Adaptation

We’ve seen that it’s possible to reduce human emissions of green house gases substantially. The technologies are within reach. We need energy efficiency. We need low carbon electricity. And we need electrification of parts of the economy, like automobiles, like home heating, and some industrial processes, to use that clean energy from clean electricity rather than the dirty energy coming from burning fossil fuels. How do we get there? What do we do? Now, one thing must be stressed from the start. Energy is so deeply embedded in our economy, in how we do everything, in industry and transport, in our living, the organization of our cities. We can’t make that transition to low carbon energy overnight. Even if we wanted to, the only way to dramatically reduce greenhouse gas emissions in the short term would be pretty catastrophic. We’d have to close down large parts of our economy. What we’re really looking for, therefore, is a transition over the course of 30 to 40 years. Not a sudden, abrupt end of emissions. But we need to move quickly, because what science tells us is that we have to cut by half or more our total emissions by the mid-century, even as the world economy is expanding dramatically. So, we’ve gotten the hints of what to do. What kinds of policies can be used to get there? Well, let’s consider, once again, the main pillars. Energy efficiency, for example. What kinds of policies can be applied to raise the efficiency of our energy use? One standard kind of policy, which has been quite successful around the world, is to put appliance standards into effect through regulation. And places that put basic standards on automobile, mileage, per gallon, for example, or the energy use in refrigerators and air conditioners, or a shift from a heavy energy using traditional light bulb, the incandescent light bulb, to LEDs and to compact fluorescent light bulbs, can be managed by appliance standards. And quite a lot of energy saving can be accomplished at very, very low cost, or even at net economic savings. Building codes can make a big difference. And building codes are part of the normal policy, framework of any normally run city. And we know that the quality which buildings are built, the insulation materials, the ventilation properties, the placement of the cities, the use of roofs, the internal energy systems whether it’s furnaces and boilers or, or whether it’s electric power sources make a huge difference in the energy efficiency of buildings. New York City, we already have noted it as experienced a major improvement of air quality, as well a major reduction of heavy oil use through regulation of and encouragement eh, through other means and other incentives. Of a shift to much more efficient energy use. Introducing smarter grids and new metering and smart ways that the utility company meters household and then applies pricing systems to encourage households to economize on electricity use, and helps customers to be aware of options on energy efficiency can make a very, very big difference. An even bigger part of the package for in many places will come by shifting from fossil fuels entirely to zero or very low carbon energy sources. The problem so far has been that using coal to produce electricity is often the lowest cost choice. If we don’t take into account the costs of coal to society in the form of air pollution and in the form of climate change. In other words, there’s a basic economic problem that coal has high costs, not reflected in the price of coal in the marketplace. If you buy coal and burn it as a utility, you don’t pay the cost of the carbon dioxide emissions that are going to wreck the planet for everybody else. You’re imposing a cost on others not reflected in the price that you, yourself, bear in using that coal. That’s called an externality, a utility that is using coal to produce electricity is imposing an externality on the rest of the planet. And, by the way, because that carbon dioxide sits in the atmosphere for centuries, it’s imposing an externality even on generations that are not yet born. And they can’t fight back. Can’t sue the, the, the power company. Can’t protest. Can’t call on legislators to tell that power company use a clean energy sources rather than the dirty CO2. And so, we need to correct the market signals if a utility is going to choose a clean energy source like solar power or wind power. Or if it’s going to use a technology that allows it to capture the carbon dioxide that it would otherwise emit, and store that carbon dioxide safely in some geologic reservoir, a technology called carbon capture and storage. No utility is going to chose the higher price variety unless it is forced to bear the true costs of using coal, the cost to health and the cost to climate change. So, economists rightly emphasize the need for corrective pricing. For market signals to tell the truth, to say to the utility, uh-uh, coal is too expensive if you take into account its true social costs. Well, how can market prices be corrected? They can be corrected in a variety of ways. One way is simple, you put a tax on the use of coal, reflecting the CO2 emissions and the health burdens that using that coal will cost. Only companies that capture the CO2 and safely store it wouldn’t have to pay the tax on the coal. And companies that use a non-carbon source of energy, like solar power or wind power, would avoid that tax as well. So, the market signal would say, you can not get away with it any longer, using a socially costly form of energy. Because of that tax, there will be a natural incentive of companies and households and builders everywhere to economize or substitute a way from coal, oil, and gas, and move towards the alternative energy sources that are now less expensive because they don’t bear that tax. There’s another system that can be used, which is that you’re required to have a permit to emit carbon dioxide, and only a few and shrinking number of permits are given out each year. Those permits can trade, a company that has no alternative might buy permits from others. But it’s expensive to buy that permit. It’s like paying a tax, but instead of paying the tax to the government, you may effectively pay that extra cost to whoever is selling you that permit. Could be the government, by the way. So, tradable permits for emissions or taxes on carbon are two ways to correct market prices. Another way to correct market prices is what’s called feed in tariffs. The government says to a utility company or a power generator, we’ll buy electricity from you, but we’ll pay an extra high price if the electricity that you’re bringing into the system is clean. So rather than taxing the dirty stuff, you give an added incentive for power generation coming from wind power or from solar power. These are all ways to tilt the market in the right direction. They’re not the end of the story, unfortunately, because we still need to improve the technologies for using the low carbon energy. The main problem with wind power is that the wind sometimes doesn’t blow. This is an intermittent power supply. The main problem with solar power is too, nighttime and clouds, and so the reliability and predictability of solar power, and the fact that it’s only available certain hours of the day. Mean that solar and wind power and many other kinds of renewable energy need to be stored somehow, stored in batteries, stored in other solutions that are being developed right now. If the problem of storage of intermittent energy sources, like wind and solar power, can be