Climate Change: Science, Policy and Risks
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NobeliumChemistryHondurasSense DistrictChemistryLecture/Conference
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NobeliumComputer animation
Transcript: English(auto-generated)
00:21
Thank you very much. Just to get started, I will talk about climate change. We just heard some talks in physics and before that chemistry. Well, climate change has some
00:41
chemistry in it, but I will be talking more about the science policy and risks perspective. We already heard the talk by Steve Hsu presented by William Murner. So my presentation will be complementary. There will be just a few things that will be repeated, but in a very general sense,
01:05
it will be complementary. I've known Steve Hsu and I've worked with him for many years now, so we are good friends. So I just regret that he was not able to be here. So what I'm going to do to stress again the science policy issues is
01:26
let me talk about some of the myths that are connected with climate change. Climate change, we understand, we have heard it already several times, is one of the most pressing, if not the most pressing problem that society has at the moment, certainly the most pressing environmental
01:47
problems. But there is a very common view that is expressed in the media and by many people leave it that climate change is natural, climate has always changed in the past,
02:03
so it really has no connection with human activities. Well, it turns out that there have been some very careful surveys of the literature, the scientific literature, followed by personal surveys and so on, that really demonstrate that there is an unusual
02:26
situation. It doesn't always happen in science, but there is this consensus among scientists, more than 97% according to some of these reviews that are now several years old. Certainly agree that climate change and that it is most likely caused by human activities.
02:49
There are of course always some scientists that disagree, here we have 3%. It turns out we know these scientists very well and so we know their arguments, they have been tested, explored
03:04
and certainly do not convince the rest of the 97%. But there is something else interesting happening, which is we're talking here about not just scientists but climate change scientists.
03:20
In general, scientists are skeptical, so they question things, that's okay, that's the way science works. So one, I'm just going to show you an example of this attitude of scientists that are not necessarily climate scientists. Namely, there was an op-ed in the Wall Street Journal
03:43
that, as you know, is fairly conservative, some years ago claiming that, well, that many of us were really exaggerating, that it is not really true that something dramatic
04:00
needs to be done and so on. And a large number of distinguished scientists do not agree with this. It turns out that subsequent to this there was also a massive sort of survey, but that included many artists, many non-scientists. But anyhow, in this particular case it turns
04:24
out that most of these 16 scientists were not connected to climate science. So fortunately the Wall Street Journal did agree to publish a response and as you can see the way this is labeled, well, if you have a heart attack or you have a problem with your heart, you
04:44
don't go to see your dentist. You normally go to see the experts. So what is very clear, seems to be very clear now, is most people, including scientists that talk about climate change in the fashion I showed here, really know practically nothing about the
05:07
science of climate change. So what I want to do next is just review historically this climate change science. I want to deal very much with the science itself, but I just
05:20
want to review a few facts to remind you that probably all of you know. First of all, just a view of our planet, just to show the atmosphere. But the atmosphere is very thin. You cannot really see it. It's like the skin of an apple. But that's what
05:40
determines the climate of our system. And just one point to indicate while I have this photograph is that, to indicate here, if you emit something to the atmosphere, say a gas, that is relatively long-lived, some gases survive just a few hours, and some particles
06:04
perhaps can survive a few weeks, but there are some gases that remain there longer. But if you emit something, say here in the northern hemisphere, the winds work in such a way that within a few months, that substance is mixed throughout the northern
06:24
hemisphere. It takes a little longer to mix in the southern hemisphere because there's a mixing barrier, but it takes roughly a year and a half, less than two years, for this mixing to take place. And this is what gives rise to what we call global problems. Because when we're talking about emissions of the species,
06:46
gases that last more than a few months, more than a few years, it doesn't matter where they are emitted on the planet. They are really giving rise truly to global problems. One such problem is the stratospheric ozone issue, which is not what I've discussed here,
07:04
but we work with Paul. If I have time, I'll mention a few things about it more towards the very end. But the other important global issue is, of course, climate change. Now, historically, the idea is the following. How did scientists first assess what should be
