If a video has a question mark in the title, then the answer is always "no".
My previous video was titled "How can we test a Theory of Everything?" and the answer was not "no".
And the internet goes wild! Well, YouTube comments are coming in at a furious rate. No surprise at the number of which are climate change denial, without credible evidence ...
Yeah, there's something very wrong with YouTube comments. I have wondered if it's to do with the up/down voting that YouTube allows. Many people seem to use it, not to say whether a video is interesting, but whether they agree with its content.
Right, because 100,000 year old ice core samples aren't sufficient evidence to show 1) climate change has happened and will happen again 2) it was more catastrophic than human contribution for the past 2000 years 3) it will happen again, and happens as a natural cycle 4) You're myopic if you think your little blip into that cycle negates a pattern propagated over 100,000+ years.But yeah, no evidence. :eyeroll:
This is an outstanding video! Thank you for the presentation. This discussion encapsulates much of the discussion (or argument ) that is currently taking place on the AAAS forum. Dr. Palmer has condensed the current science concerns and prospects for improvement in a simply worded conversation. His brief, and guarded, synopsis of the difficulties facing governments and the world population was much to the point without belaboring the issue.Thank You Again.
I think this discussion might have been much more informative if you had included an academic doubter on this issue, such as the climatologist Judith Curry:https://en.wikipedia.org/wiki/Judith_CurryOften you find out more when you listen to two scientists with different points of view discussing the science.Perhaps you could still interview Judith Curry?
What "issue" is she "doubting"? Sorry, the Wikipedia page wasn't helpful.
Sabine,Judith is former head of the School of Earth and Atmospheric Sciences at Georgia Tech and is a widely published researcher: her blog is judithcurry.com.She does not deny that the planet has warmed in the last couple hundred years or that anthropogenic CO2 contributes to warming.However, she does maintain that some climate scientists and, most significantly, politicians and the mass media often understate the uncertainty involved in quantitative forecasts of future climate. My best friend from high school was involved in some of the early cloud modeling back in the early '70s. He impressed upon me the difficulty of the task because of the different scales -- molecular, droplet, cloud as a whole, and, of course, the climate system as a whole.I take it that clouds are still a nightmare computationally.Not an attack on climate scientists, just that cutting-edge scientific research, especially with multiple scales all of which are important, is really hard.Of course, this is one example of what Palmer refers to as the issue of "sub-grid parametrization."I suspect that you, Tim Palmer, and Judith Curry could probably have a calm and informative discussion together.Incidentally, while Judith Curry is sane, she should not be held responsible for some of her commenters, any more than you should be! (She has a very liberal commenting policy.)Dave
Her views can be found here:https://judithcurry.com/about/Maybe this sums it up:"These statements reflect a misunderstanding of the state of climate science and the extent to which we can blame adverse consequences such as extreme weather events on human caused climate change. The climate has always changed and will continue to change. Humans are adding carbon dioxide to the atmosphere, and carbon dioxide and other greenhouse gases have a warming effect on the climate. However, there is enduring uncertainty beyond these basic issues, and the most consequential aspects of climate science are the subject of vigorous scientific debate: whether the warming since 1950 has been dominated by human causes, and how the climate will evolve in the 21st century due to both natural and human causes. Societal uncertainties further cloud the issues as to whether warming is ‘dangerous’ and whether we can afford to radically reduce carbon dioxide emissions.""Oversimplification, claiming ‘settled science’ and ignoring uncertainties not only undercuts the political process and dialogue necessary for real solutions in a highly complex world, but acts to retards scientific progress. It’s time to recognize the complexity and wicked nature of the climate problem, so that we can have a more meaningful dialogue on how to address the complex challenges of climate variability and change."https://judithcurry.com/2014/09/21/an-unsettled-climate/
There appears to be a 60-year cycle in global surface temperatures not well-represented in the models (maybe due to fine-scale behavior of water vapor, maybe due to thermal flux in the barely monitored abyssal ocean, or both). For 30 years, the planet heats up steadily (both naturally and increasingly due to the GHG load), and then for the next 30 years, everything seems to shift into reverse (less dramatically as the GHG levels have risen, leading to a upwardly curving baseline).1880 to 1910. 1940 to 1970. 2000 to 2030?If this is a real phenomenon, 2030 to 2060 might be the time of reckoning.
Sabine,What is the point in discussing climate change issues? Seemingly you believe that the world is such that the laws of nature and randomness are causing you to say and do things. Seemingly you believe that you, in everything you say and do, are 100% the victim of laws of nature and randomness, so that there is nothing that you can say or do to alter or prevent your own outcomes, other people’s outcomes, or any climate outcomes. If that’s what you believe, then you may as well put your feet up and have a rest.If on the other hand, the world is such that people (i.e. a matter aspect of the world, as opposed to a law of nature and/or randomness aspect of the world) have genuine power over some aspects of their own outcomes (as well as laws of nature having power over most aspects of outcomes), then there might be some point in your discussing climate change issues.
Lorraine,"there is nothing that you can say or do to alter or prevent your own outcomes, other people’s outcomes, or any climate outcomes. If that’s what you believe, then you may as well put your feet up and have a rest."Your statement doesn't even make sense. Please think about it for a moment. You say things like "nothing I can do to prevent" or "alter" something which hasn't yet happened, but you don't explain what you mean by that. These are simply not meaningful phrases because there is no selection of futures to chose from.You can instead ask, did your actions have an influence on other people's decisions? Did the information you provide change somebody's mind about a particular topic? Would putting my feet up do the same? Probably not.Besides, (and I have said this before), arguing that the laws of nature should be so-and-so because you'd rather have free will is not a scientific argument. It's wishful thinking.
Sabine,The only causal factors in the world are laws of nature and randomness, according to physics. You (and everyone else) are not the cause of your own outcomes, any more than a ball rolling down an incline is the cause of its own outcomes. You (and everyone else) are enmeshed in a system where “your actions” and “your” words and climate change are merely the lawful and/or random outcomes of the system.So, you may as well put your feet up and have a rest because whatever you do, you can tell yourself that the laws of nature and randomness caused you to do it. And people may as well pollute the air and throw plastic bottles in the sea because whatever they do, they can rightfully tell themselves that the laws of nature and randomness caused them to do it. Laws of nature and randomness are the only causal factors in the world, if you believe physics: there are no other causes of outcomes.
Lorraine,You are using the word "cause" in a way that no one else does. There's a large amount of literature on that. I suggest you look it up. Besides that, I didn't say anything about "causes".
There is no free will, but we must PRETEND we have free will to prevent chaos.Despite what our limbic system screams at us, no one "deserves" negative consequences for unnecessarily destructive activities, but the properly proportioned THREAT of negative consequences reduces the likelihood of destructive activities."Putting your feet up" is a nihilistic response to having had too much to think, yet demonstrates a lack of imagination at how much suffering can result from a collective embrace of this perspective.Furthermore, I believe the Stoics are wrong to assume that suicide is always an option if things become intolerable. If the many-worlds interpretation of quantum wave collapse is correct, then once you are conscious, you will ALWAYS be conscious, with no guarantee of "pleasant" outcomes.Meet us halfway, Lorraine.