solved at low cost, because the existing solutions are fairly expensive. Then there would be a dramatic, dramatic breakthrough in reducing the overall costs of a low carbon electricity system. All of this means that another part of the policy of decarbonizing the primary energy system is research and development. Government should be investing heavily in new technologies, for instance, in the storage of energy from inter, intermittent power sources. Or in understanding the safety and feasibility of very large scale capture and geologic storage of carbon dioxide. Again, that idea that you continue to use fossil fuels, but you capture the CO2 before it goes into the air, and you put it safely underground. One of my very brilliant colleagues Professor Klaus Lackner, is trying yet another idea which needs a lot of research and development. And that is to capture the CO2 directly, already in the air, through chemical means, and through, then to take the captured CO2 and to store it geologically. It’s another possibility. Can that be done at a low enough cost to be economically feasible? In order to tap these low carbon energy sources, though, there’s one more point that is crucial. Very often we have massive potential for renewable energy, but it’s just not where people live. And then, we need a transmission system to bring that low carbon energy to population centers. And that means that government needs to be involved with long distance transmission of low carbon electricity. That raises many technological issues and many financial issues as well. Here is one very important, I think, a potential breakthrough system that would link the great sunshine of North Africa and the Sahara desert with the energy needs of Europe. This is called DESERTEC. It’s a proposal that engineers put on the table a number of years ago to connect solar power coming mainly from North Africa and the Middle East with the very high energy use in Europe. And the solar power would be taken by long distance electricity transmission lines to Europe. Also shown here in the blue are the wind turbines. And so, this is a system that would integrate wind turbines along the coast, in general, with solar power in the desert and very sunny regions, and enable Europe to shift from a fossil fuel based electricity system to a, nearly zero carbon energy system. It’s a great plan. It requires a lot of research and development. It requires a lot of investment. But it illustrates how to make a big move to decarbonization. Here’s a map of the United States and the main message of this map shows how much potential we have for offshore wind. The northeast coast of the United States from irginia to Maine, for example, is extraordinarily windy. And if wind turbines were put up and down the northeast sea coast, just a bit offshore, there would be enough energy, roughly speaking, to provide all the power needed in the northeast of the United States. How many wind turbines do we have right now off the northeast coast? That would be zero. The permitting hasn’t been given the transmission lines, the decision, which is a public decision that that’s the way we should go, has not been taken. And this is why corrective pricing plays a role, research and development plays a role, but also political leadership. To help say to the American people or to other countries, look, we can go this way, this way, this way, we just can’t stay business as usual. We could use the great wind power on our off-shore coasts. We could use what you’re looking at here, which is a wind field in, South Dakota, where there’s a lot of wind but not too many people. So, we would need long distance transmission lines to bring that wind power from the Dakotas to the big population centers of the United States. We could decide for a massive deployment of solar technologies in the Mojave Desert in the American southwest. Again, we’d have to have transmission lines to bring the power to the big population centers. But we have enough solar energy to provide a very significant fraction of the electricity needs of the United States. Political decision. Not only market forces, but how our land and our coasts are going to be used. What’s the least risk way? What is the safest direction? How are these costs going to be shared? What is the future of nuclear power? People are afraid of it, but they should be also afraid of cold fire power plants. Nuclear power offers one way to a very low carbon economy. Cold fire power plants don’t scare people but should. Because they, more silently, out of the headlines, kill a lot of people and threaten the planet through greenhouse gas buildup. So, what are we to make of these choices of nuclear energy? Of course, this divides scientists, it divides engineers, and it divides the public in a very strong way. My guess is that we will have nuclear power, because many countries, like China and India, and I believe the United States, will continue to deploy nuclear energy into the future. The question is how to make it safe and secure. So for all of these areas of decarbonization or electrification of the energy systems of automobiles, we require lots of public investment, R&D, political decisions, building of infrastructure. In other words, choices that by 2050, we must move to a low carbon energy system. Lest we continue as we’re going and face the calamities that would be implied by that. Now there’s one more problem. I’ve indicated that we have technologies within reach, and they are getting better and better in wind power and solar power, lower costs. But technology is also not standing still for fossil fuels as well. The ability to drill for fossil fuels has also improved markedly over the last 10 years. Some people say that’s great, I say that’s very dangerous. Because it continues to feed an addiction that threatens the planet. If we improve our capacity to tap into these hydrocarbon deposits, we’re also improving our capacity, in quotation marks, to wreck the planet. And there’s a lot of this kind of technological innovation taking place in the hydrocarbon sector. The mining of the Canadian oil sands, a massive deposit of fossil fuels that were really not very accessible technologically, but now are deployable through various advances in the ability to use this kind of heavy oil. And this, again, is being deployed because it’s financially profitable. In large part because the oil companies like the utilities, like the other coal-using industries don’t pay the true social cost of the fossil fuels. Or what is now one of the most contentious technological advances in recent years. The picture shown here of so called horizontal drilling, and hydrofracking or fracking or hydro fracturing of natural gas caught in shale rock. So with this way to put drills down and then turn them every which way, and to blast rock through a high pressured solution, that fractures the rock and releases carbon dioxide. I’m sorry, releases the methane, I should say, and releases, therefore, natural gas that, that can be burned for electricity generation. We’ve expanded, again, the capacity to tap the fossil fuel reserves on the planet. But we have to ask ourselves, are we doing ourselves a favor if we’re slowing down the transition that is increasingly, urgently needed to mitigate climate change. To head off the worst disasters that will be in store if we continue on a business as usual path. We have to make choices. The world has not yet made those choices. Let’s understand that process of decision making better. What will it take for the world to agree?

