 and welcome everyone. The water is, unlike the Pacific Ocean, I'm going to take the water as being warm. Pacific Ocean off the coast of California, Central California anyway, is rather chilly. Well, yeah, ocean, you know, not lake. So welcome everyone. Thanks for showing up here at Science Circle. My thanks to our hosts for organizing this. So the theme is, this isn't your grandparents climate, that there have been changes over the years. We're no longer in the pre-industrial climate. Joss, how do you normally handle questions? I'm okay with people asking them. So we're here on the Earth, a small rocky planet, orbiting a main sequence G2V star. We normally call it soul. Near the rim of a spiral galaxy, the Milky Way. Sitting there in space, the Earth orbits around soul, absorbs energy from the Sun in the UV visible wavelengths, and then if nothing else happened, the Earth would start getting as hot as the Sun eventually. But avoiding that, the Earth emits energy to space in the infrared long wave. And the two occurrences, the sunlight coming in and the infrared radiation going out, are separate enough that in modeling they can be treated separately. The infrared is generally taken as longer than four micrometers in wavelength. I like this quote from Marshall Shepard, who is a past president of the American Meteorological Society, and stated, weather is your mood and climate is your personality. It takes a while to learn a person's personality, and it takes a while to figure out what the climate is, whether you just sort of have to walk out the door and look up and notice that it's raining, and sure enough it's raining here. Well, get into that global warming versus climate change along the way. Global warming is generally taken as a single number, the global annual average of the temperature change. So it's easy to plot as a trend, yes. Whereas climate change includes everything beyond that single number, including a geographical distribution of heating and all the things that the heating causes. So the business of the Earth, in many ways, is to balance energy, to absorb energy from the Sun, and reflect some of the energy the Sun gives us back into space. But, oops, okay, thanks for letting me know. So the Earth is basically a system of energy balances. We receive energy from the Sun, partly some gets reflected back into space, but 67 watts per meter squared is absorbed by the atmosphere, and 168 watts per meter squared is absorbed by the surface. The Earth emits, surface of the Earth emits radiation, infrared radiation, reflects some of it back from the atmosphere. But what makes it out is 235 watts per meter squared. Think of the Earth as a disk, as a G. So the radiation that actually comes in is in the facing disk of the planet. Yes, it's allowing for the inclination and that part of the Earth's surface is blocked by the rest of the Earth. So about 235 watts per meter squared of infrared radiation goes out to space, and when things are in balance it just happens that 67 and 168 got up to 235. So this is pre-industrial. Basically the heat from the Earth's core is insignificant. It's way down there. Remember these are numbers per meter squared. We should be grateful for natural global warming. Basically carbon dioxide is emitted from volcanoes at a slow rate compared to what we're doing now by human efforts. Then the carbon dioxide is absorbed by weathering of rocks, making carbonate rocks, and by sea creatures with shells that make a carbonate shell later die and the shell ends up on the ocean bottom. An interesting feature of Earth is the emission of infrared radiation depends strongly on the temperature and strongly being the fourth power of the temperature. And the effective radiating temperature of the Earth to balance the absorbed energy from the Sun is minus 18 degrees. That's kind of chilly. Remember that's the average temperature. It would mean a lot of places we live in would be totally too cold. But the actual surface temperature that we experience on average is about plus 15 degrees centigrade. So there's a 33 degree difference between the effective radiating temperature of the Earth and the surface temperature of the Earth. And that is a natural balance of carbon dioxide and methane in the atmosphere, pre-industrial. And there's no physical reason to infer that the warming of CO2 is going discontinue at the pre-industrial level as we pump more and more CO2 into the atmosphere. We're historically living because of the CO2 and methane and we may find ourselves uncomfortable because of our changes. So water, we seem to have some water here today, but water in the form of water vapor is a stronger greenhouse gas than carbon dioxide. But the concentration of water vapor that's in the air depends on the temperature. And carbon dioxide and methane, because they don't precipitate out, act as control knobs on how much water vapor is in the atmosphere. Lasis and colleagues did a simulation of what would happen if the CO2 and methane were instantaneously removed from the atmosphere, but initially leaving the water. And in 50 years, the planet had cooled to average temperature of minus 21 degrees centigrade, and there was virtually no water vapor in the atmosphere. Yes, with the temperature of, as the carbon dioxide moves the temperature up a notch, more water vapor can exist in the atmosphere, and that water vapor is a stronger greenhouse gas. So that if the temperature went up by three degrees, which is similar to what's expected from doubling carbon dioxide, two of those degrees would be due to the extra water vapor and more violent storms. When it gets warmer, you have a heat of evaporation of the water off of the warmer oceans and the warmer air, and that is latent energy that as the water vapor condenses, it liberates that energy back into a storm, and so more water, more energy. This is a simple analogy of what's going on to get us the greenhouse effect. If you put a light in the bottom of a cylinder of water and look down, you know, with just the water, there's no problem. You see the light sitting on the bottom, but