Sabine,According to physics, the only causes of outcomes are laws of nature and randomness. A cause is a “a person or thing that gives rise to an action, phenomenon, or condition” . No matter what you do or don’t do, no matter what you are or say or don’t say, or think or don’t think, your personal outcome is caused by the laws of nature and randomness. The climate change outcome is caused by laws of nature and randomness, according to physics.I wonder why you bother to discuss climate change issues. There is nothing you can do about climate change, according to physics, because there is nothing you can do about laws of nature and randomness. If you and other people continue to burn coal, then you and other people did that because the laws of nature and randomness caused you to do it; and the subsequent climate change outcomes will also be caused by the laws of nature and randomness.Whether you discuss climate change issues, or whether you put your feet up and have a rest, or whether you put some more coal on the fire, you can honestly and with a clear conscience tell yourself that the laws of nature and randomness caused you to do it. There is nothing you can do about the laws of nature and randomness.1. https://www.lexico.com/en/definition/cause (Oxford dictionaries)
Len,You can’t “pretend” your way out of climate change: you can never escape the laws of nature and randomness. You can’t pretend that you and other people are in any way responsible for climate change, because physics tells us that the laws of nature and randomness are responsible for ALL outcomes. Whatever you do, even if you “pretend”, it will be because the laws of nature and randomness caused you to do it. So, you can put some more coal on the fire with a clear conscience.
If there is no free will, than we cannot choose to pretend
Lorraine,Congrats, you found the definition. Now think about it.
“There is nothing you can do about the laws of nature and randomness” – yes, absolutely.But this gives you all the freedom you need, to do a lot.Neither a photon in a double slit nor a single atom nor “... radioactive material has a free will.” But a complex system like your brain has FAPP “free will”, because there are so many components involved. Each of course strictly obeying “the laws of nature and randomness”. It is your brain with your experience and your knowledge that can change the world. You are unique as well as your decisions.If your brain comes up with several equal alternatives and you cannot decide which way to go, take a pseudo random number generator to help - it still was you who generated the very alternatives to pick.And yes, of course, you are a weakly emergent entity from “the laws of nature and randomness”.
Sabine,According to the Oxford dictionary, a cause is a “a person or thing that gives rise to an action, phenomenon, or condition” . The point I was trying to make is that this definition, that people can have a genuine effect on outcomes in the world, conflicts with the views of physics. The views of physics are that persons and things are not actual causes; persons and things are caused; laws of nature and randomness are the only true causes, and they give rise to people, things, actions, phenomena, and conditions.The views of physics also conflict with the views of climate science. According to climate scientists, people have a genuine effect on outcomes in the world: people’s actions have caused climate change outcomes. But this view conflicts with the views of physics, which are that despite surface appearances, people can have no effect on outcomes in the world, so people cannot have contributed to climate change or act to avert climate change; it’s the laws of nature and randomness that are doing these things.Physics doesn’t have a theory which includes the aspects of the world that are very clearly displayed by people and living things. And in any case, there is no miracle that could transfer power over outcomes from laws to people; so people having genuine power over outcomes would represent a new physics theory of the nature of the world. There is no physics that can symbolically represent the creation of high-level plans of action to deal with e.g. climate change; these aspects of the world (creation of something new; high-level plans) must be a development of a so-far unrecognised fundamental aspect of the world; these aspects of the world cannot be a development of the aspect of the world that is representable by equations. And there is no physics that would make the implementation of these high-level plans of action possible: there is no physics that could connect up people’s high-level plans of action with the base-level numbers and variables that would be used to represent outcomes that are implemented.1. https://www.lexico.com/en/definition/cause (Oxford dictionaries)
Reimond,How does “this give you all the freedom you need”? What exactly is the physics of this “freedom”? What exactly is the physics of “you”?How does having “so many components” and being a “complex system” give you “free will”; what exactly is this “free will”?How does “your brain with your experience and your knowledge … change the world”? How did “your brain come up with several equal alternatives … to pick”? What is the physics of your brain coming up with high-level alternatives, choosing an alternative, and implementing a chosen alternative?What does “you are a weakly emergent entity” mean?
Lorraine,You clearly don't understand what I am saying. That's too bad but I currently have neither the time nor the patience for a discussion about free will. Also, it's off topic, so could you please avoid further comments on the this, thank you.
Lorraine said 'What exactly is the physics of “you”?' You are a complex emergent phenomena the details of which much is not known. In order to have discourse we have come up with a lot of concepts that when you carefully analyse it have proven very difficult to pin down. To figure out how they emerge in us from the laws of physics that analysis needs to be done first. When that is done we may be able to start discussing it. In the meantime people understand what is meant by human beings contributing to climate change, except you apparently. All our laws are either deterministic or random? Well lets look at the first law of QM (from Ballentine - QM a Modern Development). It says the outcomes of an observation are the eigenvalues of a Hermatian operator called the observations observable. There is a second law, but it basically follows from the first using Gleason's Theorem (and something called non-contextuality I will not go into here). That's basically all that's needed to develop the whole machinery of QM. Now where is the determinism or fundamental randomness there? It also is a non-trivial discussion figuring it out.
I'm surprised he didn't mention the methane problem. Or did he? Is that in the model yet? The rotting of the permafrost in the boreal regions?I have a story about my student days in the 1980s which I'll share (don't thank me, please :) I was killing time in the campus bookstore, a favorite activity, and came across a book on physical chemistry. The book looked pretty well done from a physics perspective. I've always loved chemistry and wondered what high-level chem students were reading. Well, I was looking through the problems at the back of one chapter and saw this one - a perfectly black sphere is covered with a layer of CO2 to a certain depth - how much does it heat up under constant illumination from a white light (sunlight) source? That was the moment when the entire global warming problem hit me like a ton of bricks. I remember getting into heated discussions with friends who were totally anti-nuclear ("No nukes!" was a fashionable mantra). I realized that only nuclear power offered a dense enough source of energy to replace fossil fuels, and also realized it would never happen in my lifetime because of fear and loathing of everything nuclear. Since then I have felt a little like the subject of Munch's famous painting, knowing what was coming, and powerless to do anything about it other than scream in silence. I stopped driving cars. I guess that helps.-drl
If you had a layer of CO2 which absorb the whole energy of some frequencies yet - and you increase the layer (in thickness or dense) - nothing changes.The absorption length of air with CO2 in the actual concentration is about ten kilometers. So the atmospheric CO2 absorbs all, what it can absorb, yet. So, what should change if the concentration rises?The climate problems actually are:- intensive agriculture, fertilization, damage of soil micro fauna and flora- land sealing- environmental pollution- overpopulation- excessive engineering progress and senseless consumption excited by the "public relation industrie"imho
weristdas,There is nothing "humble" about your opinion as doing as much as asking Google could have told you what's wrong about it. Read this, and please stop repeating false claims.
drl: I did not hear anything on methane either. As I understand it, it's a much smaller problem, not because it can't be modeled (as CO2 can), but because it has such a short half-life in the atmosphere (to first order the only place that matters).
