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Welcome to Cambridge forum discussing global climate change. I'm Tim Weiss cola member of the formis board. The December 2000 9 Copenhagen talks on Global Climate Change failed to produce a new international accord limiting greenhouse gas emissions and more and more scientists and citizens are realizing that whether or not the international community is able to establish a plan to mitigate the rise in greenhouse gases. Current levels of carbon dioxide and the course of industrialization in developing countries point to the need to consider the impacts of climate change and make plans for adapting not just mitigating but adapting to its effects. But are scientists learning about the effects of warming. What problems will these effects pose for the populations of the United States and around the world. What should citizens scientists and governments be doing to prevent
the worst effects of climate change. What we saw in Copenhagen was a kind of uniting of citizens and scientists and the governments are lagged behind. But to lead us in our deliberations today we have a number of scientists and we're starting off with Dr. Ronald Penn who is the TEPCO professor of atmospheric chemistry at MIT's department of Earth Atmospheric and Planetary Science one of his projects has been measuring the rates of change in atmospheric concentrations of trace greenhouse gases for more than 30 years. We're used to talking about CO2 buildup but there's a whole range of other gases that we should be paying attention to. Recently he and his colleagues noted an unexplained increase in methane concentrations which led them to reconsider the impact of methane BS of the climate change as a whole. He outlines those risks in his discussion
in titled Arctic warming risks for methane emissions. Sea ice loss and ocean overturn. Welcome to Cambridge form Randall print. Thank you. The only thing I'm afraid of is I've only got 20 minutes for professors at a place like MIT and I'm sure the same is true at Harvard. We're used to speaking for hours. OK so the topic is already being announced. These views of planet Earth from the Terra satellite and the one in the middle of the top row is what it really looks like and all the others that you can see the continents and so on have been felt some of them that had the clouds removed some of them are moving slowly so that you can see the change of vegetation on the land and the change of phytoplankton densities in the ocean. The
top right hand via the sort of cloudy one and the one in the middle. Of the bottom are these. Images of infrared radiation going from the earth out to space. So basically we've got a simple thing. The climate and in the simplest terms we get energy from the sun and which we absorb as a planet and then we call ourselves down by emoting infrared radiation out to space. If these are an exact balance then we say we have a stable climate. Doesn't the overall of global average temperature should not change in all 20 averaging time periods. We are not in fact in balance at the present time. And I'll say something about that imbalance shortly. It's something that you can't see in those. Me is that is very important about the
climate system today and that is the human influences. And I'll be saying something about those as we proceed. But let's just look back in time and by drilling down into the ice caps you can get older and older ice the deeper you go and you can look at the ice to talk isotopes of hydrogen and oxygen in the ice and will go through the technical details but you can back out an estimate of the temperature of the snow that precipitate it from the atmosphere and then built up to form. The the ice the ice sheet itself. You can also take hunks of that ice and you can crush it all up and release the gases that were trapped in tiny little paws in the ice. Right. So these archives of old all they are. And the record and the Vostok ice core which is at the great dome of talk Tika goes back more than 400000 years
horizontal axis here is thousands of years before present BP is before prison not the oil company. The inferred temperature is on the hard on the left hand axis and it refers to the red trace that you see there and the temperature is just listed as a deviation from roughly today's temperatures all more strictly those of the around the 1950 time period as just a point of reference. So. Remember that today is zero. It is on the left hand side of the graph and 400 this 100000 years ago so it's the way it's being plotted here. So here we are this is temperature then as the red trace where in the Holocene which is ground zero there and then is you see as we go back in time say ten thousand years can be just dropped and you can see by about eight degrees centigrade or so and then I bouncing around bouncing around the top of the Red Arrow is about a hundred and thirty thousand
years ago and it's called the Eemian period and that was the last warm period as we are in now where in a warm period also cooled into glacial right. It's a technical name for this interglacial laborin is a policy of the previous one is called the Eemian. And you can see that and these temperatures that are shown here are polar temperatures in this case the Antarctic region temperatures because that's where the snow full of precipitated the flow in the Antarctic ice sheet. Now what drives these natural to what everything you see here is natural. This is what the system does but remember this 400000 years being shown here right now I'm going to emphasize in my talk that what we're talking about for climate change now is the next couple of hundred years. That's not even resolve that time scale is not resolved on this. So this diagram is often misused by people who want to give an impression that the natural system is so variable
that anything we do is negligible and in comparison to these this is 400000 years not 200 years. So that's the raid. And then why the reason I wanted to really look at this is also let's look at the concentrations of a couple of the most important long lived greenhouse gases in the ice cores tracked in the ice cores. So this is all there. So here is carbon dioxide is the top right. And that's measured in parts per million. As you can see there on the right hand side with the blue numbers and you see that it seems to follow the temperature up and down up and down with the temperature not precisely. But then methane the one of the. Things in my title is follows the temperature almost slavish up and down up and down it's a remarkable correlation. And to an engineer This is called a positive feedback.