Mitigation

We’re on a dangerous path. Humanity is emitting greenhouse gases, changing the climate, and threatening ourselves and other species and future generations in many, many very dangerous ways. We need to respond to this challenge. We use two terms to reflect two different ways of responding. Both of which are important. One term, mitigation, means to reduce what we’re doing that’s causing the climate to change. So we want to mitigate climate change by reducing the anthropogenic or human-caused emissions of greenhouse gases. The other term that we use is adaptation. That means learning to live with climate change as best as possible. To protect our cities from storms surges to protect our crops from high temperatures or flooding or droughts by helping to improve the quality of the seeds to have traits like drought resistance or heat tolerance or submergence tolerance in the seeds by advanced breeding of, of seed varieties. There’s a limit to how much we can adapt, because if the changes are so dramatic that sea levels rise several meters that the food supply is profoundly threatened by high temperatures and mega droughts and loss of soil moisture. We’re not going to be able to keep up with that under any circumstance. At the same time, it’s important that we do adapt, because climate change is happening, and it’s going to continue to happen even if we are very successful at mitigation. There is inertia in the warming as I’ve noted. So we are going to experience more warming in the years and decades ahead, simply as the oceans catch up with the warming already implied by the greenhouse gases we’ve put into the air. But we should expect that if we continue on business as usual, we will never be able to keep up with the extent and the dangers that we will be causing ourselves. Mitigation, therefore, is an enormous priority. How to mitigate? Well, for that, we need a careful diagnosis. What is it that we’re doing? And since we understand that we have several specific ways that were con, contributing to greenhouse gas concentrations, we have to take measures to head off those increases. Since about three-fourths of the radiative forcing is carbon dioxide, our highest priority is to reduce the increase of carbon dioxide in the atmosphere. And since most of the CO2 increase comes from our use of fossil fuels, that’s the number one item on the mitigation agenda. The second way that greenhouse gases are increasing through carbon dioxide is land use change. And so, a second item on our carbon dioxide list of actions is to head off the deforestation that’s causing the emission of CO2 by land use change. Then, next on our list comes methane. Methane is admitted in a variety of ways. We have to address each of those. Then comes nitrous oxide. For each of these human-induced emissions of greenhouse gases, we have to have a look what’s feasible, how much would it cost, what are our alternatives? What is the most cost effective way to reduce substantially the human impact on the climate system? Now, the right place to start is the with the, the carbon dioxide. And the way that scientists have usefully posed the question is, what would we have to do to carbon dioxide emissions, mainly from fossil fuels, but also from land use, in order to keep the total increase of the Earth’s temperature at two degrees centigrade or below? The answer is, that since we’ve already increased the temperature by almost one degree, we would need to dramatically reduce CO2 emissions in the coming decades. So, one recent scientific study of what this would require is shown in the graph that you’re looking at now. What you see here is a very busy picture because there are lots of possible trajectories of emissions. On the horizontal axis are the years to 2050. On the vertical axis are the tons of carbon dioxide put into the atmosphere, measured actually as tons of carbon rather than tons of carbon dioxide. Now in all of this mix of pathways, take a look at two that are most important. First, look at the red path. This is the business as usual trajectory. It says that if we continue as we’re going, emissions of carbon dioxide will be higher and higher every year. Why? Because the world economy is growing. As it grows, it’s using more energy on business as usual, that energy’s going to be fossil fuel, and the CO2 emissions will rise. What trajectory of CO2 is needed to avoid two degrees centigrade increase? That’s shown in the blue trajectory. It says while CO2 emissions per year have been rising, now they have to start falling and falling sharply. We want the world economy to grow because we want poor countries to be catching up with the richer countries in living standards. But at the same time, we want the total emissions of carbon dioxide to be falling sharply. And to put it in very general terms, what’s shown here is that, while the world economy might increase threefold by the middle of the century, the total emissions should probably fall by at least half, if not more. That means that emissions per dollar of output need to decline by a factor of six or even more. We use the term decarbonization to mean reducing the amount of carbon dioxide per unit of output, per dollar of gross world product. We need a deep decarbonization of the world economy. But since most of the carbon dioxide comes from fossil fuel, we need a sharp reduction in the use of fossil fuel, at least in the way that we use fossil fuel now. One fascinating, quite wonderful study, recently done, asked the question, so how could California, a major part of the U.S. economy reduce its emissions by 80% by the year 2050. How could California, in effect, decarbonize the California state economy? And the answer is really important for us because it’s the general principles of mitigation. Three categories of action. First, energy efficiency, get more output per unit of energy input. How can we do that? Through more efficient appliances, for example.Through light bulbs whether it’s compact fluorescent light bulbs or light emitting diode light bulbs, as opposed to our more than century old incandescent bulbs.These are examples of new technologies that allow us to get more for less. More output per unit of energy. The second thing we need to do is to shift our energy supply, our primary source of energy. Instead of using coal, oil, and gas, all of which emit CO2, we need to use wind, or solar power, or other low carbon technologies. The third category of action is to take parts of the economy where we now use fossil fuels, other than the electricity sector, convert those other sectors to electricity, and then run those new electrified sectors of the economy on electricity produced by low-carbon energy sources. So what do I mean? Well, take the case of automobiles with internal combustion engines. We know that those automobiles, instead of running on internal combustion of petroleum, can run on electricity. In fact, they can do a lot of really clever and smart things for a very safe and comfortable ride as