07:26
the climate of our planet? And this really started with Joseph Fourier, a very well-known mathematician, who first sort of figured out, yeah, the Earth receives energy from the sun. So that's really what should determine what should be our climate. And he was already talking
07:49
about non-luminous heat, electromagnetic radiation that we cannot see. And he connected that with the expected temperature of the Earth. The next sort of important finding there was from
08:04
Jontinda, which is that there are certain gases in the atmosphere that they are transparent to the energy from the sun, but they actually absorb a part of the electromagnetic radiation. He was able to identify very clearly
08:25
water and carbon dioxide as the two main components of these sort of additional species that are transparent to visible, but not transparent to infrared radiation. But the third important
08:41
scientist here, Svante Arrhenius, and of course, for those of you that are chemists, we know that Arrhenius made several important discoveries there. For me, as a gas kineticist, the Arrhenius equation that describes how fast chemical reactions proceed. But also, he received the Nobel Prize. It was actually for his discovery that something like
09:05
salt, sodium chloride in water gives ions, sodium ions, chloride ions, and so on. But he also worried about climate change. And what he did is with the knowledge I just described, he was able to do calculations, very tedious calculations, predicting that if humans were
09:20
to continue to generate carbon dioxide, the temperature of the planet might rise by this century, perhaps even something like four or more degrees. And that's remarkable, considering that he did that at the beginning of the 20th century, it is remarkably accurate.
09:46
Well, let me explain now a little bit in more detail how does this come about. This is some basic science. This is something we teach to even high school students and so on.
10:04
Here is the idea. Of course, the Earth receives electromagnetic radiation mostly in the form of visible energy. But we know that this energy is also lost to space. And that's what was
10:21
discussed in the early days. I should have mentioned when talking about Fourier that at that time, there was the idea that heat itself was some sort of fluid, phlogiston or caloric, and that this heat somehow or all this fluid was transmitted from
10:41
one body to another and so on and so forth. So it took a while for thermodynamics to really become a science. And it is really the first law of thermodynamics that is very important in establishing this idea what determines the climate of our planet.
11:03
And the idea is the following. Energy is conserved. That means if the Earth receives a lot of energy and if it reaches equilibrium, which is something that it has done millions
11:21
of years ago. Equilibrium is a state of a situation in which the physical properties no longer change with time. I am, of course, oversimplifying here. But for our planet many millions of years ago, the amount of energy that it receives equals the amount of energy that it
11:43
loses. This is in contrast to what people normally think that, say, when you put a mantle on your body, it traps the heat so it doesn't allow energy to flow anymore. Of course, we know that after a while the amount of heat generated by your body is lost to space. And that happens
12:03
with our planet as well. The amount of energy received equals the amount of energy lost, but because the Earth is at a much lower temperature, it loses the energy in the form of infrared radiation. And this came out of experiments, the so-called black body radiation
12:22
experiments, where you could measure in the laboratory this amount of energy lost by any particular body in a laboratory, which depends only on its temperature. But it was an empirical law.
12:42
But considering that particular law, which was just experimentally determined, and considering the fact that you could measure the amount of energy going from the Sun, you would determine that the average surface temperature of our planet should be about minus 18 degrees Celsius
13:04
or degrees centigrade. And if that were to be correct, we wouldn't be here, because the planet would be frozen. Well, here is what happened. This black body radiation law, which was for some time not understood where it came from, but it was of course the
13:26
Max Planck that then interpreted this black body radiation law. That's what gave rise to quantum mechanics. By suggesting something which at the beginning of the 20th century was sort of not quite reasonable, that energy comes in packets. So anyhow, that's the origin of quantum
13:47
mechanics, has to do with that description. Einstein himself also provided a very important component, not only that the energy comes in packets, but also radiation. Photons, okay, they are quantized. And that's why the temperature, it's very sensitive to the
14:07
temperature. Now, this gives rise to what we call the natural greenhouse effect, which is the following. If our planet had just a transparent atmosphere, it received, say,
14:26
a hundred in some units of energy from the Sun. About one third is reflected to space, but the rest is emitted by the surface, and that's what would keep the temperature at minus 18.