Why do I say that when temperatures are rising the red curve is rising. Right. The carbon dioxide and methane levels are rising. Right now those are greenhouse gases. So if they rise they accelerate the warming. And so if it warms for some reason the greenhouse gases seem a natural cycles to increase with the warming. And then if I get cooling of the system then they decrease. But I can turn that around chicken an egg and simply say well maybe the greenhouse gases rose a little bit. And then the temperature rose and then the greenhouse gases rose more. Right. That's a positive feedback to an engineer. And when you hear positive feedback for the climate system it's bad news. We would love to have a climate that was all negative feedback where we push it in all directions and it comes back to a stable level that's what negative feedbacks do. So although the positive and negative would sound as defining whether it's good or bad they are defining weather.
When you disturb a system do you does it accelerate away from that point or does it go back to a stable point. So we are looking at a climate system that has positive feedbacks to do with the greenhouse gases and that's bad news right because it means if we increase greenhouse gases leading to warming the warming itself will induce the emission natural emissions of greenhouse gases. That's what this diagram is telling us. Humans have nothing to do with what is there. So this is the natural system. So that's a warning to explain these temperature changes as I say you require a lot of positive feedback sets to amplify the very small changes. And we understand that. That's Jim Hansen may say something about that in his talk later in the day. We've we've got to have these small changes in the solar imports now those small changes occur by what are called Milankovitch cycles. Right. These are tiny variations in the Earth's orbit and
those need to be amplified enormously to give us these big temperature changes. And you can explain these temperature changes if you take into account all of these other rising the Gries and greenhouse gases that accompany these changes or the lowering of them that accompany the cooling period. So it's a reasonably consistent picture. What about the last one hundred sixty years. Here is a typical record of how temperatures global average temperatures jump up and down year to year. And this is just for the thermometer record. What I was showing you before were inferred temperatures from the isotopes in the ice. So these are real temperature measurements and you can see year to year since 1850 temperatures a bounced around up and down year to year. And then if you look carefully you can sort of see trends right. You can see some ups and downs over 10 20 year time frame and then overall if you think of climate now as the average of a tan or 20 or 30 year
time periods rather than the year to year then you know you might look at this diagram and see something like that. Just That's not intended to be a mathematical fit or anything at SR. So there it is you can see that it bounces up and down on these longer time frames right beginning in 1850 Rosabeth when then went down then around 1910 began to rise and then around 1950 or so DH began to go drop down for 10 15 years and then since then it has just steadily risen. But there are these year to year variations. Right now if you want to plan to do mischief you can just take the last. Ten years of this graph and because 1998 was one of the warmest years ever seen and if you just show that then then you'd conclude the world was cooling. People who do that. And then if you want to exaggerate the warming you can choose a different parit right and you can say it's warming by a much much greater than the