electric vehicles. And those electric vehicles need to be charged. You plug them into a power source. And if the power source itself is a low-carbon energy producing the electricity, for instance, wind farms that are used to charge the automobiles, then we have a dramatic reduction of carbon emissions coming from automobile use. And so, by electrifying the fleet of automobiles and charging that electric fleet on a clean energy grid, we could have a dramatic reduction as well. So the point is a three part process: energy efficiency, low-carbon energy sources running our electricity grid, and electrification of parts of our economy. Automobiles or home heating or industrial processes, shifting from local uses of fossil fuels in the gas tank or in the factory or in the boiler at home, and shifting that to electricity that is on a grid of clean electricity. Well, what’s an example of clean electricity? It’s electricity that comes from fo, photovoltaics, for example. Or so called concentrated solar thermal. Both are technologies that take solar energy and convert the solar energy to electricity. Photovoltaics does it directly by the solar energy hitting certain kinds of materials that then release electrons and create an electron flow, the photovoltaic effect. First  escribed by the way it, it’s basic science by Albert Einstein in 1905. Or, by taking the solar energy reflecting it in mirrors, and heating water to a boiling point, and then using the steam to turn a steam turbine, and thereby producing electricity. Either way, you get electricity without fossil fuel and without carbon dioxide. And of course, we have many potential ways to produce large amounts of electricity. It could be solar power. It could be wind turbines, which have come down so much in cost that in many parts of the world, the windy places, they’re already cost competitive with fossil fuel generation. It could be geothermal energy where along tectonic zones where you can tap into the heat within the Earth, within the mantel. It’s possible to generate a lot of heat, which is used to boil water, turn steam turbine, and produce electricity. As is done, for instance in Iceland or now, increasingly in the Rift Valley of East Africa. Or more controversially, you can produce electricity with nuclear power. Electricity produced in a nuclear power plant does not create carbon dioxide emissions. It creates other risks fissile material that could potentially be used for weapons, or the risks of terror, or the risks of, of meltdowns. Or disaster such as hit Fukushima in Japan during their recent earthquake. Or Chernobyl, because of a mis-management of the power plant in Ukraine, back in the mid 1980s. But nuclear power already supplies a significant part of the electricity in many parts of the world, and it is a, essentially, a zero carbon electricity supply. And so, if we can move to a clean electricity grid, not dependent on fossil fuels, then we can also move to what you see here, an electric vehicle. There are many, many new models coming. Batteries are being improved. Technology is being improved. Electric vehicles happily can be a lot smarter than internal combustion engines, because a car running on electricity can also run on a lot of smart systems as well. Rather than the mechanical power, it’s electric motors linked to sensors, and even to self driving vehicles as of we know are being very actively explored and, and pursued by companies such as Google. And so, the chances of better transport and cleaner transport better home heating and ventilation through smart buildings and through smarter electrification, rather than using furnaces and boilers, make it possible to envision a very, very steep decline of CO2 emissions. When the California study added it all up, they found the way to reach that bold 80% target is, as illustrated in this figure. The baseline emissions are the line at the top, showing that CO2 emissions are on the rise in California because of growth of the economy. The preferred mitigation trajectory is the downward sloping line at the bottom of the curve. And the gap is explained by all of these ways of reducing CO2 emissions. The light blue zone shows the reductions of emissions coming from energy efficiency. The dark blue zone shows the reduction of emissions coming from de-carbonizing the energy sources used to produce electricity. Then you see that electrification in the yellow zone is moving to electric vehicles. There are also other smaller categories of turning to biofuels, for example. What is a biofuel? It’s of course using somehow a natural biologic process to produce a fuel that’s a substitute for fossil fuel. And so, there are many, many ways to mitigate, but the broad categories through energy efficiency, a clean electricity grid, and electrification have been shown by many studies to be the pillars of any successful strategy. Here’s the good news, all of these technologies are within reach. All of them have potential ability for a large scale. There are solutions, in other words, that are within reach. And we’re going to look at some of those solutions shortly, at what can be done in different parts of the world to make a very large correction in this dangerous path that we’ve been on. Now, there’s one more idea around. I’m not an advocate at all. Many people are very worried about it. Though, a few scientists are very excited. It is the Band-Aid approach shown here with the planet, with the, the Band-Aid on top of it. It’s called geo-engineering. The idea is, well, maybe we won’t really stop the carbon emissions. But we can find other things to do to compensate for the effect. One idea, it’s an actual idea, though I find it very frightening, is that while the carbon dioxide’s warming the planet, we would put up particles into the air. Sulfate aerosol particles that would dim the sunshine and actually cool the planet to offset what we’re doing with the carbon dioxide. Feed the air with one poison and the idea would be, well, let’s add another poison to kind of compensate. The problem is it doesn’t really compensate. It most likely adds some significant dangers. It doesn’t stop the increase of CO2. It doesn’t stop the acidification of the oceans. It doesn’t stop the changing patterns of precipitation. Indeed, it would have highly, highly uncertain and potentially very, very dangerous effects. But I think that the Band-Aid approach is what it is. If the bleed is so dangerous that it threatens life itself and well being on the planet, a band-aid is probably not an adequate response. And in this case, I think we should look for what’s within reach, what our technologies are telling us. We could deeply reduce carbon dioxide emissions by taking similar steps on methane and nitrous oxide and fertilizer use and landfills, and in other areas, turn that curve of greenhouse gas emissions sharply lower. Help keep the planet below the two degree centigrade rise. It’s possible, but time is running out. So let’s look at how we can accelerate progress.