@Jean I have the opposite impression, that methane truly represents the most existential threat of all, both from vast areas of boreal permafrost decay and from released methane clathrates in the ocean floor. CH4 is 20x as effective a greenhouse gas as CO2, and yes it has a relatively short half-life, but long enough to cause an enormous spike in temperature, enough to melt all the N-polar ice and even take a bite out of Antarctica, and to shut down the global ocean currents that define climate. Consequences are persistent zonal winds over N. America, turning it into another Australia, barren throughout the interior - among others. The world without the grain produced there is unsustainable. Mass starvation and world chaos would follow.-drl
@Javier this does not account for the enormous potential for methane production from rotting permafrost and release of ocean floor clathrates. And the effect is not ongoing, it is an impulse, a spike of some 15-30 years of extreme temperatures. This impulse is not well modeled, so simplistic graphs are of no use. And in the end, the CH4 breaks down into more CO2 and water vapor, using up atmospheric oxygen.https://www.reuters.com/investigates/special-report/climate-change-arctic-methane/-drl
@drl: yeah, I forgot about the clathrates.You, and many others, have surely come across this rule of thumb: pay attention to the product of probability and severity. For example, an asteroid impact may be exceedingly improbable, but its severity will be great, possibly existential. So it pays to spend some $$ on finding and tracking asteroids.I'm not sure how likely massive CH4 emissions from undersea clathrates are, nor their distributions (including by time), but even a quite modest chance multiplied by estimated severity means more research is more than justified. What if it turns out that the tipping point is now in the past (as it may well be for widespread ocean acidification) ... the oil-filled tank cars are heading for Lac Mégantic, there's no switch which can be thrown (there are no side tracks), no engine can get there in time, no air force is available to bomb them/the tracks in time ... the 47 folks are doomed.
Really good interview. Interesting subject, good interviewee, nice focus (different and more thorough than what I've come to expect from introductory videos in the subject), and very good questions. Really enjoyed it, thank you!Understandably out of scope for a video such as this, but if there any readers who may know, I'd be curious to read more about what is parameterized in a cloud model (e.g. emissitivity, humidity, etc), as well as what all (potential?) tipping points we have identified and their relative severity.I also love his spinning globe in the background.
Interesting to see you do this Sabine. He gave a few insights into the areas of climate science that need improvement, but with a lot of padding all around.
Did science get the ozone-hole (due to chlorofluorocarbons) wrong?
I have not read anything (reputable) to say that "science" got "the ozone hole wrong".May I ask, are you just guessing, or do you have something substantive in mind?
Scientists aren't popes ... they are capable of conditional error ;)In fact, assuming they are wrong and trying to invalidate their predictions is at the core of scientific progress.
The answer to this question is a very emphatic "No". They got it just right, and because chlorofluorocarbon emissions have been drastically reduced, the ozone hole has closed up significantly.https://www.newsweek.com/nasa-hole-earths-ozone-layer-finally-closing-humans-did-something-771922-drl
Sabine,I know next to nothing about climate science but there are some contradictory statements in this interview. Palmer admits that the current models, with a grid resolution of about 100Km, cannot possibly predict extreme events, like floods, drought, melting of glaciers, hurricanes and so on. Yet, he does not seem to doubt that an increase in temperature will increase the number/intensity of such events. Based on what? It might be the case that when the calculations will be done correctly, an increase of temperature will be found to be beneficial. I find his scientific integrity doubtful.
Andrei,Some things are predictable based on the current models and some things not. You can predict sea levels will rise which increases the risk of floods even though you are not able to predict exactly when and where a flood will happen or how long it will last. You can predict that hurricanes will get more intense, without being able to predict how many of them will happen. About the droughts, I'm not the right person to ask, but last time I looked they couldn't tell very well how long these would linger.All he's saying, really, is that the current models aren't good enough to tell you much detail but that the details matter for policy decisions. I don't see anything contradictory in that.
Andrei:If your house is on fire, and the authorities are telling you to get out, do you refuse to leave and say "You don't have any idea what you're talking about. You clearly don't understand fires because you can't tell me whether the living room or the kitchen is going to burn down first"?
PeterYour argument restricts the outcome to a (emotional) binary decision without presenting sufficient data to justify forcing that choice. For example what do you mean by 'house on fire'? Who are 'the authorities'? How are they qualified to say 'get out'?What you have done is to present a simplistic emotional argument in response to a comment on a highly complex topic. In doing so you have failed to address the essential point of the comment which appears to be the question of using non local models to predict local events.In general terms non local models will not give valid predictions of specific local events. However it may be possible to predict with greater or lesser confidence depending on the model the probability of those events occurring within a space and time boundary. These predictions may help to formulate a policy designed to reduce the frequency and/or severity of the event. The question of the validity the model and the confidence to placed in any prediction is at the heart of the technical side of the climate change debate. The policy formulated in response to those predictions is of course driven by political considerations.
Sabine,"You can predict that hurricanes will get more intense, without being able to predict how many of them will happen."Do you have some data in support to this? Is there a model that predicts the number of hurricanes that was confirmed by past data? Palmer does not mention anything about this. The same question applies to floods. Sure, if the level of the see rises the coastal regions will be submerged, but what I am interested about is the floods produced by heavy rains. Is there a model that was reasonably confirmed by past data predicting such rains as a result of increased temperature?
Andrei,I am sure you are able to ask Google as well as I can. It's no secret, go look it up. I have no interest in playing this game.
Peter,"If your house is on fire, and the authorities are telling you to get out, do you refuse to leave and say "You don't have any idea what you're talking about. You clearly don't understand fires because you can't tell me whether the living room or the kitchen is going to burn down first"?"1. I am not sure the "house" is on fire. True, each time a hurricane appears you see claims that it was cause by global warming. Yet, Dr. Palmer clearly said that such a statement cannot be supported by our current models. And certainly, hurricanes existed in the past as well. If you remove all those bogus claims the only "problem" we have is a slightly higher temperature (0.5 degree or so) than it was 100 years ago. 2. Palmer speaks about a "catastrophe" that would be caused by an increase of temperature of about 6 degrees. Is that really so? In the time of dinosaurs the carbon dioxide was 5 times the current amount, the global temperature was 6-12 degrees higher, yet all kinds of animals thrived. True there were no humans but I am sure humans could live in those conditions. I am curious how well the climate models we have are able to reproduce those conditions.3. There are positive aspects of an increased temperature. The plants grow faster and become more resilient to drought (some deserts already started to get green), huge regions will become productive (Siberia, Greenland, Canada), etc.
Peter:At the extreme risk of belaboring an analogy, what if you started running for the door, but the authorities said "No time! Run through the nearest plate glass window!"That is the more complicated argument about whether crashing the hydrocarbon economy immediately is a better outcome than shifting to renewables over a couple of generations.
Andrei, we can predict that a kettle will boil when turned on even though we cannot predict the formation and trajectory of every vapor bubble in it. This is a general pattern: we can predict coarse-grained effects, like the average number of hurricanes and their average intensity while not being able to predict every single event. This is basic probability and statistics.
Sabine,I've followed your advice and I've found this 2019 paper:Tropical Cyclones and Climate Change Assessment: Part II. Projected Response to Anthropogenic WarmingThomas Knutson1, Suzana J. Camargo2, Johnny C. L. Chan3, Kerry Emanuel4, Chang-Hoi Ho5, James Kossin6, Mrutyunjay Mohapatra7, Masaki Satoh8, Masato Sugi9, Kevin Walsh10, and Liguang Wu11DOI: 10.1175/BAMS-D-18-0194.1https://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-18-0194.1The conclusion is that for 2ºC of warming we should expect an increase of 14% in precipitations and 5% increase in the hurricane intensity. The costs of the Paris agreement are about 100 billion $ per year. The costs of this agreement by 2050 will be about 3 trillions. This is a huge amount of money to pay for a modest reduction in rain and wind speed 80 years into the future, don't you think?
Sergei,Please take a look at this paper:Tropical Cyclones and Climate Change Assessment: Part II. Projected Response to Anthropogenic Warminghttps://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-18-0194.1The "boiling kettle" is an increase of 14% of rains and 5% of hurricane intensity 80 years into the future. The costs of Paris agreement is about 3 trillion $.
Andrei: Hurricane Harvey cost $125 billion. There is no way to attribute a single hurricane to climate change, but climate change will substantially increase the number of disasters like this. $100 billion per year to implement the Paris agreement (which is quite possibly an overestimate) is ridiculously cheap.