scientists would say that it's going to warm. So you can look at these long term trends. That's what it looks like. And because it's not nice and even and smooth it does and I have all various interpretations and I'll come back to those interpretations in a minute. There is another very worrisome trend because now I want to go back to the polls right. And let's have a look at Arctic sea ice at the end of the winter and at the end of the summer have evolved. Now this is images from holding satellite so the record begins in 1979. So here is that record. All right. Beginning in 1979 the black dots and the things joy and the lines joining them they often mocked in the Arctic which is the end of the winter. Think of that as the end of the winter and the red summer the end of the Somme a September right. And these are relative to the mean values for the 79 to 2000 period so to look at the percentage difference
over this time frame to predicts pressures as a percent. Most people are better able to think about it rather than millions of square kilometers and so on. So you can see that the red dot and focus on knows one thing that you see remarkably is the big draw. That's a could recently. And the smaller ice extent in the Arctic since measurements began occurred in 2007 and it was one half of the ice extent that we had in 1979. It had gone down by a factor of 2. That arctic sea ice and this is real measurements. Images right. So there's absolutely no doubt about this data. The red and the black lines are the red Linea lines the straight lines through the whole set of dots is just a linear trend. So let's have a look at what those trends are. Ok over that time period for the black curve over all it's sea ice in
the winter the end of the winter is dropping two and a half percent per decade. And for the end of the Somma it's dropping at eight point nine percent per decade and that the long term trend. And again be careful when you look at a diagram like this that the year to year variations probably simply natural variability in the good scientific reason to expect that. But the long term trend can only be explained of course by warming and we know from the temperature curves that I showed you that 79 onwards was a very significant period of warming the Arctic and Antarctic particularly the Arctic warms at about twice the global average. Right. And there are good scientific reasons for that as well. So. We've got temperatures rising and we've got Arctic sea ice. Dropping very rapidly for it to go down by that much. Close to 9 percent every 10 years is very worrisome. So in 2007 I was in the
Arctic night on the polar class. I spike a cold happy tongue in a cough and that is it. And that's what you hope to be and when you're up there there's lots of ice and if you ever get the chance to go on a polar class icebreaker grab that. But I'd advise you to do it fairly soon right. Given the graph I just showed you. However we were there for 11 days and only two and a half of those days were like the talk left and emit more typical was what I'm just showing you now I took this picture from the shore we've gone ashore in on Zodiacs. There's lots of things up there living things up there on the most of course the ones that people worry most about. Of course Polo days whose livelihood depends on plenty of ice and which they can go out and get to the SEALs. And there are a few toads of wool Russ and of course various types of
seals and so on. So it's a very spectacular place. But as I say the bottom left hand photo was typical of the voyage not the top left hand photo. Now methane is rising again. And I'll show you both the I was mentioned in the introduction that I've been measuring greenhouse gases on my colleagues of many years. And what you see in the lefthand graph at the top of it there is just a. Day and then the low of this right. Right. They began it. It's rise again which got into the news and that's shown. In this other. This will put it here.