Consequences of Climatic Change

Why should we care about human-induced climate change? The fact of the matter is, we should be scared, truly scared. Not so frightened that we’re paralyzed, but rather scared into action because the consequences on a business-as-usual trajectory for this planet could absolutely be dire. We are on a path of putting so much carbon dioxide, methane, nitrous oxide into the atmosphere that the temperature increase on average on the planet could be several degrees centigrade by the end of this century. Four, five, six, eight, nine degrees centigrade, there’s no absolute precision on how big the increase could be because we can’t really say, first of all, how much greenhouse gas we will be putting in, even in a growing world economy on a business-as-usual path. And there are also undoubted uncertainties about the Earth’s processes. And our climate models do not have the precision to be able to get down to the decimal point of the likely increases of temperature. But, because we have so much evidence coming from so many different directions, the Paleoclimate, the statistical models used by climate scientists, the evidence of what’s already happening around the world, we can be pretty sure that the consequences could be very, very dire indeed unless we change course. One very useful way to view this was presented in an important report on climate change produced by Lord Stern in the United Kingdom a few years ago. And the Stern review of climate change included the picture that you’re looking at now. Now, you see across the horizontal axis, zero degrees centigrade, one degree, two degrees, three degrees, four degrees, five degrees centigrade. This is showing all of the possibilities for the increase of temperatures during the twenty-first century depending on how much greenhouse gas we end up emitting and how the Earth’s systems respond to that. Down the side axis, we have the kinds of consequences that we should expect for different temperatures. There will be consequences for the food supply. There will be consequences for water. There will be consequences for the functioning of ecosystems and the survival of other species. There will be consequences for extreme weather events such as droughts, floods, mega heat waves, mega storms, big cyclones, typhoons, hurricanes. There will be consequences and risks of very rapid, dramatic changes to key Earth systems that could cause the climate, not only to change as markedly as shown here, but even more markedly through sudden alterations of the Earth’s climate system. What this graph shows is that for any of these categories, sey food, as you look at the consequences at one degree centigrade, compare them with the consequences at two degrees centigrade. Compare them at, for the consequences that would occur at an increase of five degrees centigrade. The more change there is in the average temperature caused by bigger increases of greenhouse gasses, the bigger risks we face. If we can head off a, a lot of the greenhouse gas emissions by shifting from fossil fuels to other kinds of energy, for example, then the consequences will be smaller because the temperature increases will be smaller. If, instead, we continue just going right along our merry way with increasing oil, gas, coal, and other greenhouse gases, and so we have a big increase of temperature, the consequences could be completely disastrous. Consider food, for example. At one degree centigrade, one of the consequences is severe impacts in the Sahel region. The Sahel, remember, is the part of West Africa just below the Sahara Desert. Mali, Niger, Chad, it’s a dry region, could get dryer. The consequences for the Sahel, even at a one degree increase, which we basically already had, are quite serious. What would happen at five degrees centigrade increase? Well, according to the evidence, entire regions would experience major declines in crop yields, up to one third decline of crop yields in Africa, for example. That would be tantamount to mass hunger, even starvation in parts of the world. If we just let things rip, and the temperatures, therefore, rise by four or five degrees centigrade so that we’re at the extreme danger end of this graph, then the consequences are absolutely terrifying. With water at one degree centigrade you see that small mountain glaciers are disappearing. And this will cause threats to the water supply in places that depend on glacier melt for their water in the rivers. But go over to five degrees centigrade, and you see that sea level rise would threaten major world cities including London, Shanghai, New York, Tokyo and Hong Kong. Calamitous events possible with a mega rise in sea levels even of several meters, possibly, if the big ice sheets in West Antarctica and in Greenland melt sufficiently or break up in ways that cause a mega rise in sea level. And the Earth’s history tells us absolutely possible because in earlier episodes of high CO2 concentrations in the Earth’s paleohistory, the old climate, the sea level was often many, many meters higher than it is on the planet today because much less ice was trapped in the ice sheets of Antarctica and Greenland and, instead, was filling the ocean basin and raising the sea level. Well, as we’ve talked about many, many times, we’ve built our big cities right on the coast. That’s where the economy is best, where trade is best, where productivity is high. And yet, those are the cities under incredible peril. Well, in case after case, if we just let her rip, the dangers for our ability to feed the planet, our ability for our cities to remain safe from extreme hazards, our abilities to maintain public health, our abilities to avoid other calamitous dramatic change of earth’s processes, for instance changes in, in the ocean circulation or irreversible disintegration of parts of the ice sheets is called into real threat. We know that certain regions of the world are extraordinarily vulnerable like the Sahel that you’re looking at here where it is already prone to massive, droughts and where the populations are already very poor. We’re seeing those dangers, not as potential threats of the future, but as already clear and present dangers, because the Sahel has