Peter,The average number of strong hurricanes in the Atlantic basin is about 1.5 per year (see fig. 3 here: https://www.gfdl.noaa.gov/global-warming-and-hurricanes/)I do not know how many of them are globally and how many are comparable with Harvey. I estimate this number to be much smaller than 1, but let's say it's 1. Assuming the projected increase in intensity of 5% this gives you about 6 billion $ per year. So you invest now 100 billion $ per year to get 6 billion $ per year 80 years into the future. Very bad strategy, indeed!But even the 5% increase is highly questionable. Since the time we started to record hurricane data to this day there is no observed increase, no trend, even if the CO2 increased significantly. This means that there is no data you can use to adjust the computer models and, more importantly, there is no way to validate these models with hard data.So, all the data we actually have shows that the consequences of increased CO2 are good (increased plant growth, the planet gets greener), we have no reliable model to estimate the future consequences of the CO2 increase, yet you want to spend 3 trillion $ to keep the CO2 down. I don't see the point.
2,5 million years ago the North pole and the South pole were tropical areas. The latest ice-age is not over yet, the poles have not melted completely yet. Question is "Can we stop the process or even create a backreaction?
Remind me where humans had built cities and agricultural civilizations, two million years ago?
You don't get the point. Apparently the "human factor" is not the only one with regard to climate change. Maybe the human civilisation works like some kind of accelerator. Happily enough the Sahara is turning green again thanks to the increase of livesupporting CO2. By the way, answer my question if you can. One volcano eruption like the one of the Tambora (Sumbawa) is enough.
In the Mesozoic period Antarctica was connected to Africa, Australia and South America. Tectonic drift separated Africa in the Cretaceous. Australia separated about 40 million years ago and the Drake passage between Antarctica and South America opened up about 23 million years ago. Prior to this isolation Antarctica had a semi-tropical environment, but with this opening up there was then established a permanent ocean and atmospheric vortex that bottled extremely cold climate there. This was also facilitated by the end of the Miocene where CO_2 levels dropped from nearly 800ppm to 250ppm. The Pleistocene has seen episodes of glaciation called stades. We are currently in an interstadial period, which may be longer than most interstadials due to our CO_2 warming. There is evidence that human activity has had a CO_2 warming effect going back millenia, but where now we have put this in much higher gear with industry. These glacial epochs are with northern glacial episodes. Antarctica is permanently iced over, until some time in the distant future tectonic activity might shift that continent out of its polar isolation. The warming up of the climate is a sort of uncontrolled experiment. The short term consequences we now have estimates on, but the long term outcome is less known. This may throw the planetary climate out of this cycle of stades and into some other homeostasis. What that will look like is unknown. It may be conversely possible this will result in a boomerang where the release of warm fresh water on the ocean surface disrupts the ocean hydrological conveyor, which in the long run induces a tremendous glacial epoch. I think we have at this time no way of knowing what the long term outlook is.
Yes, we may know what we do (nonautonomously/exogenously), but what is/will be going on autonomously/endogenously is another question. Although, beware when it starts snowing and the snowing does not stop, it maybe the start of a new ice-age :-)
@marten: I am unfamiliar with the specifics of climate change before ~10kya. However, the change in global mean temperature, atmospheric CO2 (and many others?) since 1950, say, has been astonishing hasn't it? I mean, very few geological records have such fine time granularity, but other than at the Cretaceous-Tertiary boundary, is there any evidence for such a rapid change as is happening now?
marten:This rabbit hole is endless, if you insist on framing human contributions as either "exclusive" or "inconsequential".Since 1970, human GHG output has been more important for surface temperatures than natural variation. We can control that output, if nations in economic competition acknowledge the futility of the prisoners' dilemma of short-term victory at the expense of long-term prosperity.We can't move farmland or cities organically any faster than the generational timescale. If we stay on our current hydrocarbon path, we will likely need to engage in drastic reorganization of the global economy by mid-century. This will come with great risk of global warfare.It doesn't MATTER what the climate was like millions of years ago, because we didn't build our civilization in that climate. Rate-of-change is the issue, not the absolute range of survivability.
@ Len ArendsRate of change indeed. You at least do not deny the change.Your method to try and stop the acceleration endangers survivability. In Indonesia they are going to build a new capital on higher ground in Borneo. Very wise.
Very nice, very educational.
The basic concept from Hanson is pretty much on the mark. There he used Stephan-Boltzmann equation with empirical data on the trapping of CO_2 measured in a lab. Based on estimates of increased CO_2 output in his 1981 paper his predictions are spot-on. Of course these are global average estimates. To review, there are basic physical reasons for heat trapping. Carbon dioxide traps heat because the molecule has vibrational and rotational quantum modes that are excited by photons in the IR band. Consider the earliest lasers were IR lasers that used CO_2 as the lasing medium. Because of this IR photons are absorbed by CO_2 molecules and then re-emitted much more than O_2 and N_2 can, and this is the molecular basis for heat trapping.Tim Palmer makes a good point with the signal as the CO_2 forcing vs. fluctuations. As the average temperature increases there will be greater fluctuations. Einstein demonstrated with statistical mechanics the Einstein–Smoluchowski relation D = μkT for the dissipation and μ = particle motility or mobility. There is the fluctuation-dissipation theorem that tells us how a system with some frequency omega will have a fluctuation S(ω) = (kT/ω)Im F[χ], where xi is the susceptibility. So we should not be surprised to see that as average temperatures increase there is more uncertainty that we have to work with. This means that small scale influences have more potential global impact. This is in a sense the butterfly effect at work.I suspect at some point this will come to impact agriculture. The point when the grain bins leading down to the cupboards and refrigerators run out is where our butts will start to be kicked hard. I think the data shows something that early models did not capture, which is that the greatest warming has been in the poles. This means the temperature difference between northern temperate climate and the polar climate is lower. This temperature difference is what provides the kinetic energy, or force if one prefers to think that way, that drives the jet stream and polar vortex. We are seeing more of these odd cold fronts, the US has experienced one just this week, where extremely cold temperatures sweep south. The jet stream or polar vortex does not have the energy to bottle the polar cold air as well. Temperatures in the poles are still extremely cold, even with global warming, by comparisons to temperate regions, and when these spill south we get very cold weather. The scenario I suspect is that we may before long see in early summer extremely cold weather, say in May or June, that wipes out planted grain crops. If this starts to happen we are in really big trouble. This could seriously impact us before any sort of tipping point occurs where the climatic homeostasis shifts to some other attractor basin and Earth has a qualitatively different climate and ultimately biosphere.It is hard to know if we will get any real policy on this before it starts to really kick our butts. Consider that the most impressive physics experiment was conducted on July 16, 1945, with the first detonation of an atomic bomb. It took the best physics minds of the day 3 years to develop this. This technology was handed over to military and political people, who basically are of lesser minds. Now consider the nuclear launch codes are in the hands of Donald t'Rump who is the most stupid, venal and scurrilous president in US history. This is a sad indicator of the human prospect. There is an art project by Cordal https://imgur.com/gallery/WMTyj that gives a sad portrayal of the situation. I think it is not likely for us to see any clear or problem solving policy objective from American politicians before this matter really starts to painfully impact us. The landscape of climate basins of attraction or homestatic set points is probably the biggest unknown and objective of climate research. If this CO_2 forcing leads to the so called tipping point where the planetary climate is pushed out of its current basin of attraction we are then possibly toast.