as you start to add ink into the water, squeeze an octopus or something, in order to continue to see the light, you have to move the light up. That's sort of, you know, obvious to people with a cylinder and light, and by the time you add a lot of ink into the water, you can only see the light if you've moved it up a fair amount. I'm hoping that makes sense. So the same thing happens in the atmosphere. The CO2 is a strong absorber, and when you add more CO2, the altitude from which the atmosphere radiates to space, or conversely, from which a satellite can see down to us, also increases, just like the cylinder. And in the troposphere, the higher the altitude, the colder it is, and colder means less energy is radiated to space, back to that fourth power of temperature. To get that emitted energy back in balance, because now the Earth, as you add more CO2, is emitting less energy, you have to warm up the new altitude from which radiation goes out to space. And the temperature at that altitude is tied to the surface by convection. And that's basically the physics for global warming in a nutshell, that you increase CO2, you raise the altitude from which the atmosphere can see space, it's colder there, and that means less radiation is going out, but the same radiation is coming in in terms of sunlight. And that means the Earth is taking on more energy than it's emitting out. And in one sense, that's the definition of warming. It may not always be temperature that changes, but that's the global warming effect. And you can search on that in terms of some of the effort of putting that energy in terms of cat sneezes as a unit. Now it was known much earlier that carbon dioxide absorbed infrared radiation, but starting in the 60s, the Air Force cataloged all the absorption lines of CO2 and other gases. Well, it depends on the particulates, Vic. If they're sulfate aerosol, aerosol means small particle in the atmosphere. If they're sulfate in aerosol, they tend to reflect sunlight and the air cools a bit. If they're carbon particles, then they tend to absorb sunlight and energy. And that would tend to heat the atmosphere. Sorry if my voice is a bit scratchy. I was on travel to a conference a week and a half ago and came back and immediately came down with my travel cold. It doesn't take a climate model, a full climate model, to estimate global warming. Back in what's become a classic paper back in 1967, Suki Minabi and Dick Weatherall used a one-dimensional, so it's global average, but has varies in altitude. It's got a whole altitude profile. A radiative convective model, which means that it handles sunlight and infrared radiation and it convicts air up when the atmosphere becomes unstable. The density allows the upwelling radiation. Same stuff that holds up gliders in the atmosphere. They were able to calculate a change in average surface temperature from doubling the concentration of CO2 of about 2.4 degrees. And probably two-thirds of that is due to the water vapor that is added to the atmosphere as the CO2 warms it a bit. And that number is still solidly within current estimates on the effects of global warming. We also noticed a signature of greenhouse gas warning that the troposphere warms because more radiation, more infrared radiation, gets trapped with it like a blanket and a cooling stratosphere. Because if less radiation is escaping the troposphere, then there's less radiation going through the stratosphere and that basically cools it. So that signature matches observations. You wouldn't have that signature from the more active sun, for example. And that supports the idea as well as with other physics that the carbon dioxide is causing the warming. I'm not familiar with Eunice and that's unfortunate if she did do the experiment and not receive the recognition. I'd be interested if, well I can look up the paper myself. But I would be interested in that. Thank you, Tackling. So going away from the physics from a moment and how that motivates global warming. We also have observations and analysis from a number of groups now. Unobserved heating, both from using tree rings as a proxy for temperature. And after 1960 more direct readings. Basically the tree ring temperature followed observed temperature from about 1880 until about 1960. And around then there's emerged a problem that in the literature is called the divergence. It was published in the 90s and basically some of the tree ring data at high latitude stopped following the temperature. That could be due to acid rain or something else affecting the tree growth. It was known prior to the first analysis by Michael Mann in doing a temperature sequence like this. And he merged the two data things. Taking the tree data up to about 1960 and then merging into observed temperature when the there was less certainty about the tree data. Yes there's a, for instance, a whole very nice history done by the American Institute of Physics on global warming. I'll try to find that at the end of the talk. So both the physics and the observations, I think they took, depends on the base period they took. And I think they took a more recent base period of somewhere around 1900 to 1960. An anomaly is basically where you subtract off a base period to give you better numerical precision. You don't need to carry on the large number and do the whole analysis on that. So it's often done in terms of an anomaly, meaning the variation from something taken as the base value. Now I did give the link at the bottom to the Berkeley EarthOrg organization from which they took the graph. And their analysis and papers are online. So that information of what they used as the base period would be there. And in the early phases we have, well we still have, we have natural variation from volcanoes. We also have large uncertainties in the data. So beyond the observations of temperature increase and the fairly basic physics that I started with that points toward greenhouse gas warming, the total solar irradiance is measured from orbit and has little variation. And if anything, is at a minimum. So it can't be blamed