You see where I've got the ellipse heah. The stations that you see there range from the end of the Arctic region at the top to Tasmania at the bottom. And what one sees in these graphs is that the increase did not occur if first in the Arctic and then later in the Antarctic or in the south. The rise began in all places. Right but it was all rising much quicker in the northern hemisphere. But interestingly it rose in the southern hemisphere as well. And how can you interpret that so this got into the news we had of the paper and Geophysical Research Letters. And we then interpreted this with methods that we developed to interpret these measurements in terms of emissions and without going into the all of the details. We found that there were two possible explanations for what we were seeing. One was that
we would simply getting emission increases in the two hemispheres 40 Tarif grams per year Terra gram it's 10 to the power two hours a trillion grams OK that's 40 Tarif grams per year increase. From 2006 to 2007 in the northern hemisphere and 20 to Tara grams in the southern hemisphere we needed the southern hemisphere emissions to increase because we saw that increase occur almost simultaneously but slower in those days. However there is another explanation and we have another gas that we measure that is proposed that enables us to estimate the sink the methane the natural sink for methane which is a chemical sink in the atmosphere. Those of you remember some chemistry the hydroxyl free radical is what it is and destroys methane. Thank goodness it's there because methane is very very powerful greenhouse gas about 25 times more powerful per ton than carbon dioxide. But if this hydroxyl radical sink decreases
then that would be the same as a as an emission would appear to be the same as a mission. The saying that's the same as over all and the tendency of increasing the salt and we think this is the bowl probable explanation is is this. And that meant that the increase then in the northern hemisphere which we do attribute to be the Arctic. It's about 20 Terra grams per year and. What 13 Tara grams per year and all of the hemisphere and 7 Terah grams in the Southern Hemisphere with the Northern Hemisphere increase being pretty much the Arctic. So why would one worry about that. I'll tell you this that in the Arctic has all point out there's a huge reservoir of carbon waiting to be emitted and all you need to do to stop the a mission is to melt the permafrost. Welcome back to our policy goals the common way is to talk about policy goals for example that the Copenhagen conference was to
talk about keeping greenhouse gases at some. Pre-determined level that everyone agrees on. There's a lot of talk about stabilizing at 350 parts per million I know Jim Hansen likes that number. Four hundred fifty parts per million other people talk about. And these are carbon dioxide equivalent to you convert all of the other greenhouse gases into their equivalent of carbon dioxide which would have the same effect on climate. So that's just a little calculation the scientists like me can do. So I we measure these greenhouse gases all the way around the world right now we are at four hundred seventy parts per million of carbondioxide equivalent. So people who talk about stabilizing at 350 are actually talking about vacuuming and not lowering emissions about vacuuming. Right. Greenhouse gases from the atmosphere it be wonderful if we could work out how to do that without ruining our economies. But that's just a caution. As a scientist I would like to see a stabilize at levels that we've
already seen. My cousin would say way at least used to that. So we might go and say what about the level that we had in 1950 or something like that because we've now been you know experience that for 60 years plus. And you know we we see that the planet is not radically changing although those Arctic sea ice changes are worrisome. The other goal talked about is to keep global temperature increases below specified amount. Now another problem here is that according to the diagram I showed you early on we're already about point eight degrees centigrade above pre-industrial. So a lot of people talk about let's keep it less than two degrees centigrade above pre-industrial right. So that means we've got one point two degrees to go right. But it's even worse than that because we're already committed to point six degrees centigrade of warming for the current level of greenhouse gases that we have even if we just stabilize right now we would get another point six degrees centigrade of warming.
Right because why because the ocean is not in equilibrium and it would have to be warmed up. And we know that slows down the rate of warming but it doesn't change the final temperature. So that's a warrior that would mean point a plus point six as one point four so we're left with only point four degrees centigrade for us to be allowed for increases and the missions that might come from China and India even if we go drastically down. So this is a heck of a tough problem. It is not an easy problem to solve but we have to solve it. So I'm going to have to speed up I think we use a model to model the system that is the most complex of its type in the world and it is especially distinguished by the fact that it is a model of the global economy. Each major of the economy of the world is modeled all of its sectors of agriculture and energy and so on a model and then associated with each human activity the amount of greenhouse gas and air pollution emissions are
projected forward. And we checked this against of course measurements of the greenhouse gases to deny knowledge of the economies of the countries. So that since these greenhouse gases those are in the black. Black box there into a model of the US system which is got all the elements of a climate model the atmosphere the ocean the land the physics of those those entities but also the biology on the land and in the ocean a very important in the climate system as well. We separate urban areas from the rest of the areas on the land in order to handle a pollution. Exactly. And then we have all sorts of outputs of GDP things like GDP rainfall temperature. The amount net park productivity of eco systems and so on and we are able to use this apparatus to answer questions such as well if we stabilize at particular levels right how much will it cost. In the way of the policy.