14:41
But what really happens is that the atmosphere is not transparent. It's like a blanket. The atmosphere has a blanket, and that's what means that the temperature has to rise at the surface. It has to emit a lot more energy because a good fraction of that energy is not lost to space. It comes back to the surface. I won't go into the details, but of course,
15:03
that's oversimplified. There have been all sorts of measurements, and the overall energy balance is a bit more complicated, but it's very well understood. This is fundamental science. And one more piece of information is that basically it's only a small fraction of the atmosphere
15:25
that gives rise to this natural greenhouse effect, a lot less than one percent. Water vapor was understood to be the most important so-called greenhouse gas because of this natural greenhouse effect, absorbing about three-fourths of this infrared energy we're talking about,
15:45
and carbon dioxide the other fourth. So from that perspective, one would think water vapor is what controls temperature. But as you know, water vapor, the amount in the atmosphere depends critically on temperature. So what I have here is just to give you a sense,
16:01
particularly not to you people that work with science, but the public in general that are not very familiar with gases, the amount of water vapor, if we were to condense it typically, what is in the atmosphere, would occupy just a few centimeters, and the amount of carbon dioxide, if it were to be solid, say just four millimeters, that's the blanket that our planet
16:25
has. A very small blanket, if you want, that raises the temperature of these 33 degrees for the natural greenhouse effect. But if we were to remove carbon dioxide, the water would condense, and then we would have a frozen planet. So that's why carbon dioxide is called
16:45
the thermostat of the planet. And what's happened to carbon dioxide? This you already heard from Steve Chu's presentation. I could go back millions of years, but in more
17:01
recent years, 10,000 years, what you see is how suddenly, in very recent times, the concentration has increased quite dramatically. And it's very clear that this comes from burning fossil fuels, you can do isotope analysis, things like that. It's also quite clear that the temperature on the same time scale has abnormally changed just in recent times.
17:26
So the question, the obvious question is where does this come from, and the best explanation is this has to do with the greenhouse effect. But in any event, the scientific community gets together and every few years this
17:44
intergovernmental panel on climate change makes statements about what is the status of the science. And the last big report was a few years ago. And the conclusion in the previous report is that yes, this temperature change is indeed connected to the carbon dioxide
18:02
change, but we're not absolutely sure of the connection. So we talk about probabilities. At that time it was 90%, but in the last report they raised it to 95%. So it's possible that this natural is just extremely unlikely. But let's move on with the myths. I want to
18:22
get to several additional points. One other myth is why worry about this? Let our children, grandchildren take care of the problem because this will happen towards the end of the century when more carbon dioxide will pile up. But that's not really the case. What we know is that, for example, the Arctic Sea in the summer is melting, as you can see
18:45
from these pictures. This is something very dramatic that has happened particularly in recent times. But more worrisome perhaps is what we call extreme weather events. This doesn't represent a relatively small change in temperature that we have seen. I should have
19:02
quantified that it's of the order of just one degree centigrade. But we have extreme weather events, heatwaves, floods, and so on, that have increased in recent times, storms, landslides, and so on. And the scientific community was very sort of careful.
19:23
And until some years ago they thought they didn't have enough statistics to make any connection. But in recent years it's very clear now that the connection is statistical. Climate change doesn't cause these extreme events, but it certainly increases their intensity. And that's why this is what I'm stating. These scientists were very skeptical.
