that produce their own energy and buy and sell energy to a flexible energy market. That’s why, to close, I believe that journals like The Economist even put at the front page of one of their recent issues a dinosaur and an oil pump in their hands, making the analysis that in fact those who invest and keep investing in dirty, risky, undemocratic fossil energy sources are the dinosaurs in terms of meeting the demands and needs and opportunities in the future. While a transition in terms of energy in a safe operating space can be, should be, and must be the opportunity for a much more clean, modern energy system for a world that of course will demand more energy to truly achieve sustainable development, but which needs to be sustainable.

7.4.2.. The role and risks of technology in the anthropocene

This will be about technology, and this is one of my favorite topics. When we talk about the Anthropocene, I think we seldom miss the point that so much of what happens in the Anthropocene, and the fact that we might be in the Anthropocene, happens through technology; it’s been through technology.

And one of the favorite examples that I take up with some of my students and some of my talks is this example. A couple of years ago an NGO and a couple of researchers discovered a new monkey type in the Amazon called the Titi Monkey, a new type of Titi Monkey. And they needed money to promote conservation efforts for the monkey. So they decided to make an option, an online option to sell the naming rights of that monkey. So they did that, and it was quite successful. They managed to get $650,000, and the company that won that auction was an online casino called

So officially gets to name the monkey, so the official name of this Titi monkey is actually Titi Monkey. And it has a Latin name called Callicebus aureipalatii, which I believe means golden palace.

And it’s quite a bizarre example, of course, but I find it quite intriguing that we’re modifying – we’re affecting nature at such a deep level that we’re even auctioning out the naming rights of a monkey species to an online casino.

I think the three interesting topics in here that are more general that this quite bizarre example. One deals of course with biodiversity and how we protect biodiversity. And there’s another issue related to politics of course. I mean where are we, is this a good idea should we really pull in private funding in this way? And giving – selling out naming rights in this way? And of course the third topic [is] about technology. Who would have thought 10 years ago that an online casino would have bought the rights to name this particular monkey?

Now I think this really brings us to an illustration of the next generation of environmental challenges in the Anthropocene, and new governance challenges facing us.

This is a quote from a New York Times article from one of the researchers a paper showing that the west Antarctica ice sheet was collapsing irreversibly, risking to create very large increases in sea level rise. And the quote from the scientist of course is, “This is really happening. It has passed the point of no return.” So it brings us back to the issue of tipping points and new risks.

Once these news were out there of course you hear discussions about trying to stop this from happening through technology, so essentially geo-engineering interventions. Sending out ships to spray out salt particles in ways that would make clouds whiter and then cool down the area, and hopefully, ideally, theoretically, cool the area down so much that you could stop the glaciers from collapsing. And of course this is just one example of many, many of these tipping point elements. This is a famous image from Tim Lenton’s work on tipping points in the Earth system.

And the issue here is of course if there are tipping points, and some of these might be a very, very large scales, and affect the Earth system as a whole, are there ways by which we can use technology to stay away from these, or mitigate these, or adapt to these in smart ways? And of course that triggers a lot of controversy and political conflict. And geo-engineering is a brilliant example of the interplay between risky tipping points, technology, and technological interventions and the political conflicts and debates those sort of discussions trigger.

And it’s not just about climate. I mean I just gave you a climate example. Some scientists propose that you would need to promote a new generation of conservation efforts that are more active to cope with climate change in ways to protect coral reefs.

So one example of tangible interventions were to create artificial coral reefs, or create big umbrellas, or to protect and cool down coral reefs, to create gene banks, etc., etc. Another interesting observation is from a workshop that was a few years ago in the UK where researchers and NGOs got together to discuss whether we can use synthetic biology to promote conservation and to maintain biodiversity. And there’s an emerging discussion about something called the extinction, so essentially using DNA from extinct species and use that DNA to bring these species back, and would that be a way to maintain and protect biodiversity?

Highly, highly controversial of course, and quite intriguing. I think one of the general reflections and reactions to this from the public and other scientists would be, but are we allowed to do this? Doesn’t this inflict on the precautionary principle? Now the precautionary principle that states that we shouldn’t do anything that might create harm. I mean that would be the popular perception of that.

But in fact if you look into international agreements, such as the Commission on Biological Diversity, it states something different. It says that, and I’m goint to quote here, “Where there is a threat of significant reduction or loss of biological diversity, lack of full scientific certainty should not be used as a reason for postponing measures to avoid or minimize such a threat.” So essentially actors, NGOs, a few researchers, used the precautionary principle as support for these sort of intervention[s].