What are the damages we avoid. Right. And yes so questions like that. Now the problem with the climate system and why there's all sorts of debates among scientists is our ability to forecast climate. I will admit to you is uncertain when we don't know exactly what's going to happen. So what we do is we run this model for a particular scenario. Let's say we were going to stabilize at some level we run it 400 times with different assumptions in the economics model and different assumptions in the natural climate system model. Right. And we run up 400 times on a Monte Carlo sands and then we look at the right. We don't pertain we can do it exactly we just look at the range by the way this is how long forecasting is done you know over periods of one or two months. They do 40 or 50 or 60 forecasts and they
give a range and they give the odds of various outcomes to the farmers who appreciate it particularly when it's accurate. So here are the results of the odds of exceeding various temperature targets if various policy targets so the five policy targets the one at the top is a policy it's called no policy. That's what we're pretty much doing today. We have no call to stabilize at 907 ninety six sixty five fifty these a part per million of carbondioxide equivalent. But carbon dioxide is a significant fraction of those equivalent. Sure I did and in all other cases. So this is giving you the odds of exceeding two degrees centigrade above 1990 levels are in this column. The black numbers. So you see even if I stabilize at 550 I've got 25 percent chance of exceeding two degrees centigrade from 1990 one of the red numbers. If I take the basis as pre-industrial say 1850 temperature
then the odds of exceeding 2 degrees centigrade if I stabilize at 550 we're already extremes 470 is 80 percent. So that gives you a real sense we've got a problem here. I've already told you where in 470 we 550 would seem to be something we could with a lot of global effort global effort. We might be able to make it but there we have to target this lesson to do resound right we have a problem. So. I will move on from there. If you look at the polar temperatures in now at you now. Projection. So this is going from the left hand side as the South on the right hand side of these graphs is a northern North Pole and the median all the average if you like is the temperatures there for the five policy cases that I showed you right. And the upper 95 percentile is the one on the left and you can see that in that percentile the operations of a 16 degree centigrade polar warming Arctic warming.
16 degrees centigrade. What does that mean. So what's up there. How do you know for sure on all ice already made that point. It would totally disappear. But what about the permafrost. This these little yellow arrows the hybrid lines that you see at the base of the arrow that's where the permafrost line is today and that's a projection just for two and a half degree centigrade. Global warming a five degree centigrade warming of the Arctic region. And you can say that the extent of the tundra is very drastically reduced if we went to 16 degrees centigrade we would melt everything. So who cares. There's about sixteen hundred seventy billion tons of carbon stored in Arctic tundra and frozen soil. What does that mean in terms of what we do today. It's about equivalent to over 200 years of current carbon emissions from the burning of fossil fuel and it's sitting there it's of reservoir This is the
smoking gun that people worry about. If we activate that and it'll be activated as wetlands with methane coming out of them. That's why everyone got excited when we published our paper in 2000 like 2008. They said Is this a smoking gun. OK so I'm going to a two minute warning I've been given for doing they did that in football or something. We can project forward and we do. In this model and actually show that if we allow the world to warm up. As in the polar regions we do increase the emissions of methane very substantially we're worried that we're underestimating that increase by the way. But that's one of the big drivers of the increase in warming is the fact that greenhouse gas and natural emissions are beginning beginning to be activated. So that bad news it's a positive feedback by the way. It's a positive feedback you remember how methane slavish we followed the temperature record and the ice
call recode. So hearken back to that. It did occur. And here it is for the potential. The ocean is turned from top to bottom in it and it's very very important for the climate system why the ocean is taking up heat and it's taking up carbon dioxide. One quarter of the emissions of carbon dioxide. Very fortunately being buried in the ocean on the 20 year average buried in the ocean one quarter if that ocean didn't take that up. A quarter it would be in the atmosphere right it would be in the atmosphere. Is this sink stable. You've got to stir the ocean from top to bottom to get the heat and carbon sink to be effective. And there was that speculation is driven just in these regions of the world the world oceans right the North Atlantic and the circum Antarctic the Ross and Waddell seas that you see down there and in the North Atlantic. Could you clothe us down and you can slow it down you slow it down by decreasing sea