on the, the heating can't be blamed on the sun. And currently the eccentricity that's the, how elliptic the orbit is versus circular is low and heading for a minimum in about 25,000 years. Cutting out climate change as a source of orbit, of from orbital forcing that in times when the orbit is much more elliptic and it changes because of the pull on the earth from Jupiter and Saturn primarily. When the earth is more eccentric, you can run into conditions where the northern hemisphere summer isn't sufficient to melt the snowfall from the previous winter and you know over thousands of years that accumulates in the ice sheets, which has been the basic mechanism of climate variation historically, historically meaning in millions of years. And either a change in the sun itself or warming due to orbital parameters, which basically also change the amount of sunlight arriving at the earth. Neither of those would have the signature I mentioned of tropospheric warming with stratospheric cooling. Steve Easterbrook, who's a climate, a computer scientist at the University of Toronto, embedded himself with the UK climate modeling group. And that resulted in both a paper on what he observed in development of climate models by the modeling group and also a fairly understandable talk on YouTube on what he observed on the methodology that is being used, which is not exactly what computer scientists might have expected. Yes, Vic. It's becoming more eccentric politically, but not orbitally. Just calculating global warming gives you a number of how the surface temperature is changing, but that doesn't really say anything about how the planet is responding to the energy accumulation of the earth. The planet, for its own reasons, can increase the surface temperature or it can melt ice or store energy into the deep oceans. And only the first, increasing the surface temperature, brings things back into an energy balance where the earth is emitting as much radiation as it's receiving. Now melting ice, particularly sea ice, decreases the albedo, the reflection of sunlight by the earth. Instead, the open seawater absorbs energy and that's going also act as a feedback. So a positive feedback in the sense that you melt the ice because of the increased CO2 and the energy imbalance. And now the earth receives or keeps more of the energy it receives. So that increases the heating. Well, Vic, about 40% of the CO2 we release into the atmosphere has been absorbed by the ocean that also acidifies the ocean, which is one of the problems. And as the temperature of the ocean increases, it can hold less CO2. That certainly is an issue of how long will the ocean keep absorbing the CO2? We've heated the earth. There are patterns to how that heating occurs. And both the atmospheric circulation and the ocean circulation read, distribute that heat because it's not even. More heat is received at the tropics than in the Arctic. And now, as an effect of the global warming, the Arctic is heating up about twice as fast as the temperate and tropical zones. Changing the circulation can change the amount and location of precipitation, meaning rain and snow. And warmer water can increase the evaporation, increasing rain, making a storm more intense. At the same time, the changing patterns can lead to drought in other areas. So that if the precipitation moves, what was an agricultural area may not receive enough rain. And the rain may have shifted to a different soil type, not as good for current crops. So that's one of the side effects. Climate models are also used now in sort of a new science of attribution, how climate change may have contributed to extreme events. It's somewhat salty soda pop though. So there's a new and increasing science of probabilistic event attribution, refer a post analysis of a particular event. One could run an ensemble, meaning a whole collection of slightly perturbed weather model, and look at the both with and without increases in greenhouse gases, and then look at the change in probability. That would be true for a particular event that you'd use a weather model. And in fact, that's what is done with weather, weather modeling now is running an ensemble of slightly perturbed runs and then looking at what might occur. And the probability of the event is compared for the two sets of runs and allows making a statement of how climate change may have changed the probability of such an event, or in practical terms for humans, the risk. And insurance companies and banks are reevaluating such risks. There's a recent two volume, fourth US assessment that's been released. Both volumes are online and I have the URLs here and these slides will be made available. These contain more than I put out in the talk, far more on both the science of climate change and on the impacts, risks, and adaptation in the United States. And well, preparing this, a rent across a tent talk by Yevon Schmidt, who was at NASA, still is I think, and gives a nice short review of emergent processes and model skill, points out that all models are wrong, that every model has to be an approximation to the real earth. But if a model helps you understand more, or with weather models predict more, then the model has skill. And so people talk about the usability of a model in terms of its skill. And this goes back, I think, to a statement by Tukey that all models are wrong, but some are useful. So that was my last slide. I'm happy to stand here and take questions as best I can. Well, that talk by Gavin Schmidt, let me raise the slide viewer preloads talks going forward, talks by Gavin Smith. He shows some nice pictures. One of the things one can take from the picture is that the current climate models reproduce observed features of the circulation, swirls of water vapor in the southern ocean, tropical cyclones and hurricanes. This is not in sync with the earth. And one of the things that confuses people is with weather prediction, you're starting with initial conditions that are current, integrating the model forward in time and losing interest when the model no longer matches the real earth. With