And is that the proper framing of the precautionary principle, or should we have a more moderate interpretation of that? And what would that look like? So I think that’s just a simple illustration of the sort of challenges that tipping points, emerging technologies, get mixed up in a way that create[s] new political controversies and new governance challenges.

The Basics of Climate Change Science I

The Earth’s Energy Balance

We will be talking about the basics of climate science. We need to build on these basics in order to understand our choices about deep decarbonisation and other actions related to other greenhouse gases in order to understand why, how, when, at what pace we should be reducing emissions of greenhouse gases in order to stabilize the concentration of greenhouse gases at safe levels. What’s safe? What’s the relationship between the greenhouse gases and climate?

That’s the purpose of this lecture: to give us an introduction to this very rich, very sophisticated a hundred ninety years of science, and in the first chapter I’m going to talk about the Earth’s energy balance.

This goes back as we’ve already noted about a hundred ninety years to Joseph Fourier who first realized that the Earth’s average temperature would be determined by a kind of balance or equilibrium between the incoming energy of solar radiation and the outgoing energy that the earth radiates back to space.211

That’s when the Earth’s temperature is at a level such that the incoming radiation and the outgoing radiation are in balance. That we have an equilibrium, a place of stationary temperature for the Earth and understanding how greenhouse gases affect that balance has been the core of climate science since Fourier’s very creative understanding of this process since the 1820. This diagram that you’re looking at shows in very simple, schematic terms this global energy balance.

At the center of the graph is the center of the whole issue and that is that the Earth receives radiation from the sun, that the radiation from the sun warms the planet. If we look at the amount of radiation at the top of the Earth’s atmosphere that’s determined by the distance of Earth from the Sun and from the sun’s energy in radiative flux and we can measure that just as we do with our lightbulbs in watts: that’s a unit of power and watts per area or watts per meter squared is the standard unit that scientists use to measure the incoming solar radiation and what you can see from this diagram is that on average given the solar constant output we have an average amount of about 341 watts per meter squared at the top up the atmosphere.

Now as this incoming sunlight comes in, that’s mainly how we experience this electromagnetic radiation is sunlight, that is radiation at a certain frequency much of which is within the visible range, part of that is immediately reflected, the part that you see towards the left hand side bouncing off clouds back up into space Another part of the incoming solar radiation is reflected by the surface of the Earth.

When the sunshine comes in and hits an ice sheet, say the Greenland ice sheet, or hits sea ice floating in the North Atlantic and and the sunshine just radiates, is reflected in re-radiates back out into space that is reflected on the left hand side. But of course a certain amount of the radiation doesn’t bounce off the clouds back into space and doesn’t bounce off of the earth’s surface but is absorbed by Earth and warms the planet. And the basic idea is that any body, including the body of planet Earth, when it has a certain temperature itself radiates energy.212

This is a basic fact of physics This is a basic fact of physics and the basic study of it is called the study of blackbody radiation and in fact the Earth absorbs radiation from the sun. You see that from the center to the left of the diagram but then it radiates energy back into space, and one of the most interesting and basic facts of all of this is that the incoming radiation is  in the form of visible light or ultraviolent radiation, UV radiation, and that is relatively short wavelength, high-frequency radiation, and the radiation that the earth itself causes by it being a warm body is a bit longer wavelength called infrared radiation. So the incoming arrows are visible sunshine for example and the outgoing radiation on the righthand side of the diagram is infrared radiation.

That’s gonna play a very very key role in our understanding of climate and the greenhouse gas affect because the basic idea is that the greenhouse gases (carbon dioxide, methane, nitrous oxide, some industrial chemicals) are basically transparent to the incoming solar radiation, they allow it to come in, but they are not quite so transparent to the outgoing infrared radiation from Earth itself, the longer wavelength. In fact, they absorb that infrared radiation in part, and it’s that absorption of the Earth’s own infrared radiation that traps energy that otherwise would go out to space. It traps energy and creates a kind a blanket or the greenhouse effect if you will that makes Earth warmer than it otherwise would be.213

You see that in this simple diagram by the fact that we have surface radiation aiming back towards space and then you see that some of that circles back after it hits the greenhouse gases in terms of what’s in this diagram call the back radiation towards the plane. Now in balance or in equilibrium the Earth’s temperature is determined such that the arrows coming in equal the arrows going out, and if we were to have no greenhouse gas in the atmosphere if we were a a planet without an atmosphere, if we were like the moon, then there would be only radiation going back out in space, none of that back radiation going from the greenhouse gases back to earth, and the balance would be reached at a relatively low temperature of the planet.