FWIW, one topic not addressed was ocean acidification. While the impacts on agriculture will certainly be considerable (and may already be being felt), I feel ocean acidification may be a far bigger concern. Over-fishing is already severely disrupting food chains in the oceans; once acidification gets to the point where shellfish cannot easily form shells any more, wham!Of course, there will always be refugia, and some parts of the ocean will turn deadly acidic before others. But this is a slow-moving disaster, as it takes quite some time before the oceans and atmosphere reach equilibrium re CO2.
I see that as maybe a longer term issue with the implosion of ecosystems. Indeed this is problem, and it could be where Homo sapiens goes the way of the dodo bird. We are engineering the next mass extinction and so far we seem to be taking very minimal action to reverse course.The problem with agriculture I see as possibly coming within a few years. Maybe that will be the thing that dope-slaps humanity into action on this.
You wrote: "Consider that the most impressive physics experiment was conducted on July 16, 1945, with the first detonation of an atomic bomb. It took the best physics minds of the day 3 years to develop this. This technology was handed over to military and political people, who basically are of lesser minds. "I don't want to feel that I'm persecuting here as I have responded to a couple of your comments quite sharply already. But I don't really feel that I can't less this pass. The atomic bomb tests were *not* experiments - they were part of arms programme. To say that they were 'experiments' mischaracterises science which is the active search for understanding the universe and how it works. Nuclear weapons - to use a word that is unfashionable in these secular times - are an unmitigated evil. There is *no* moral justification for their use. Stephen Pinker wrote a book about the levels of endemic violence in so-called primitive societies; but in no way can blood feuds and the like can be compared to a situation where 80,000 people can be incinerated into radioactive dust at a press of a button. Moreover, Hannah Arendt in her book, *The Human Condition*, specifically writes:"The reason why it may be wise to distrust the political judgement of scientists qua scientists is not primarily their lack of 'character' - that they did not refuse to develop atomic bombs - or their naivete - in that they did not understand that once these weapons were developed that they would be the last to be consulted about their use.'
The test was an experiment, admittedly a part of an armaments development. The program was devised on the advise of Einstein and Szilard after Hahn and Meitner published a paper on the transmutation of uranium by fission. This was in the summer of 1939. The concern was the Nazi regime would develop a device capable of releasing large amounts of energy that would irrevocably tip the war in their favor. In the end the Uranverein in Germany never even got a reactor going, and by the time the US tested the bomb Germany had surrendered. Indeed tapes of Heisenberg et al reveal they were stupified that the Americans had done this.I do not particularly play Monday morning quarterbacking over the atomic bombing of Japan. I have though thought the second bombing on Nagasaki was completely unnecessary. The debate over whether Japan would have or have not surrendered without the A-bombing is inconclusive and the argument does nothing. Also given the absolute horror of World War II that killed 100 million people the atomic bombings were only .1% of that, though done in one bang. The firebombing of Tokyo in the prior April 1945 killed more civilians than the two atom bombs together. I will say in a bizarre sense maybe actually bombing cities with these small nuclear explosives may have provided the empirical test of just what they do to a city and its inhabitants. That might have served as a demotivator for pursing a nuclear war ever since.
A very informative talk and nice to see the following points:- a model where calculus’s “infinitesimal” dx is of the order of kilometers.- that for tipping points, i.e. nonlinear transitions the absolute values of temperature are relevant (breaking the above apparent “scale invariance”).- with every volcanic eruption (C02 + dust particles) temperature drops, since the particles block sunlight like clouds, hinting that for “sub grid parametrization ... most important are cloud processes”.Maybe you also talked about “Why stochastic climate models are more accurate than their deterministic counterparts” (here and also here).I also missed methane as a major component and melting permafrost as another tipping point, but nothing is perfect - not even doomsday ;-)
That was a very interesting and informative interview with professor Tim Palmer. His mention of more extreme regional weather patterns, was dramatically underscored by our recent cold wave in the eastern United States that shattered 145 year old records. For 3 or 4 days I’ve been waking up to temperatures of -12 to -8 Celcius, considerably below average for this time of year in southwest New Hampshire. Further north and west in Saranac Lake, New York it’s nearly -22 Celcius. I was surprised that he didn’t mention the well below average sunspot activity that has characterized this solar minimum cycle. That undoubtedly is a factor in our local weather, and probably elsewhere on the planet. Looking at Accuweather’s temperature chart for London they’ve had nearly 2 weeks of below average temps.In more than two decades of employment at the Woods Hole Oceanographic Institute the group I worked for till 2001, led by Dr. Erik Bock, investigated the wave structure of the ocean surface. Since this affects the transport of carbon dioxide across the air/sea interface it’s an important factor in climate modeling. Another group, from the Chemistry department, traveled with us on our sea voyages studying the surface chemistry of the ocean, as that too affects the movement of gases across the air/sea boundary. Tragically our Principle Investigator, Dr. Bock, died from injuries sustained in a bicycle accident in 2001. At that time he was in the planning phase for a research cruise in the North Sea, to be staged from a north German port. Woods Hole Oceanographic continues to be deeply involved in the influence of the oceans on climate change.
Informative and balanced article, thank you. For the record before I make my comment I need to say that I believe that there exists a risk that must be addressed. For me the salient factors are that the climatic change is unprecedentedly fast, changes are plausibly irreversible on meaningful human time scales (co_2 decay, melted ice sheets), and there is a demonstrable mechanism. If these are true as it seems then the risk cannot be ignored.But if hypothetically the risk on reasonable time scales did not exist I would not accept the models without empirical corroboration which could only occur outside of meaningful time scales,centuries or more. So given the risk the science is settled enough to act. Reasons for doubt about the model core model accuracy is the same as for any post-hoc theory particularly one that has so many parts.
Shiver me timbers, this cold snap continues unabated in the northeast USA. It dropped to -13 C. on my thermometer this AM, and -22.2 C in Saranac Lake, NY. I'm wondering whether the fact that this solar minimum is shaping up to possibly being the deepest in over 100 years is contributing to this unseasonable cold. So far there have been 242 days in 2019 without sunspots. With 44 days remaining to the year, 2019 could potentially exceed the 269 spotless days recorded during the last solar minimum in 2008.
I'm not trying to convince you of anything, David, but providing context for those who find your statements in any way persuasive.In our lifetimes, the Artic has warmed far more dramatically than the mid-latitudes. This has weakened the jet stream, which tends to isolate weather on either side of its course.A weak jet streams means more common polar vortexes traveling south.This has NOTHING to do with solar activity, which in the past 100+ years has barely contributed to climate variation.Volcanic activity is dramatic but short-lived. A couple of years after any major eruption, it's like it never happened.
That is it. These arctic cold fronts are due to this weakening jet stream and vortex that bottles up the cold. These events may start to occur more in later spring and early autumn. If so that will have dire impacts on agriculture. The most important and frequent question people ask is, "What's for dinner." In the future if that question can no longer be answered we are in a host of deep trouble.
Len, according to the chart on the webpage linked below, the Maunder and Dalton Minimums correlate quite nicely with the sunspot activity. So the temperature increase induced by human greenhouse gas emissions is presumably being modulated by solar activity, and luckily for us solar activity is in a downward trend. A funny thing I've noticed for decades, here in the northeast USA, is that really strong cold fronts often seem to roughly coincide with a full moon.https://www.whatsorb.com/news/global-warming-by-co2-or-cooling-by-a-grand-solar-minimum?gclid=Cj0KCQiAn8nuBRCzARIsAJcdIfOx9mRCZHk1QxUiZg7cG1gstbvuKsW3PoY4UsC6mDwqpHy9PZYB51kaAl2AEALw_wcB
Again, not for David's consumption but rather for the incidental reader:The solar (in)activity of the Little Ice Age was extreme, and ended in the early 19th Century. Nothing anywhere close to that variation has occurred in the modern era.