ice. And increase freshwater imports into the sea. Well all climate models show increased precipitation with warming. No surprise in the precipitation percentage precipitation increase is greatest in the polar regions. Why. Because when the more moist more warm atmosphere you can carry more moisture and you carry more moisture to the poles and you get more snowfall and rainfall depending on the temperature. So unfortunately that means that the things that slow this top to bottom circulation are what we expect from global warming. So we have another thing at risk. And the calculations were done with the ocean model within that big global system model I talked about suggest that if we exceed about 600 20 parts per million. Then we will. Offend shut this circulation down because of the increase in freshwater imports and the lack of
sea ice formation. All very low for sea ice formation and want to shut down. It just stayed shut down for another nine hundred years even if we stabilise carbon dioxide levels want to shut down if it stayed down. The ocean is a very complex system and it's got a big big time constant associated with it. If I think water in the polar regions of the top of these arrows Typically it will be a thousand years before that water reappears at the surface again if it goes down to the bottom. So that's one of the problems with that. Once we disturb the deep circulation it's a long memory. So this is the final. View graphs of dog view graphs that I'll show what I've got here is what we're doing today. This is no policy we'll we call it the greenhouse gamble and this is just showing you the odds for the case of no policy that I showed you earlier in the I was the one where we got to fourteen hundred parts per million of carbondioxide equivalent by 20 100.
So here are those odds. So you see that. Three degree said. Let's look at the three degrees centigrade of our Ninety seven percent chance of exceeding three degrees centigrade and that means six degrees centigrade Arctic and Antarctic warming. But more in the Arctic less of me and talk to me. So this is a dangerous week. How much sea level rise would you get I believe there's a speaker going to talk about sea level rise fall leave that to him. Well good. So this is not a wheel you'd want to spin. We stole this off Vanna White. By the way those of you old enough what would we buy a stabilization even at 660 right. And here's that wheel. As that wheel the odds of three degrees centigrade and greater warming of dropped drastically. Now there are only about 10 12 percent chance instead of 97 percent chance and that's the nature of stabilization
and the nature of how the climate system responds to it that leads to this. And we're spinning this wheel today right. And I would opine that we should at least be stealing those spinning the wheel that's on the left hand side. Or even better the 550. And if we could ever afford a 450 but I think 550 is what we'll probably head to the Right now as most of you know nothing is being done. Nothing. You indicate that the methane may be the smoking gun it sounds more like a flaming gun I mean it would be something that would happen interruptive force would subject the ocean clathrates that is their methane gases that are trapped within the oceans themselves. Yeah I think I call it a smoking gun because I can't prove right now that we're absolutely on that track we've seen we saw increases in methane. They began in 2006. The rate of acceleration of those
emissions was greatest in 2007 through 2008 and now it's settled down still increasing but it's not quite the right that it was increasing in 2007 and 2008. So we have got our finger on the pulse right. Think of it as a smoke detector right. And so it's. We'll watch it. We will watch it. The problem in the US the climate system would be sort of nonlinear or threshold some people call them threshold tipping point. The name isn't maybe a little exaggerated to the white. Things are really working it is a positive feedback these are positive feedback. That's worrisome because once you start from these positive feedback accelerates you away from the state you were in and moved to more and more. And in this case to a warmer and more my system. So as a scientist that's what I worry about most or I just I don't want to go anywhere and there are these situations where the positive feedbacks begin to take over. To to then lead to changes that exceed even those direct things that way of forcing
through our own initiative. And there's risk and I think how you respond to that rush just depends I think on you know why what worries you. Right. My view is we only have one planet to live on in the next 200 years maybe in a million years or 10000 years from now that's a different story. But that's irrelevant. Let's just look at Aleck's two or three hundred years we know there's only one planet and we can't head west like we could do 200 years ago. That's what makes me concerned is that if we. Move into a world that's got all these positive feedbacks all activated and I can tell you exactly what level of greenhouse gases would do that. Then we're playing a big game. That's why I call it the we call it the greenhouse. You say you know my name's Jim Laurie and you made a comment about the biggest way to break down methane in the atmosphere was the hydroxyl. Yes and I just wondered what is it I don't really understand what your thoughts were on that.