Indeed, the temperature would be roughly 33 degrees Celsius lower than it actually is on the planet. The actual temperature of Earth on average is about 14 degrees Celsius. If we didn’t have the greenhouse gas cover we would be roughly 18 degrees minus, negative 18 degrees Celsius, instead of the actual 14 degrees Celsius that we have, and that is the difference of having a greenhouse effect that traps some of the outgoing infrared radiation and not having an atmosphere with that greenhouse effect that would just allow the radiation to go back into space directly. Now this diagram’s filled with all sorts of complications  and this is why be underlying science of the greenhouse effect has many challenges.214

How much of the incoming radiation actually reflects back to space? That depends on cloud cover, that depends on the surface of the earth, how much is ice for example, how reflective is the Earth’s surface, what’s called the albedo of the Earth. If ice melts then what used to be reflected back into space of the solar radiation now gets absorbed and you get a kind of feedback effect where a warming up the planet melts the ice, reduces the reflectance of the incoming radiation, increases the absorption of the incoming radiation, and further warms the planet. And many other dynamic effects are present here meaning that your simple simplest calculations can’t quite do the job telling us precisely how an added level love greenhouse gas is going to change the radiative  balance and thereby change the equilibrium temperature but this simple illustration is very very helpful in explaining the basic greenhouse effect.

Now to move one step more deeply, it’s important to understand this specificity of what makes a greenhouse gas and that is shown by what’s called a radiation spectrum of both the incoming radiation and some of the absorption of that spectrum. Light comes to Earth from the Sun or electromagnetic radiation comes to Earth across different wavelengths and so we go from very very short wavelengths on the left handside of the spectrum to very long wavelengths on the righthand side from ultraviolet towards the left hand side of the electromagnetic spectrum towards infrared and long wavelengths on the righthand side of the spectrum, and the amount of energy that is in the solar radiation is shown essentially by this spectrum of the sunlight and it’s that dark line which shows the radiation spectrum.

How much of irradiance, how many watts per meter squared is coming at each wavelength of solar radiation. You can see that the peak of that radiation is in what’s called the visible range of the electromagnetic spectrum. Visible because that’s what we see that’s the light we see. We don’t perceive ultraviolet or infrared, that’s outside of the visible range for human beings, not for some animals but for us, and so most of the energy, most of the watts per meter squared of the incoming solar radiation is in the visible range.215

Not so for the outgoing radiation from the planet, and this is a part of physics that comes from that theory of blackbody radiation called the Stefan-Boltzmann equation. It basically says that a very hot object like the sun will have more irradiance at the high frequency or low-wavelenth end of the spectrum whereas a cooler body like the Earth will have more radiation at the long-wavelength or infared part the spectrum.

So since Earth is a lot cooler than the Sun, we radiate at the righthand side of the spectrum. Now why does that matter? It matters because certain compounds, these are the greenhouse gases, absorb infrared radiation. That’s part of their chemistry, part of their quantum physics. The compounds that absorb radiation all have more than two atoms so O2 or N2, oxygen as it is in the atmosphere or nitrogen, dinitrogen, as it is in the atmosphere, is not a greenhouse gas.

To be a greenhouse gas you need to be 3 atoms or more. That allows the atoms to jiggle in particular ways and to absorb the infrared radiation So CO2 was three atoms, 1 carbon, 2 oxygen atoms. Nitrous oxide, N2O, methane which is 5 atoms, carbon and 4 hydrogen atoms all have configurations in their bonding that allows them to or makes them absorb infrared radiation and by absorbing the infrared radiation, they absorb the energy that otherwise would radiate to space.

They warm the planet and so one can see shown in this diagram, the so-called absorption bands of carbon dioxide and water. They’re to the right hand side of this figure. What does that mean?

They absorb longer wavelength electromagnetic radiation, the kind that Earth radiates, they don’t absorb the kind of radiation coming. The long and the short of it, they are transparent to the visible sunlight that we see when we go out on a sunny day but they absorb the infrared that we don’t see that the Earth is re-radiating as a warm body at an average of 18 degrees Centigrade and it is precisely the absorption of the infrared radiation that keeps the planet at the average of about fourteen degrees Celsius rather than the minus 18 degrees Celsius that would prevail if we didn’t have the greenhouse effect. And what we know is what Arrhenius told us back in 1896 and that is that as we increase the concentration of carbon dioxide or methane or nitrous oxide or other greenhouse gases in the atmosphere we’re going to get a warming.