lived through serious droughts in recent years with very serious consequences for loss of life and for the onset of conflict. The Mediterranean Basin, which includes the countries of southern Europe Spain Italy, Greece, Yugoslavia, and the countries of North Africa Morocco, Algeria, Libya, Tunisia, Egypt and the eastern Mediterranean, this is a region where the climate science tells us that a relatively dry region that produces some of the, the world’s most beloved products, whether it’s the olive oils or the great wines of this region, could be devastated by drying. And so, these are three of many regions that have been identified as facing profound threats. Mm, and this is not simply in the imagination of the climatologists or, or even in the traces of their mathematical models. This is what we’re already observing even with the limited human-induced climate change that we’ve experienced now, which could be a small fraction of what’s to come. Have a look at the changes of of, of rainfall experienced in the Mediterranean Basin over the last century. The whole Mediterranean Basin has experienced a significant trend of drying. And the record shows if we continue with business as usual, that it could experience further dramatic drying with quite devastating consequences to the economies, to the nature, to the ecosystems, to food security even in this region. The evidence from the mathematical models is that the trends that we’ve been experiencing till now, for example, the drying in the Sahel or the drying in the Mediterranean, foreshadow what would happen if we continue as we’re going, but with consequences far more severe than what we’ve seen to date. You’re looking now at a map recently produced by a climate science group that studies the propensity to drought on the planet. And the map that you’re looking at shows you in the red areas, places likely to experience significant declines of rainfall and significant increases of drought intensity and frequency. It’s an ugly picture because you see red everywhere. A tremendous amount of the world’s areas would likely experience significant declines of soil moisture that they need to grow food and would experience a significant increase of intensity of drought at the same time. Now we know that another consequence that could be devastating is the rise of sea levels as ice sheets melt or just break apart pushing ice or water into the open ocean and raising sea levels. In the northeast of the United States where I live, the estimate is that, over the last century, the sea level has already increased by about one foot or one third of a meter. I, you might think that we’d get a uniform rise of sea level in all parts of the world, but topography and other geologic features mean that the rise of sea levels will differ in differ, different parts of the world. A one foot increase, what has already been experienced, played a major role in the havoc of the massive floods that hit New York City, that we’ve already looked at, and the whole Eastern Seaboard during superstorm Sandy. Storm surges eh, coastal erosion are already occurring as sea levels are rising. But the new evidence suggests that by the end of the century on a business-as-usual path, sea levels could be a meter higher than they are right now, three or four feet higher. And if the worst case happened, which is a catastrophic loss of part of the West Antarctic ice sheet, for example, the rise of sea level could even be several meters. You put this together. The consequences for urban areas, hugging the oceans, for our food supplies around the world are, are absolutely extraordinary, potentially devastating. The map that you’re looking at now attempts to ask what would happen to food production if this combination of warmer temperatures and more drying were to take place. And what you see here is South Asia and tropical Africa in the absolute red zones, or red and pink zones meaning major loss of agricultural production, so too the Southern part of the United States and much of Latin America, much of Australia. What are we doing? We’re putting the world’s food supplies at great risk. And again, it’s not hypothetical because we’ve already had a serious derangement of production in many places in the world as droughts have hit in recent years and as higher temperatures have undermined crop yield, sometimes killing crops or dramatically reducing the crop yields. A final point that I would like to stress is that, even if one put aside all of the climate-induced changes coming from this human-induced rise of carbon dioxide concentrations, all of the major storm events, the rising sea levels, the rising temperatures the increased floods and droughts, the loss of soil moisture needed to grow food, it’s a big, long, very threatening list. Put all of that aside. The basic physical fact that a higher CO2 concentration in the atmosphere will lead to more carbon dioxide dissolving in the oceans causing acidity in the ocean, by itself is frightening enough because, as I’ve discussed, as the oceans become more acidic, and there’s a lot more acidification on the way, major parts of the marine ecosystems, the shellfish, the animals with exoskeletons, the plankton with the calcareous exteriors, but part of the major food chains in the world, the Coral Reefs, which are so vital for the marine ecosystems, could experience, and are likely to experience, a massive dying. We’re playing with threats beyond our easy imagination. We’re in a kind of denial that is added to by, unfortunately, propaganda by major vested interest groups, like big oil companies.  We are playing with the survival of millions of other species, adding to this tremendous risk of the sixth great extinction on the planet that we’ve looked at before; the other five caused by nature itself, this one by humanity in it’s thoughtlessness if we continue on this course. We can see that we have every reason to change the game, every reason to play for a control of these forces, every reason to mitigate the human-induced climate change for our own safety, for the safety of the planet, and for future generations. How can these forces be reduced? How can we mitigate human-induced climate change? That’s our next topic.