Yeah so this is pretty complicated chemistry but air pollution produces I was right. And I with this is a rather interesting and ozone and lead with water vapor is able to produce this hydroxyl free radical. So the interesting thing is that one way we could lower the hydroxyl free radical inadvertently of course as we would lower our absolute intimate air pollutant emissions and it's one of those things where you suddenly say Oh what may be good for one thing is not good for the other. So that's a complication but we do monitor 0 8 levels right now. Hi my name's Peter Wood I'm more and hopefully this is a simple question maybe too simple but is there a particular canary you're keeping your eye on in the mind right now. I would say there's about 10 different areas one of them. All right and so I think one has to look at as I often do
when I give talks about the things I'm most worried about they are the polar regions because they are warming much faster to die than the global average warming faster particularly the Arctic them we have in our models. So I look at the Arctic and as the next speaker I'm sure will point out if we melt the ice sheet even parts of them we're talking about massive sea level rise. But I'm not going to give numbers because it stealing founda from its square footage for us. So two things I would say the temperature because I'd be thinking about the activation of the melting of the tundra and the release of these greenhouse gases. And secondly I'd be looking very carefully at Greenland and Antarctica assessing the rate of melt the rate of net loss of our beloved. Look at those above all those to that but I could make a list 10 times longer than that but those. So these two canaries.
The question is what's causing it and can we do anything about it. As far as I can understand in Roman times and in medieval times there were both warm periods which were warmer than it is now. And of course there was not an industrial civilization. Several million years ago there were I believe 20 times more carbon dioxide in the atmosphere than there is now and there was an ice age from the books I've read and I understand that changes in the sun namely the increase or decrease of sunspots which emit. Magnetic radiation and cosmic radiation from outside the solar system. Those. Sunspots make the climate get warmer and when there are no sun spots the climate gets colder. Also at the moment whilst the northern polar regions are getting warmer. Antarctica except for the peninsula pointing up
towards Chile is getting much colder. So far as I understand does the main cause of warming in the atmosphere is water vapor. About which we can do a little me thing about which we can do a little. And carbon dioxide virtually not at all because there's no point no 3 8 percent of carbon dioxide in the atmosphere which is I believe one ten thousandth as much as there was in 1750 So a tiny amount of it of a tiny amount of carbon dioxide of which we contribute about 3 percent so we contribute virtually nothing to what is virtually nothing in the atmosphere. Here's the question. Going to the lineup. Yes we are as well. Well Ray you frame a question that I can well my question is what is causing it I'm sure it's not carbon dioxide and I'm sure it is the sun and we can do nothing about the sun so can we do anything about it if it is the sun.
And if it's changes in ocean currents neither of which we can do anything about. I want an earth you think I can do. So you've searched first you said changes in the sun. We have been monitoring the sun and the satellite age with great accuracy. And you can look at the very tiny changes in the total output of energy from the sun that is actually capable of being absorbed by the earth. And I'm afraid you cannot explain the warming in since 1979 that we've seen by anything that's going on in the sun. So you mentioned the changing and ocean currents. Right. And and so how do you think a change internal change is going to change the total amount of heat and in the system how will it change it. We've got to put more energy or less energy into the earth right net and so circulating it around you know can do ups and downs regionally circulating heat around in the ocean and in the atmosphere but you can't change the global average temperature in that one.