We can measure the temperature, you have to do it very carefully in weather stations all over the world, my colleagues at the Goddard Institute of Space Studies, NASA’s leading scientific outfit for measuring the Earth’s mean temperature and one of the major enterprises in the whole world for this has produced very very careful data on changes of Earth’s temperature that’s illustrated by this graph.216

Now in this particular graph, the 0 line is the Earth’s average temperature for the years 1951 to 1980 and what you can see is that by our period by the years after 2010 or so, we’re at about .6 of 1 degree Celsius or about one degree Fahrenheit warmer than the average of 1951 to 1980, and you can see from this upward slope that the Earth is warming warming. It’s not warming every year, there’s a lot of variability. In fact there are even episodes, look at graph from around 1940 to around 1980, where there wasn’t a lot of warming and that raises a lot of questions CO2 and other greenhouse gases were rising but the temperature wasn’t rising all that much so that poses a question of what else is happening but the general direction is unmistakable and it instead of taking an average of 1951 to 1980, we took the average temperature before the whole industrial revolution started we would see that we’re close to a one degree Celsius increase of temperature now, about .9 of one degree Centigrade and this is of course the upward slope that is so frightening because it’s already disrupting the planet and it will cause a lot more disruption. Now let’s turn in more detail to the specific greenhouse gases that are responsible for this human-induced change. That will be the topic of the next lecture.

Growth within Planetary Boundaries III

The Case of Energy

Of all of the problems of reconciling growth with planetary boundaries probably none is more urgent and none is more complicated than the challenge of energy. Remember that the whole world economy grew up, starting with the steam engine, then the internal combustion engine, the gas turbine as a fossil fuel built world economy. Fossil fuels, coal, oil, gas, have been our friend. They have been the basis on which the modern world has been built. And indeed until James Watt in 1776 came along with his steam engine, there was no way to even think about sustained economic progress. Where would the energy for industry come from? Every time industry would start to develop in the pre-steam engine age, so many trees would be chopped down to feed the boilers that the limits of industrialization were very quickly reached. It was fossil fuels that allowed the breakthrough to the era of modern economic growth. I emphasize this because that history reminds us of how deep the challenge is. Right now fossil fuels are not our friend because when coal, oil, or gas is burned the carbon that is the basis of those fossil fuels combines with oxygen and produces CO2, carbon dioxide, which is emitted into the air, which is the main greenhouse gas warming the planet, changing the climate, and endangering humanity and other species. And so what has been the key at the very core of the world economic growth is now at the core of our major problem. Well, you might say use less energy, but it’s not so simple.

Because as a physicist will remind us, what is energy? Quality energy is the ability to, to work. Any useful work in, in economy depends on energy. Sure, we waste a lot of energy in the form of release of heat or friction or driving cars much larger than they need to be or poorly insulated buildings. So energy efficiency is clearly part of any solution for sustainable development. But the world needs energy resources, will use energy resources, and the use of energy, even with a substantial gain of efficiency, is likely to increase in the aggregate as the world economy expands by factor three or by factor four as we have just seen. And so we have a problem. More energy is needed. The traditional forms of energy, the fossil fuels of coal, oil, and gas, can’t do it for us because that would create a massive intensification of the climate change problem. How big of an intensification?


That’s what I’d like to discuss, so that we get some parameters of where we are and where we’re going. This graph shows again on a logarithmic scale on the horizontal axis and on the vertical axis the income of different countries and the primary energy use of those countries, the energy consumption. Total energy use by country would include the fossil fuels, it might include wood burning, hydroelectric power, geothermal energy, wind and solar power, nuclear power or some other forms for instance biofuels. And what is done in this graph is for every country in the world to measure first the total output measured as the gross domestic product, and then to compare that with the total primary energy use. Which can be expressed in a number of ways, in units of kilowatts, or kilowatt hours, it can be expressed in tons of oil equivalent energy where, you take the amount of energy in one ton of oil, and then for all the other kinds of energy, whether it’s coal or gas or hydro and so forth, you look at the amounts of, of energy available from that resource and convert it as if it were tons of oil that had that much energy potential. And then express all the different energy sources with these conversion factors as a tons of energy equivalent amount of primary energy use. What you see when you graph the total output of an economy versus its energy consumption is essentially a straight line, though of course the countries don’t fall exactly on this upward sloping line. What this line signifies is that a doubling of the size of an economy tends to be associated with a doubling of primary energy use. Energy use scales alongside in proportion and in relatively constant ratio with total size of the economy. So, as the economy grows the energy use will tend to grow along side it. Save for break those in technology that allow for greater energy efficiency.