climate modeling that isn't the way it's done. It's essentially a weather model. The what's called the dynamic core is often the same, although not the climate model may have less resolution, meaning the grid squares are bigger. But the features of the circulation in the atmosphere emerge naturally from the physics of the model. There's no code that says, oh, put a swirl here. And if you look at a global look at the model atmosphere and look at the observations at the same time, they look very similar. And if you were on the model earth, I don't think you could immediately tell that it wasn't the real earth. The simulations are that good. Different physics parts of the model are compared with observations. For instance, back in 1989, the atmospheric radiation measurement program was started, which has multiple sites, one in Oklahoma, where they take the atmospheric properties, clouds, weather circulation, and the radiation. So the two can be compared. And there's a lot of validation of climate models in terms of, do they have the right statistics? Do the various parts, when compared with observations, agree with those observations? And then it's all put together. And there are features that you wouldn't get from just any single part, but come from the interactions of all the parts. And one reason that climate models are such a useful tool. The IPCC, the International Panel on Climate Change, has a chapter on how models are evaluated. And that's at, yes, combining non-meat types of protein to get complete protein. I think corn falls in there somewhere, too, corn beans and legumes. Any questions? It is true that some features of the climate change are happening faster than predicted. Yes, and the more southern tree rings stayed accurate. It was some of the more northerly boreal tree rings that diverged from measured temperatures. From 1980 to 1960, observed temperatures and tree rings tracked very well. Well, not fires in permafrost so much, but permafrost melting, which can release methane. It also is causing problems in Alaska, where permafrost is getting mushy, with buildings. It becomes almost like standing in a puddle in the rain. Oh, we're doing that here. It's not always the number of hurricanes, although with more energy, that number can increase. But the intensity of hurricanes, because there's more available energy. Certainly more flooding. There has been a rise in sea level, and that mean, and couple that with stronger storms, and you have more flooding, basically, in coastal cities. So far, there hasn't been great concern that things are going to change enough that the methane stored at cold temperatures in the seabeds are going to activate. But that, of course, could depend on how extreme we keep emitting. There's still warning on hurricanes, and they track them. And that's one of the features of having monitoring satellites. And if we didn't keep replacing the satellites as they were out in their orbits decay, then we would lose that ability to give early warning. Support your local satellite launch, or national satellite launch. Our grandchildren will probably think we were rather selfish, greedy, and careless. Not good. Shepherds of the planet. Yes, and insurance companies are noticing increased risk, increased property loss from wildfires, from flooding, and that may make insurance in some places prohibitively expensive. Well, insurance companies actually do take out insurance policies. It's a re-insurance. So there's insurance companies for the insurance companies. Similar to crystal, similar to wildfires being the big problem in California, particularly after several years of drought when things become tinder-dry. I'm not sure that it would get to the point of being a bottleneck with seven billion people on the earth. But it certainly puts a large number of people at hazard. There are people who basically live on the flood plain in many countries. We're also seeing tropical diseases starting to propagate northward as the temperatures increase. So that's another hazard in terms of human health. Pine beetles have also, because many areas haven't seen as much of a cold snap as in history, pine beetles have been able to increase their range, increasing the danger of wildfires also. The assessment for the whole world would be the ice PCC reports. So the warming is changing the statistics of extreme events where they are now more biased to the hot side than to the cold sides compared to historical data. One interesting effect has been that the gradient between the tropics and the poles has decreased. The poles are heating faster than the tropics. That means that the sort of vortex of circulation around the pole is weaker, allowing outbreaks of polar air down into the 48 states. Some cold winter weather, but not colder annual averages. Well, paradise in California burned a year ago about fire, but that's a good question. And probably the hardest thing to predict is regional climate at this point. Vic, I think the answer to that is sort of like the correct answer for chocolate or vanilla, and the answer is yes. That some places will suffer drought, lack of water. The lack of food is interesting. They talk about virtual water exporting, and basically when you grow food or manufacture something, it often takes water. Certainly growing food takes water, and when that product or food is exported to another country, it's considered as an export of virtual water. And that movement north of say rainfall and productive areas is affected by soil type. It's not always the same soil type when you move 600 miles north, and that can drastically affect particular crops. Now we've developed, in a sense, specialized hybrid crops over the years, and flexible those crops may be to changes in location and soil. And season isn't clear yet. As the growing season changes, the blossoming season also changes, and that can screw up matches between pollinators and the crops. Thank you all for coming. I appreciate the audience and the discussion. It's always nice after preparing something to have people to present it to and discuss it with.