19:45
But the conclusion is that, yes, these events are indeed affected by climate change. For example, the Hurricane Sandy that was so expensive in the United States, it is most likely influenced
20:01
then by climate change. But let's now move on to the last of the myths I have here. And this is no longer science. This is economics. We shouldn't do anything about climate change because fossil fuels are so important for the functioning of society that we just shouldn't
20:27
risk doing anything about this. Well, that turns out to be also a myth. And some years ago, it was already indicated by our colleagues at Princeton that the way to solve the climate
20:42
change problem, there's no silver bullet, there's no simple big solution that you can do. So if we have emissions here as a function of time, what you need to do is many things simultaneously, so-called wedges. You have to improve the fuel economy, the efficiency with
21:02
which you use particularly fossil fuel, more efficient buildings and so on. But you have to start using renewable energies. Even nuclear energy, that's of course questionable, that gives rise to a different debate. But wind and solar are particularly important as we see here.
21:25
But what is very dramatic about these particular energy forms now, renewable energy forms, as you already heard in Steve Chu's presentations, is that the price has come down quite fast.
21:41
So it turns out that in recent years, these types of energies are quite competitive now with fossil fuels. They still have problems with storage and so on. But that's coming along now. It's moving. And so if we see reports from economists, perhaps one of the most famous,
22:04
one is from Lord Nicholas-Turne, from some years ago where he stated already a decade ago or something that it would only take about 1% of global GDP to make the necessary changes so that we wouldn't have to risk this huge
22:27
temperature rise that might occur otherwise. Anyhow, that was quite well substantiated. But what is quite interesting is in much more recent reports, in order for society to decide whether to do it or not, it's not only how much does it cost,
22:44
but how much does it cost not to do it. So that's how society should function. Science doesn't tell you what to do. Science is neither good nor bad. So science just provides the facts. It can make predictions. What would happen if you do this, if you do that? And
23:05
that's why the Intergovernmental Panel on Climate Change is supposed to be nonpolitical. It just states the facts, what the scientific community thinks. But you mix then the science with economics and with social and political aspects, and that's how you take decisions. And that's where ethical
23:25
principles are very important, which I'll mention more in just a moment. But the point is that the damage that would be caused by climate change in general have been grossly underestimated. This is what is very worrisome. So if, in principle, what would need to happen
23:44
to control climate change? I won't go into this in too detail, but ideally from an economist's perspective, you put a price on emissions. But this has not been practical. There was a meeting of this Intergovernmental Panel on Climate Change already in 2009, where about 150 heads of state
24:08
were there, and they agreed, let's change things so that the temperature doesn't increase more than two degrees. But the negotiators didn't agree. The heads of state did. So it took a bit longer. It took some more time until 2015, December of 2015. Finally, an international
24:31
agreement was reached, the so-called Paris Agreement, in which practically all the countries of the planet together agreed that indeed, let's try and see whether we can keep the temperature
24:44
rise below two degrees. And the way we will do it is in contrast to the earlier attempts, where, for example, the Kyoto Protocol, the first attempts, they were assuming that only developed countries, which were the ones that originally caused the
25:07
problem, would do something, and then developing countries would wait until things would stabilize a bit more. That didn't work. That was not a practical way to do it. So the big change in the Paris Agreement is practically all the countries, including China, developing countries,
25:22
India, Mexico, and so on, would commit themselves to do something on a voluntary basis. However, something that could be measured, that could be demonstrated, and so it was a very big achievement. And here is, if I put emissions versus time, we can see that the Paris Accord
25:48
doesn't reach the two degrees. It goes well above that, because it's just a first step. The idea is that all the nations will collaborate, will work together, and they will try to strengthen the Paris Agreement itself. But as such, it's not sufficient. I should also mention
26:10
here why was, what's the nature of the Paris Accord? I've been advising the President of Mexico, but I was also a member of PCAST, which is the advisory group, about 20 scientists,
26:25
the scientific advisory group, to President Obama. So we worked closely with him on the Paris Accord, and it was essentially designed by the limits that the United States had to place,
26:41
namely to do something that would not require the approval of Congress, because the Congress in the United States, as you know, is led by Republicans who question the nature of climate change. And so this is, let me just spend a few minutes very rapidly
27:01
talking about this. It turns out that it's well established already for some time now that it was industrial groups that put in question the signs of climate change. But those groups where the people that were managing those groups are exactly the same. Those are the same people
27:27
that delayed governments to do something about smoking and about several other interventions. They were just representing industry. But what's happened more recently is not just that there are industrial perspectives, economic perspectives, but it became, climate change became politicized.