Lets look quantitatively at how much energy we use and what that implies for how much carbon dioxide we therefore emit into the atmosphere and what that implies for how much climate change we’re causing.

If you look at the amount of energy use by country you find that, roughly speaking, this is on average because countries differ, but they don’t differ all that widely. For every $1,000 of total production in the economy, the total energy use expressed in tons of oil equivalent tends to rise by about 0.19 tons of oil. What is 0.19 tons of oil? These are metric tons. So, a metric ton is 1,000 kilograms. So, 0.19 of a metric ton is 190 kilograms. So let me put it again this way. $1,000 of production, on average, expressed in, $2,005, let me add one more, parentheses, is associated with about 190 kilograms of oil use, or an equivalent amount of energy contained in coal or natural gas or one of the other non fossil fuel forms of energy. That gives us the scale of how much energy we use for each $1,000 of production. Now, if you look at the mix of, the energy sources in the world, mostly fossil fuels, but also some nuclear power, some wind, some solar, some some charcoal from trees some biofuel say from sugar cane converted to ethanol for automobile use as in Brazil. On average, every ton of oil equivalent energy is equivalent to about 2.4 tons of carbon dioxide emissions. In other words burn a ton equivalent of energy, and you put up more than two tons of CO2 into the atmosphere.

How much CO2? That depends on exactly which energy source you’re using. If it’s nuclear power, zero, because nuclear power is not a fossil fuel, and therefore nuclear power does not by itself create carbon dioxide emissions. If it’s coal, it’s higher than that average because coal, being almost all carbon with some impurities, when it burns, creates CO2 with little other energy created by the coal. And so coal creates the most carbon dioxide emissions per unit of energy of any fuel. Gas, and natural gas and oil emit less. So coal for a ton of coal burned, you get about four tons of carbon dioxide emitted into the air. For a ton of I should say not for a ton coal but for a, an amount of coal equal in energy to one ton of oil. That’s the right way to say it. You get about four tons of CO2 emission. For one ton of oil, you get about 3.1 tons of CO2 emission. For the amount of natural gas equivalent to a ton of oil in it’s energy content, you get about 2.4 tons of CO2. And for hydroelectric power, for solar power, for wind, zero.

632So, you can see why those energy sources are highly desirable from the point of heading off climate change. Let’s summarize again.Each $1000 of production requires a 190 kilograms, or 0.19 tons of oil equivalent of energy. And each one ton of oil equivalent on average is associated with 2.4 tons of CO2 emissions. So let’s do the arithmetic. Expressed in $2,005 used for this illustration, the world economy at 2010 was at about $68 trillion. $68 times 0.19 tons of oil equivalent per $1,000 times 2.4 tons of carbon dioxide per ton of oil equivalent energy turns out to be 31 billion tons of CO2 emission, and viola, that’s what the world released into the atmosphere in 2010 by virtue of its fossil fuel use.

So you see we can measure the size of the economy times the energy use per unit of economy, per $1,000, times the amount of CO2 released per unit of energy. And the result is a very big number, 31 billion tons of carbon dioxide released. We also put CO2 into the atmosphere as humans in other ways. We chop down trees. And when we chop down trees, the carbon that was stored in those trees is released into the atmosphere if the trees are burned or, or decay. And so carbon that was sequestered biologically is released into the atmosphere as well. That adds a few billion tons of carbon dioxide emissions in addition to those caused by fossils fuel use. Little more arithmetic. For every ton of CO2 put into the air, just a bit less than half of that stays in the air, because some of the CO2 dissolves in the ocean, some of it gets sequestered in plants and trees back on Earth. And so, of the one ton that’s put into the air, approximately 0.46 of that or 46% of what’s admitted into the air, stays in the air. And the other 54% typically is stored in what are called natural sinks, the oceans or the land.

Now, that means that if we put 31 billion tons into the air, a little over 14 billion of those tons stayed in the air. Is that a lot, 14 billion tons, for our big atmosphere? Well we can make that calculation.