The Basic Science of Climate Change

Climate change is the biggest of all the environmental threats that we face, and the magnitude of this threat is only gradually dawning on humanity. It is, in my view, the very toughest of public policy problems that humanity on a whole has ever faced. Let me mention why[1]. First it’s global, many problems are local, local communities can solve them. So problems are national, this one involves the entire world. The problem goes to the core of the economy. Our economy runs on energy. And energy in the form of fossil fuels is both the driver of the world economy, and the essence of the climate change problem. Because when we burn fossil fuels, we emit carbon dioxide into the atmosphere. And that is the major reason why humanity is changing the climate. Not the only one, but the major one. Third, this is a dire problem. The consequences and the stakes are absolutely huge. Sometimes problems are difficult, but they don’t matter all that much. This one matters a lot. Next it’s slow moving. We’re just not good enough to see it day by day, year by year, what’s really happening to the planet. The scientists are telling us, watch out, you’re getting to the cliff, you’re hitting the thresholds, you’re crossing the boundaries of safety, but life goes on. And because this is a problem that stretches out over decades the politicians, the businesses and all of us don’t necessarily feel lit and know it and realize the dangers of it. Because it’s slowly, slowly creeping up on us. Not slow by the chronology of the planet because events are changing very fast by that standard but a little bit slow by news events and that’s part of what confuses us. It’s a complicated problem because it involves many parts of the world economy and involves every part of the world both in the impacts of climate change on humanity, but also on the causes of climate change. Because every part of the world is contributing to the problem, though some places, like the United States, on a per person basis are contributing hugely relative to other places, which are mainly victims, especially the poorest parts of the world that still don’t use very much fossil fuel energy. This is a multi-generational problem. A lot of the impact will be felt by people not even born yet, they’re obviously not voting. They’re not able to raise their voice, and yet the impacts on them will be absolutely huge. And finally, this is an issue on which there are very powerful lobbies. None more powerful than big oil. The oil industry is a rich industry. Massive flows of revenues and profits.And that that can be used for media, that can be used to confuse the public to defend the status quo, to fund politicians that are going to continue to look after the interests of the fossil fuel industry even when that interest may be so dangerous for the planet. So we have a lot of vested politics in this issue as well. Well in order to see really what needs to be done and how it might be done, we have to start with the science. And the science I think it’s important to state it’s not some new fangled, invention of, of the latest, scientific publication. The basics of how greenhouse gases warm the planet and what humanity might do, therefore, to the Earth’s average temperature as a result of the increase of greenhouse gases has been known for more than 100 years. You’d never know that from climate skeptics and the climate change deniers, but the fact of the matter is that the first serious, absolutely brilliant scientific study of what would happen if the amount of carbon dioxide, CO2, in the atmosphere were to double, how temperature would, would change was published in 1896 by Gustavus Arrhenius, an absolutely brilliant Nobel Laureate chemist in Sweden who worked out by paper and pencil, and did it just right. What would happen if CO2 were to double? He got the answer right, that the temperature on the planet would rise by a few degrees centigrade. He didn’t get the timescale right, because he said that while human use of coal and oil and other fossil fuels would eventually double carbon dioxide, he thought that would take hundreds and hundreds of years, maybe 700 or 800 years. But in fact, because of the geometric growth of the world economy, a process that looked like it might take hundreds and hundreds of years could happen within roughly 150 years from the time that Eranius wrote, by the middle of the 21st century, by 2050 or so. That’s a very frightening prospect. Why is it frightening? Well, the basic reason is shown in this schematic diagram of the greenhouse gas effect. What it shows is that sunshine coming from the sun reaches the planet as ultraviolet radiation. A little bit of it is reflected by the clouds. Most of it reaches the earth. A little bit of that is reflected by the ice and other land surfaces on the planet but most of it is absorbed by the earth. The Earth warms and as a result of it’s warming, the Earth radiates infrared radiation back into space. The Earth warms enough so that the outgoing infrared radiation equals the incoming ultraviolet radiation. That’s a thermal balance, or thermal equilibrium. Now you put a level of greenhouse gasses into the atmosphere. Carbon dioxide, methane, nitrous oxide and others. Those molecules have a particular property that they absorb some of the infrared radiation and trap it and warm the planet more than the planet would be warmed if those greenhouse gases didn’t exist. Indeed, if we had no greenhouse gasses the temperature of Earth would be something like the temperature of the moon. A lot colder and unable to support life as we know it. It’s because of this envelope of greenhouse gasses that Earth is indeed warmer. So far, so good. But now if humanity increases the amount of the greenhouse gases in the atmosphere, then we create problems. Because life on the planet, and humanity, and our civilization, have evolved in a certain kind of climate, but now we’re changing the climate by adding more molecules of greenhouse gasses in the atmosphere, warming the climate and pushing the thermal equilibrium to higher temperatures that threaten us in a variety of ways. There are several chemical compounds or molecules that have this property that they trap infrared radiation. Carbon Dioxide is the most important of these; nitrous oxide, methane, and some industrial chemicals. The total warming effect sometimes called the total radiative forcing of the greenhouse gases, is the sum of the effects of each of these greenhouse