27:46
And so it was a mantra of the Republican Party in the United States, just to, not to believe in climate change signs and to mention that it was all just a hoax in some sense, that it is not something real. So I have just a couple of minutes.
28:07
I need to mention what has happened recently, namely, as you know, the United States, through President Trump, did not agree with, they decided not to accept the Paris Agreement.
28:21
But let me go back in time, just in times of the election. This was just typical of anybody belonging to the Republican Party in the United States. And why do I mention the United States? Because it's crucial for this international agreement. But as you see, the idea is that this is the climate change issue, something that is not believable. That's very worrisome for us,
28:45
the scientific community, because as I mentioned, it's very well established. It's basic science and so on. So we're living in a world where very important politicians question that. There are always people questioning many aspects of science, as we know.
29:01
I could give lots of examples with vaccines and so on. But the worry here is that it's President of the United States that is making such incredible statements. Well, let me just move on. I mentioned this because there were lots and lots of pieces in the media criticizing, of course, Trump's decision. A few of them, as expected,
29:24
would agree with what the United States decided, namely not to accept the Paris Agreement. I won't go into the details, except that most of the scientific organizations, practically all of them, made strong statements strongly disagreeing with President Trump's perspective.
29:49
But what I want to highlight that was not very much highlighted in the news is something that, for example, Jeffrey Sachs mentioned that global warming is an existential threat. It's a big worry for the following. So I want to spend probably one extra minute.
30:06
I was a professor at MIT for many years. So there it was acknowledged because the climate is a complex system. You cannot predict with certainty what will be the temperature change in the future for any particular scenario. So they had these two spinning wheels. The one in the
30:25
left with red is if you do business as usual, which is what President Trump and his team would argue. But you can actually change that if you have reductions in the emissions.
30:40
The big problem is that there are some red portions there in these flags. And the same thing, the same results were actually projected by the International Panel on Climate Change. Namely, the red part here is what happens if you do the business as usual scenario, if you don't worry about climate change, if you think that indeed it's a hoax and so on.
31:03
And here is what is most worrisome. Here is how the scientific community would try to summarize this. It's not necessarily what's the most likely change if we do nothing. That might be three or four degrees. But we look at what we call the, economists are worried a lot about this,
31:23
which is just the tails of the distributions. And the summary situation is then the following. There is a probability of roughly one in five that the temperature will increase more than five, five or six degrees towards the end of the century. If that were to be the case,
31:45
that is a very highly irresponsible act, namely to allow that probability to go on for future generations because it really doesn't respect the rights of future generations.
32:00
It's an ethical issue, highly, highly irresponsible because if the temperature was more than five degrees, you could have all sorts of extreme events. For example, parts of the planet would be uninhabitable. There would be all sorts of food production problem, mass migrations, wars and so on and so forth. So that's my summary, that it's extremely irresponsible
32:27
and irrational. It's extraordinarily irrational, the attitude that the US president has taken. So let me just finish with mentioning very briefly that we fortunately have one example
32:42
of a global issue that has been solved. Paul Crutzen here has been instrumental with that, and that's the depletion of the ozone layer. And without this international agreement, which is a Montreal Protocol, we would be in very big trouble today. But fortunately, all the countries in the planet practically accepted the agreement. And so with the protocol,
33:05
we know that the ozone layer is finally recovering. So we know it can be done. We can all work together and avoid these extreme irresponsibilities. Thank you for your attention.
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