We can look at the total volume of the atmosphere, how many molecules are there. How many molecules of CO2 have been put up in those tons? You have to get out your chemistry text to do that. And what you find when you do that is that for every 7.8 billion tons of carbon dioxide put into the atmosphere, the concentration of carbon dioxide in the atmosphere rises by one part per million. So that’s the translation factor. To raise the CO2 concentration in the atmosphere, which is filled with nitrogen and oxygen, and many other mole-, types of molecules. To raise the CO2 by one molecule per each million molecules of all kinds in the atmosphere, you have to put into the atmosphere 7.8 billion tons.

So this gives us now a quantitative sense of what we’re doing. If we have put 14.2 billion tons staying in the air, and 7.8 billion tons raises the carbon dioxide concentration by one part per million. Then the amount that we emitted into the atmosphere in 2010 from fossil fuel use, raised the, carbon dioxide concentration by about 1.8 parts per million or, nearly two molecules for every million in the atmosphere were now CO2 it raised in CO2 concentrations.

Is that a lot? Yes.

Is it frightening? Yes.

Let me show you why. We look again, at a graph of the concentration of CO2 in the atmosphere on the planet Earth, over hundreds of thousands of years. And the concentration of CO2 fluctuates for normal process, even putting humanity out of the story, over geologic time these levels of CO2 rise and then fall and then rise and fall as part of the long run carbon dioxide cycle. And that cycle is driven in important part by systematic changes of the earth’s orbit. And if you look at this reconstruction of the carbon dioxide concentration of the atmosphere over the last 800,000 years starting all the way to the left-hand side of the graph, the first peak you see is the carbon dioxide rose to a little bit over 250 parts per million. Then it fell to under 200 parts per million. Then around 700,000 years ago it rose again to nearly 250 parts per million and then it fell again, then it had another peak at 600,000 years ago, and so forth. So you go up and down, up and down, driven by natural changes of the Earth’s orbital cycle, but then as you move to the right that means coming closer and closer to the present on this graph. Suddenly, something really weird happens. Instead of going up down up down up down, it suddenly goes up, up, up, up, up, up, up. Shoot straight up. Just in the last 100 years of this 800,000 year graph. That’s humanity burning fossil fuel. Thank you, James Watt. Great invention. Great idea.

You made possible the world economy, but now look at the situation. CO2 soaring. How high does it go? Far higher than anything we’ve seen on this planet for 800,000 years, indeed for 3 million years. In 2013 it reached 400 parts per million. A CO2 concentration the likes of which we have not seen on the planet Earth for millions and millions of years. What the climate scientists tell us is, that this kind of change is consistent with a significant rise of temperatures on the planet. Indeed if we reach, say 450 parts per million of CO2, we are very likely to be living on a planet that on average is two degrees centigrade warmer than before the industrial revolution. Now two degrees centigrade might not sound like much, but it implies even larger increases of temperature in the higher latitudes and it implies massive changes of the Earth’s climate, of rainfall, of droughts, of floods, of sea level increase. So we’re talking about changes in CO2 concentrations that when translated into global warming, and into climate change more generally, are extremely large and extremely dangerous and happening now.

How fast are they happening? If we’re at 400 parts per million today, and that’s rising by about two parts per million each year, you can see that to reach 450 is just 25 years from now. My word. We can’t even change it at world energy system at, at that rate. So we’re on a trajectory that is very fast, and very troubling. And, add in to the fact that that’s assuming we stay where we are. Now think about tripling the world economy and tripling the amount of energy used, and if we do it using the same energy mix that we have right now, we’d be increasing CO2 not two parts per million, but five or six parts per million within a few decades. In other words, if we don’t change course we are on a path of extraordinary peril.

Where because of our fossil fuel reliance, we would be seeing mega-droughts, we would be seeing mega-floods, more extreme storms, more species extinction, more crop failures. A massive sea level rise over time, and a massive acidification of the ocean as that CO2 dissolves into the ocean, produces carbonic acid, and reduces the pH of the ocean. We have to change course, and we have to change course quickly. More quickly than the politicians are telling us, by far.

But there’s good news, let me not leave us in despair. We have powerful technologies at sharply falling prices for solar power, for wind power, for energy efficiency, for smarter systems that can economize tremendously on energy and shift us to low carbon means. We’re going to revisit some of those methods very shortly.