I enjoyed the interview. Perusing a few of the papers by Tim Palmer proved fruitful (i.e., I learned something). Learning: "the focus of operational numerical weather prediction has evolved from that of estimating the most likely evolution of weather to that of estimating probability distributions of future weather associated with inevitable uncertainties in both initial conditions and model equations." (Palmer's Paper: Primacy of Doubt, 2017). I also remain fascinated with Freeman Dyson: "I am saying that all predictions concerning climate are highly uncertain..." (2011, interview, independent.co.uk). Perhaps Palmer and Dyson could meet ?
Good to hear a scientific discussion on climate. It’s very rare now that climate is a political battle ground. Every newspaper has it’s agenda, for which climate is a weapon, to be deflected or wielded. Every opinion piece presents the science as complete or erroneous. Basic questioning of the science seems strange. Given a sun-sized hot-spot in a black sky, and a specified CO2 layer, working out equilibrium surface temp is an undergraduate heat-transfer assignment. The video did well, presenting the extreme difficulties in modelling of cloud, aerosol and terrain. Some things that would be interesting to learn about would include; • Would a warmer world be a wetter world, climate change might kill more people but increased rain may support a larger population. In the 1960s-80s Sahel droughts were associated with cooler periods. What happened to the “Greening of the Sahara”? Is it still considered a possible result of warming? • It used to be said that warming would effect higher latitudes the most. Tropics would see a much lower increase in temperature. What does change in mean latitudinal (?) temperature look like? • We are supposed to be near the very end of the current inter-glacial. Maybe the little ice-age was the first sign of the next glacial period. Is that all over now? No more ice-age, no more inter-glacials, only anthropocene? • Something that was repeated once in the video, was the warning that warming might make some of the earth uninhabitable (extremes of temperature and humidity making human life unsustainable). When in the Middle East I had to cope with a few fifty degree days, and it gets that hot I think, in parts of Pakistan and North Africa. So how far are we from a sustained heatwave, sixty degrees plus, lasting several days, and inflicting over a hundred million fatalities?
Hi SabineWonderfully informative as usual!One thing i didn’t understand. If non-linear events like ice sheet melting are irreversible then how did we get ice sheets after the last prehistorically warm period?Thank youCharles
Hi Charles,I think what he's saying is that if they melt off because of CO2 increase that doesn't mean that decreasing CO2 levels will give us back new ice sheets. There are presumably ways to get them back, like, you could try changing the axis of planet Earth, but I don't recommend it.
Charles:Google "Milankovitch cycles"
Charles: The polar ice caps have melted before (~160 million years ago), and then re-formed, but it takes a long time for that accumulation to happen. When we look at Antarctic ice cores, we have a climate record going back at least 800,000 years, and in spots we believe it can go back 1.5 million years, but those have not yet been cored (speaking from memory).By comparison, homo sapiens have been around, based on the oldest fossils found thus far, about 200,000 years.The melting of the icecaps would be irreversible for all practical purposes.
Someone in the comments above mentioned Judith Curry and how it would be interesting to interview her with Tim Palmer. This link is a little dated but brings up some points that would be interesting for Palmer to address. https://judithcurry.com/2015/12/17/climate-models-versus-climate-reality/amp/
The most important contribution to any subject that really matters is scientific INPUT. You might consider the following»The amplified Arctic warming in the recent decades may have been overestimated by CMIP5 models«doi: 10.1029/2019GL084385https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084385?af=R ..."The authors results indicate that CMIP5 GCMs EM overestimates the anthropogenically-induced secular warming rate since the mid-20th century against the observation and the overestimation aggravates with time, although the GCMs EM can simulate well the increase of the Arctic temperature over 1880-2017. This finding implies that the future Arctic warming could have been over-projected by the CMIP5 models..."..which leads to the question if it is already “enough” to be a physicist to seriously discuss or even “judge” climate science?
More to the point: did the media get climate change wrong? Media accounts, and the views of non-scientists concerned about climate change, seem to always be more extreme than what you read in the IPCC reports.Doomsday scenarios are as harmful as climate change denial, by Michael Mann
I think that kind of mischaracterises what the media is trying to do here which is to ring an alarm bell. It's supposed to get peoples attention.
What I want the media to do is tell me the truth, the whole truth, and nothing but the truth -- not decide for me what my priorities should be.
Nice video! What's that on the board at 18:50?
Navier-Stokes equation? I didn't ask, sorry. Guess I should have.
https://www.rsc.org/images/Arrhenius1896_tcm18-173546.pdfOn the Influence of Carbonic Acid in the Air upon the Temperature of the Ground Svante Arrhenius Philosophical Magazine and Journal of Science Series 5, Volume 41, April 1896, pages 237-2This photocopy was prepared by Robert A. Rohde for Global Warming Art (http://www.globalwarmingart.com/) from original printed material that is now in the public domain. Arrhenius’s paper is the first to quantify the contribution of carbon dioxide to the greenhouse effect (Sections I-IV) and to speculate about whether variations in the atmospheric concentration of carbon dioxide have contributed to long-term variations in climate (Section V). Throughout this paper, Arrhenius refers to carbon dioxide as “carbonic acid” in accordance with the convention at the time he was writing. Contrary to some misunderstandings, Arrhenius does not explicitly suggest in this paper that the burning of fossil fuels will cause global warming, though it is clear that he is aware that fossil fuels are a potentially significant source of carbon dioxide (page 270), and he does explicitly suggest this outcome in later work.
Nothing has brought home the warming of the planet via greenhouse gases as starkly as last night's special on TWC (The Weather Channel) titled "Meltdown". A married couple, who were researching the Helheim glacier in Greenland, were startled when a slab of the glacier, the size of lower Manhattan, broke loose with a thunderous roar. This enormous slab weighed an estimated 10 billion tons. The couple filmed the event, which can be looked up on the internet. The host of the program, Dave Malkoff, then toured an adjacent glacier with a researcher, who has been monitoring that particular glacier for years. Astonishingly, this glacier is receding at a phenomenal rate that is measurable by the day. Even more alarming is the rise in sea levels. At Hampton Roads, on the southern shore of Chesapeake Bay sea level has risen 14 inches. I spent part of a summer in 1976 at an apartment on this shoreline helping my brother in the renovation of a house nearby. I remember the terrain to be quite flat, so flooding could someday be a big issue there. Elsewhere on the globe coastal flooding is now a common occurrence.
David Schroeder,1. There is no significant global trend of ice surface. In the northern hemisphere it is receding but it increases in the southern one.2. The increase in see level is slow and in agreement with what we should expect given that we are departing from an ice age, regardless of the CO2 concentration.3. In the past it was the temperature increase that caused the increase in CO2, not the other way around.Do you have some reliable information about a significant trend in coastal flooding?
Andrei, This NOAA webpage addresses all the points that you made. It states that there has been a 3 to 9 fold increase in "nuisance flooding" in coastal regions.