So you mentioned that that those will warm up I know of no credible evidence that says they will warm or they will suddenly warm up areas right. But you can. All of the reconstructions I've seen using tree ring data in a variety of other data which are not accurate thermometers. Show that the warmest periods of the warmest times we have had sent in the last 100 years have been in the last couple of couple of decades up and down. I tend to read the peer reviewed literature. Right I am different than that. I'm a scientist so so I'm well aware of this Bach and many other books. I go to the peer reviewed literature when I have methane increasing. Where did I go I published it in the peer reviewed literature and that's what as a scientist that's what I rely on. And I'd advise everyone in this room don't believe books. Don't believe blog don't believe
websites unless you can then go and have the peer reviewed literature rely on the peer reviewed literature. That's what scientists do. That's how we define our credibility. We don't define our credibility by writing a popular book. We don't define our credibility by having a blog like that that automatically going to whatever one does. They were blogs on both sides of this issue and that terribly confusing to the public and I'm sorry but I don't have a blog and I don't write popular books. I've just decided to publish it. OK one more question and then we'll have to move along. Your comments very much lead to my question which is it's my impression that possibly a lot of the actual monitoring I mean actual data that's collected is quite ad hoc. Do you feel there is a coordinated effort effort by the scientific community to look at the many components you've described in sufficient detail and you know so that we have you know sort of an ongoing
database that's very reliable right. I think in general we do have to realize that our capability to measure everything that's going on in the climate system is limited. Unfortunately I wish that people 500 years ago and got the monitors and began a set of measurements with the mammoth as 500 years ago and then the question of was this gentleman here brought up. We wouldn't be relying on tree rings on a car off the road to give us a sense of what was going on back then. And these are tree rings that are largely in a very tiny area of the world where will it trees last for twelve hundred years or do you know they're still there so I wish we had a better knowledge of how the Earth has changed particularly in the last few hundred years because that's the time frame we want to look for. I wish we had better knowledge. That's why in our projections you'll notice that we had a very wide range those wheels had a long wide range of temperatures and that's because the observations of the climate system say in the last couple of hundred years
Cambridge Forum
WGBH Forum Network
Arctic Warming: Risks for Methane Emissions
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WGBH (Boston, Massachusetts)
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Episode Description
Dr. Ronald Prinn, TEPCO Professor of Atmospheric Science in MIT's Department of Earth, Atmospheric, and Planetary Science, shares the result of his project measuring the rates of change in atmospheric concentrations of trace greenhouse gases. After more than 30 years of research, he and his colleagues recently noted an unexplained increase in methane concentrations which led them to reconsider the impact of methane vis-a-vis climate change. He outlines those risks in his discussion of "Arctic Warming: Risks for Methane Emissions, Sea Ice Loss, and Ocean Overturn." This talk is part of Cambridge Forum's After Copenhagen: Global Climate Change Conference, recorded by Steve MacAusland.
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Distributor: WGBH
Speaker: Prinn, Ronald
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Duration: 00:00:00
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Chicago: “Cambridge Forum; WGBH Forum Network; Arctic Warming: Risks for Methane Emissions,” 2010-01-28, WGBH, American Archive of Public Broadcasting (GBH and the Library of Congress), Boston, MA and Washington, DC, accessed June 26, 2022,
MLA: “Cambridge Forum; WGBH Forum Network; Arctic Warming: Risks for Methane Emissions.” 2010-01-28. WGBH, American Archive of Public Broadcasting (GBH and the Library of Congress), Boston, MA and Washington, DC. Web. June 26, 2022. <>.
APA: Cambridge Forum; WGBH Forum Network; Arctic Warming: Risks for Methane Emissions. Boston, MA: WGBH, American Archive of Public Broadcasting (GBH and the Library of Congress), Boston, MA and Washington, DC. Retrieved from