gases. The total radiative forcing caused by human activity that is caused by the emissions of CO2, methane, nitrous oxide and these industrial chemicals leads to the overall warming effect and of that, carbon dioxide accounts for about 77% or about three quarters of the total effect. Methane is the second most important of the human induced greenhouse gases. And nitrous oxide is the third and the sum of the radiative forcings of those three types of greenhouse gases account for about 99% of the total greenhouse effect. In magnitude, we’ve been emitting more and more of those gases over time. The measurement of the total emissions is in what’s called giga-tons, meaning billions of tons of carbon dioxide equivalent. We ask how much warming is caused by the sum of all of these greenhouse gases, and we ask what would be the equivalent amount of just carbon dioxide be. And that’s called CO2 e, or carbon dioxide equivalent tons of emission each year. And to give you the round numbers we’re emitting right now on the order of about 55 billion tons of carbon dioxide equivalent per year. The carbon dioxide part of that total is about 35 billion tons of carbon dioxide. Most of that is coming from burning coal, oil and gas a much smaller part of that, around 10% is coming from cutting down trees. Cutting down the rainforest and there by releasing carbon dioxide from the trees back into the atmosphere. Well, how big is this effect? It’s big enough to cause us really huge dangers. About 50 years ago, a very far-sighted scientist put some monitors a, on a mountaintop in Hawaii, and he started measuring the amount of carbon dioxide in the atmosphere. And thanks to those measurements from 1958 till now, we have annual and actually even within the year fluctuations of carbon dioxide levels from then until now. And this is known among earth scientists as the Keeling Curve because it was Dr. Keeling who put up the monitor, and what the Keeling Curve shows is that the amount of carbon dioxide in the atmosphere has been rising significantly. Measured as parts per million of carbon dioxide, the number of CO2 molecules per million of total molecules in the air, most of which is nitrogen part of which is oxygen, and then just a bit of carbon dioxide. But that little bit is enough to change the whole climate. Starting back in 1958 when that machine first went to, up on the top of Mauna Loa in Hawaii, the carbon dioxide was 320 molecules for every one million molecules in the air, or we say 320 parts per million. By now, CO2 has reached 400 parts per million. Before James Watt came with his brilliant steam engine, the atmosphere contained about 280 parts per million. In the geologic history of the last three million years, the CO2 varied roughly between 150 and 300 parts per million. Then came humanity, and we’ve been burning so much oil, gas, and coal, that we’ve now sent the CO2 levels absolutely soaring. And reaching the 400 parts per million level in the spring of 2013. A concentration of carbon dioxide not seen on the planet for three million years. In other words, human activity is pushing the planet into a climate zone completely unknown in human history, and unknown in the Earth’s recent history. Some of the great scientists, many of, of my colleagues I’m honored to say, like Professor James Hanson, are able to use various techniques to look at the long history of carbon dioxide and temperatures on the planet Earth. And the picture you’re looking at now is a, a, a kind of manuscript of the Earth’s history showing a long record over the past 400,000 years of fluctuations in carbon dioxide and in temperature on the planet. Now these fluctuations in carbon dioxide were not caused by humanity using a steam engine obviously, this is hundreds of thousands of years ago. These were natural fluctuations of carbon dioxide driven by natural processes. By volcanoes, by the re-absorption of carbon dioxide into the oceans. And by changes of the Earth’s orbital cycle on a periodicity of tens of thousands of years. But what the paleoclimate record shows is that when CO2 is high, temperatures are high. And this is the basic greenhouse effect. Raise the CO2 in the atmosphere, expect a warmer planet. This has been true throughout history. And it is true now. We have been in a process of raising the carbon dioxide level and the other greenhouse gases. Nitrous oxide, methane and the industrial chemicals that the, floor carbons and so forth, the HFCs and the others. And by doing so we have led to a warming of the planet within modern history. If you look to the temperature at the start of the industrial revolution until now. The Earth has warmed by about 8 10ths of one degree centigrade. Because there’s more greenhouse gas in the atmosphere. And the Earth hasn’t yet finished its warming in response to the greenhouse gas increases that humanity has caused. Even if we were to put no more greenhouse gases into the atmosphere, but just to stay with what’s there right now, Earth would continue to warm by perhaps another 0.6 of one degree centigrade. Because the oceans large bath tubs take a long time to warm up in response to the greenhouse gases. So we’ve seen perhaps half or a little bit more than half of the warming that will come from the carbon dioxide and other greenhouse gases already put in the air. But we’re not done, we’ve been accelerating the amount of greenhouse gases that we’re putting into the air, we’re increasing the amount of methane, increasing the amount of nitrous oxide. The fact of the matter is, that even though in more than 20 years since the world’s governments said, we have an urgent challenge of heading off the human induced greenhouse gases in order to prevent a huge dangerous change of the Earth’s climate. 20 years on, we’ve still not turned the needle of slowing down our emissions, much less stopping them. The rate of emissions has been going up year to year as the world economy has been increasing in scale. And with the growth of China, we’ve seen an enormous increase of greenhouse gas emissions in recent years. Because China by itself by virtue of its huge size and by virtue of its use of coal as its primary energy source has become the world’s largest emitter of carbon dioxide. We’re on a dangerous path. Let’s now understand, what are the dangers of this rise of temperature. And of other changes of the climate system. What does it mean for us? Why should we worry?

[1] http://www.ncdc.noaa.gov/cag/time-series/global, https://yearbook.enerdata.net/,