I forgot to post the URL for the above post.https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level
David Schroeder,If you look at the first graph on the page you linked (Sea level since 1880) you may see that the trend is almost linear since 1880. There is a higher slope in the 2010-2015 interval, but a similar increase can be found in the 1895-1900 interval. Just compare this with CO2 evolution here:https://static.secure.website/wscfus/299177/7660724/noaa-ghgi-2017-co2-co2-eq.pngThe slope here registers a sharp increase between the 1880-1970 interval and the 1970-2020 one. So, the increase in see level is consistent with a slow, uniform warming as the result of the Milankovitch cycle induced warming, as you can see here:https://en.wikipedia.org/wiki/Milankovitch_cycles#/media/File:Vostok_420ky_4curves_insolation.jpgas oposed to a sudden increse associated with CO2 levels.In regards to that "nuisance flooding" I can see no relevant graphs showing a significant increase of them in the present. The Annapolis example cannot be extrapolated to global significance. Sure, it's a matter of logic that an increase see level will increase coastal floods, but there is no reason to believe that they have anything to do with CO2. The data we have is consistent with the expected evolution determined by Milankovitch cycles.
"Just compare this with CO2 evolution here:"And why the heck would anyone want to do that? Are you claiming that if CO2 causes temperature increase and temperature increase melts off ice -- which is, I feel the need to emphasize, a threshold effect -- then a graph for sea level rise should look like a graph for CO2 increase?
Sabine,1. It is not obvious that the increase of CO2 causes the temperature to increase. It is possible that the increase in temperature, caused by astronomical factors, determine an increase concentration of CO2 because of the lower solubility of CO2 in water at higher temperatures. Such an interpretation is supported by the fact that in the past there was a lag between the increase/decrease in temperature and the corresponding CO2 concentration, with the temperature changing first. See here:https://wattsupwiththat.com/2018/09/09/empirical-evidence-shows-temperature-increases-before-co2-increase-in-all-records/2. If the slope of see level vs time shows no change but the slope of CO2 concentration vs time shows a significant change the null hypothesis (the increased CO2 concentration is not the main driver of see level increase) seems to fit the data better, isn't it? If the see level increases today just as it did when no significant human-related CO2 emissions existed it is reasonable to conclude that the CO2 concentration is pretty much irrelevant.
That's right Andrei, it's not obvious. That's why you have to analyze the data using suitable models and statistical tools rather than just looking at a graph and saying "if I can't see it immediately it must be wrong".
I agree with you, but the problem is that we do not have such models that were validated. Even IPCC admits that. Those models are tuned to fit the data we have but there is little reason to trust them for the future. It's trivial to come up with an equation that fits any finite set of data points and in the future goes up or down, or remains constant. In fact, there is an infinite number of such functions. The only way to gain trust in such a model is for it to make a confirmed prediction. If you can point me to such a confirmation I stand corrected.
@Andrei: Milankovich cycles occur on time scales of 10^4 to 10^5 years. The obliquity of the Earth's axis and the apsidal precession or perihelion shift occur on 41k and 100k time periods. These have had an impact on climatic conditions in the past on these time scales. The current warming of Earth is happening over a time scale of decades. It is a usual rule of thumb that a process driven by an external force with some periodicity will be observed in that system as some similar periodicity, or maybe a small integral multiple or a half or quarter period according to Fourier summations. The matter of CO_2 in oceans is turning in a real problem on two fronts. The oceans may be approaching a saturation limit, which means the CO_2 in the atmosphere will less banked away. This mean temperatures may more rapidly increase. Secondly the decrease in ocean pH is a problem for coral ecosystems and invertebrate life that produces calcium carbonate shells. Please do not post Wattsupwiththat! Watt is a college drop out, he quit a degree in meteorology, who because a local TV weatherman and by virtue of this presents himself as an expert on climate issues. This is in line with a barrage of organizations that are well financed by fossil fuel industry and right winged organizations ( https://www.climaterealityproject.org/blog/climate-denial-machine-how-fossil-fuel-industry-blocks-climate-action ) and their follow-on actors such as Lobos Motl who have in addition extreme political agendas. While this is a very minority perspective with respect to science, it has a disproportionate political power and has crippled our ability to get any sort of grip on this problem.At one time I was a major exponent on this issue of climate change, but of late and particularly in this age of t'Rump and the triumph of lies I have take a bit of a que sera sera (what ever will be will be) attitude about things. In many ways I think George Carlin, look up his video on “Saving Planet Earth,” might have the right perspective on things, “Earth isn't going anywhere, we are! Pack your shit folks, we're going away.” It may well be that before the big OH SHITS report comes out and we are forced to deal with this it might be too late. Maybe in desperation we will attempt geo-engineering programs that may or may not work. Another species of sentient beings in the universe may check out of the Darwinian game. Maybe this is a solution to the Fermi paradox with alien beings and “Where are they?”
Andrei,"I agree with you, but the problem is that we do not have such models that were validated. Even IPCC admits that. Those models are tuned to fit the data we have but there is little reason to trust them for the future"That's wrong, Andrei. I have no idea where you take your knowledge from, but I suggest you find a better source of information. This may be a good starting point.
Sabine,"I have no idea where you take your knowledge from"What about the last IPCC report?Evaluation of Climate Modelshttps://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter09_FINAL.pdfTake a look at page 745:" In general, there is no direct means of translating quantitative measures of past performance into confident statements about fidelity of future climate projections."and:"However, there is still no universal strategy for weighting the projections from different models based on their historical performance."This is what I was saying. Let's see how well these models predicted the future. At page 824 we read:"An important consideration is that model performance can be evaluated only relative to past observations, taking into account natural internal variability."What? So we know that past performance does not imply reliability of future projections, yet only the past performance is used to evaluate the models. Great! But it gets even better:" Whereas weather and seasonal climate predictions can be regularly verified, climate projections spanning a century or more cannot. This is particularly the case as anthropogenic forcing is driving the climate system toward conditions not previously observed in the instrumental record, and it will always be a limitation."So, according to IPCC, not only those models were not validated, they do not even intend to do it. They claim the models are improved by quantifying their precision (deviation from the mean) but leaving accuracy aside (deviation from the true value).About the Hansen's predictions:1. It concerns CO2-temperature correlation. Such a correlation is beyond any doubt, has always been there regardless of human presence. I would be curious to see a comparison with the null hypothesis. What correlation should we expect in the absence of human-related emissions?2. It says nothing about hurricanes, see level, floods, etc. These are the phenomena that imply future risks and would presumably justify spending 3 trillions $, not a warmer climate per se.
Andrei,The statements you quote do not support your conclusion, that being that we do not have any climate model whose predictions we can trust. Frankly I think you don't understand what these quotes mean to begin with.Re Hansel: I just demonstrated that your above claim was simply wrong. In response you bring up whataboutism. I have no interest in playing such games.
Lawrence Crowell,"Milankovich cycles occur on time scales of 10^4 to 10^5 years."This does not mean that the temperature/CO2 are constant on shorter time scales. Take a look at this graph:https://www.ncdc.noaa.gov/global-warming/temperature-changeWe are now in a similar situation as we were about 120000 years ago. An increase in temperature/CO2 is normal. If the human emitted CO2 is so important we should see the temperature increase at a higher rate than it did in the past. Do you have any evidence that this is the case? How much temperature increase is due to the natural as oposed to human-related causes?"The matter of CO_2 in oceans is turning in a real problem on two fronts. The oceans may be approaching a saturation limit, which means the CO_2 in the atmosphere will less banked away. This mean temperatures may more rapidly increase."Again, the past records indicate that it is the temperature increase that determines an increase in CO2 not the other way around. What evidence do you have that now it is different? How fast is the observed increase in temperature as compared to past situations when there were no humans around?"Please do not post Wattsupwiththat!"I have linked above the same graph from NOAA, hopefully you are OK with that. You can clearly see that it is the temperature that changes first and CO2 follows.
Andrei,Please have a look at figure SPM.6 in the IPCC summary for policy makers. What is it that you cannot comprehend about this figure?
Sabine,"The statements you quote do not support your conclusion"Realy, let's see them again:"In general, there is no direct means of translating quantitative measures of past performance into confident statements about fidelity of future climate projections."and:"An important consideration is that model performance can be evaluated only relative to past observations, taking into account natural internal variability."So, past observations do not imply future performance, yet the models are evaluated only on the basis of past observation. It logically follows that we cannot trust the future predictions of those models (my conclusion). Please point the error in my reasoning. "Re Hansel: I just demonstrated that your above claim was simply wrong."No, you didn't. The discussion was about see level and hurricanes. Hansen's model just does not cover them. Even if his "scenario B" correctly describes CO2/temperature correlation this says nothing about hurricanes or floods. And in the absence of a comparison with the null hypothesis (temperature evolution for no human CO2 emissions) it does not prove that the predicted increase in temperature is related to humans, nor that stopping CO2 emissions will be of any help.
Andrei,You claimed that all climate models are non-predictive. I told you why that's obviously wrong. Now you are backpedalling.""An important consideration is that model performance can be evaluated only relative to past observations, taking into account natural internal variability."So, past observations do not imply future performance, yet the models are evaluated only on the basis of past observation. It logically follows that we cannot trust the future predictions of those models (my conclusion). Please point the error in my reasoning."The quote simply does not say what you think it says. It's a statement about the need to pay attention to internal variability. Performance to fit existing data (which, drums please, tends to be in the past) does of course not "imply" future performance because "imply" means 100% confidence. But it gives you a quantifiably high confidence (within errorbars) that the prediction is correct, in the same way that this works in all other disciplines of science.Also, fwiw, misinterpreting single sentences of a 1300 pages report is not good way to lead an argument in general.
Sabine,OK, let's focus on hurricane increase prediction. Tell me what are the error bars for that prediction.
Andrei,I don't know; not my area of research.
Andrei, you wrote "Again, the past records indicate that it is the temperature increase that determines an increase in CO2 not the other way around. What evidence do you have that now it is different? How fast is the observed increase in temperature as compared to past situations when there were no humans around?"I'm curious, what do past records show re the pH of the oceans? And how did atmospheric CO2 and oceanic pH vary, in this same past?
Jean Tate,I found this paper:Atmospheric carbon dioxide concentration over the past 60 million yearsPearson, Paul (2000), Nature. 406https://www.ldeo.columbia.edu/~dmcgee/Carbon/Syllabus_files/Pearson%20and%20Palmer%202000.pdfIt seems that the minimum pH was about 7.4 when CO2 concentration was 3500 ppm. In the last 25 million years CO2 concentration was between 150 and 450 ppm, while the ocean pH remained stable, between 8.0 and 8.3.
Thanks Andrei.The low oceanic pH and high atmospheric CO2 you refer to was during the Paleocene-Eocene Thermal Maximum, ~56 mya, right? If so, this is very, very bad news for us ... that period coincides with an ecological collapse in the oceans, recovery from which was very long (in human historical terms, i.e. more than a couple of generations).
JeanTate,Please take a look at the time/temperature graph here:https://www.climate.gov/news-features/features/models-and-fossils-face-over-one-hottest-periods-earths-historyWe see that the deep ocean temperature prior to PETM was about 8 C, while the present one is -7.5. The climate back then could not have been more different than the current one. There were no ice caps, the continents were in different positions, different oceanic currents, etc. So, the baseline is completely different, no similarity whatsoever.So, in that environment that looked like nothing we see today the temperature increased by 6 deg. due to some yet unknown cause. As a result, CO2 increased as well as it always happened. Some deep ocean creatures disappeared because of some unknown reason. Why is this bad news for us?I am all for a better understanding of marine creatures and I think we should invest much more in their research. We might actualy learn one day what happened to them and what can be done to prevent such an extinction, if possible at all. We could at least learn how to grow them in aquariums so that we can ensure those species will survive, no matter what. Diverting, say 1% of the Paris agreement money to this research could work wonders.
Thanks Andrei.I did look into the PETM a bit, and found that yes, the world then was very different from the world today.Another thing I found is that there seem to be very few times, at least since the Ediacaran, where atmospheric CO2 has increased so quickly as it has in the last decade or three. Of course, the geological record rarely has a time resolution as short as a century, much less a decade, so some rapid rises may be invisible.The ocean acidification in the next few decades will drive many species to extinction, however refugia certainly exist, so the numbers of families which go extinct is likely to be quite small. The catastrophe for us is the disappearance of a great deal of seafood.
JeanTate,"The ocean acidification in the next few decades will drive many species to extinction"What evidence do you have for this claim?
A very interesting video. I can't imagine how frustrating it will be for you to go through the comments. I was personally captured by that beautiful globe in the background.
Excellent interview. I am very gladdened to see a balanced discussion devoid of obvious skeptic and/or alarmist biases. Its very annoying having to explain basic science and computational modelling to just about anyone I speak to about it. Hardly anyone, for example, understands is not CO2, Methane, Ozone etc that directly affects climate change, its water vapor: https://www.acs.org/content/acs/en/climatescience/climatesciencenarratives/its-water-vapor-not-the-co2.html. I always mention that to anyone that asks my view on climate change as well as the also excellent article you wrote about the computational power required to better predict the climate future.
The interview emphasizes that estimating cloud cover is problematic in the models. It does not mention what is perhaps the most important uncertainty - the amount of water vapor. Water vapor is a vastly more potent greenhouse gas then CO2, but the models are unable to incorporate it, and essentially assume it stays at equilibrium. If that is off by a little bit, the models are off by a large amount. A second huge uncertainty, given brief mention, is the time lag between CO2 changes and their impact on temperature. This lag spreads out over decades, but just how many is uncertain. The longer the lag, the greater AGW effect. The simple, basic physics of global warming is clear - the increased re-radiation of low frequency waves down to earth due to CO2, etc. - so global warming is inevitable. But I don't think the models add much to that. Given the lack of information about key parameters, there is a better way to go - look at the past association between CO2 and temperature, through regression analysis. I have attempted that, and I find that the models have substantially underestimated the impact of CO2 growth, and that CO2 growth at any one period affects temperature over a sizeable time delay, some 10 to 40 years.
It's probably a subjective observation, but it almost seems that we had more snow back in the late 50's to early 60's, when my brother's and I would fan out across town to make money shoveling out people's driveways. I was full grown by the winter of 59/60, and remember shoveling snow in Teaneck, NJ that nearly reached my waist, either that winter, or one of the several following winters. There would have been considerably lower levels of man-made greenhouse gases in the atmosphere 60 years ago than today, which could have tipped the temperature balance in favor of a snowstorm versus a rainstorm. Looking out my computer room window at 16 inches of fresh snow and a temperature of almost -22 Celcius (-7F) in nearby Keene, NH, fortunately the apocalyptic vision, (from two decades ago), of a snow free United States never materialized.
With today's high in the low 60's in Keene, NH, and tomorrow's temp. predicted in the same range, I was hoping that this presaged a warm winter right into Spring. Such hopes were dashed when I checked the long range forecast, that shows brutal cold returning for the next 5 or 6 weeks, with lots of single digit (Fahrenheit) lows. Nonetheless, we have been experiencing steadily warmer winters on average, especially in recent years, according to our local weather forecasters.
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