There is way too much bullshit on both sides of this debate.
The scientific consensus is real if the question is, “Is man-made CO2 emission causing an increase in warming?”. Not only is there a strong consensus, but the science really isn’t that hard to understand. CO2 is a greenhouse gas - that can be shown theoretically and experimentally with ease. CO2 concentrations in the atmosphere have been increasing - that can be shown with direct measurement fairly trivially as these things go. Therefore, it stands to reason that man-made CO2 has changed the atmospheric balance in a way that should cause additional heating.
For almost all scientists (including many on the so-called ‘denier’ side), these facts are uncontroversial.
But then we get to much more difficult questions, such as what effect this additional climate forcing will have on the climate 50 years from now, how much more CO2 humanity will continue to pump into the air over that period, how much damage will be caused both to the ecosystem and the economy over time, what kind of technology will be developed over that time, etc. These questions have varying amounts of consensus behind them, but there is still a lot of room for debate on these issues.
We are dealing now with the long-term movement and interaction between multiple complex adaptive systems, and our history of trying to predict them is dismal. The climate argument requires that we project things like economic growth and demand for energy 50 years into the future, when in reality our best economists do no better than chance in predicting economic growth even 2 or 3 years into the future. The same goes for the climate, for human population moves and growth, technological advancement, etc. There is no consensus on any of these issues.
Then once we get beyond that, there is the question of what can or should be done about it. We’ve tried biofuels, and made the problem worse. The signatories of the Kyoto treaty failed to live up to their promises. Cap and Trade systems have proven to be relatively ineffective and easily gamed to enrich powerful interests. Attempts to get China, India and Russia to cooperate with global climate policies have failed.
Studies which have attempted to calculate the cost/benefit of direct action against climate change have had to use extreme scenarios for damages and very generous scenarios for the costs of prevention policies to come up with numbers that make the case for action.
So yes, there is a strong scientific consensus that man is in part responsible for warming, but that’s only the first of many questions that have to be answered before major action is justified. People on the AGW advocacy side want to translate that into a scientific consensus for every policy change they want to make, while people on the right want to deny that there is any consensus at all. Both of them are wrong.
Ok, then we can disregard the rest, sorry but not looking at the overwhelming evidence and the majority of scientific groups **and economists **that also looked at the issue it is really silly to continue to pretend that both sides are wrong.
As for the “Attempts to get China, India and Russia to cooperate with global climate policies have failed.” this is grossly ignoring what is being negotiated already.
Yeah, and you can get economists to produce very authoritative-sounding forecasts for where the economy will be in five or ten years - the Congressional Budget Office does this every year. You can get any number of experts to make very comprehensive predictions about the future movement of the stock market, the population, the ecology, and they get dutifully reported in the newspapers as fact. Which doesn’t change the fact that these types of projections and predictions utterly fail, over and over again. The mystery is why we keep listening to them.
I suggest you pick up Nate Silver’s “The Signal and the Noise”, which does an excellent job of punching holes in expert predictions.
Complex systems are not predictable. They are extremely sensitive to initial conditions. They adapt and feed back on themselves. They are dominated not by fixed laws and curves, but by shocks and random noise. You can’t predict the future by looking at their past behavior, because they adapt.
You already recommended that in the past, there has been no evidence really that the experts are wrong on this issue.
And this also grossly ignores that in this issue we are looking at different scenarios, so far the evidence points at action in the emissions issue is taking place in Europe, the USA and other places, but not at the levels that are needed to avoid scenarios that will be more expensive.
And then there is the problem one can see when several of those conditions are getting worse than expected.
I just want to ask these questions, to cut through to the core of the issue:
What is the “policy change” that the IPCC wants to make, since they are, under the terms of their charter, non-prescriptive and policy-neutral?
Do you doubt the veracity of the IPCC meta-analysis of the scientific literature?
Do you also doubt the supportive conclusions and recommendations of every national science academy of the major countries on earth that we are facing a serious problem and that urgent action is necessary? Do you consider major national and international science organizations to be “AGW advocates” trying to force nefarious and unwarranted policy changes? Do you realize how utterly ridiculous this allegation is?
I suggest you acquaint yourself with “Merchants of Doubt”, which is a movie, a book, and also typifies a general concept of how self-serving vested interests protect themselves – and which is an excellent description of the astounding degree to which AGW denialists have poisoned the debate. Santorum’s idiotic claim was just one miniscule example of a vast infestation of self-serving lies on this subject that presently dominate the Internet and right-wing media.
That’s a meaningless, facile non-statement that begins with an incorrect premise. It’s essentially saying “hey, it’s complicated, so maybe it will all turn out alright, who knows?” which is nothing short of dangerously irresponsible as a response to more than half a century of science and modeling and the well-established consensus in national and international scientific organizations that go far, far beyond your simplistic description of the immediate first-order warming effects of GHGs.
The problem with the premise that complex adaptive systems are “unpredictable” is that any system, CAS or otherwise, will be unbalanced in a predictable direction in the presence of a sufficient external forcing acting consistently over a sufficiently long period of time, and the real scientific consensus is that this is exactly what’s happening to the climate, with resulting instabilities and a vast series of undesirable consequences. That those consequences are not necessarily predictable in time or geographic area is immaterial to the argument; indeed, some of them are already worse than predicted. In that context the CAS argument becomes a meaningless facile diversion.
I didn’t say anything about the IPCC wanting to make policy changes. I was talking about the AGW movement in general, which definitely is pushing for policy changes.
Nope. Because that’s where I got my information about the lack of scientific consensus on many of these issues.
For example, the biggest ‘positive feedback’ posited for large values of climate sensitivity is water vapor. What’s the consensus on what has actually happened with water vapor?
The effect of cloud cover on global warming is one of the major uncertainties called out in AR5. But how about measuring the change in cloud coverage?
Lots of people have been claiming that the California drought is due to global warming. What’s the consensus of scientists on that?
So not only is confidence low on these trends, but the scientific evidence suggests that global warming should be having the *opposite *effect of drought in North America.
How about the accuracy of the models?
The rest of the section on modelling talks a lot about how much the models have improved since AR4. But I recall that long before AR4 we were being told that the models were extremely accurate. Huh.
But what we really want to know is the consensus of scientists when it comes to the long-term predictions of climate change due to CO2 emissions. What does the IPCC have to say about that?
[Quote=IPCC AR5]
Global mean temperatures will continue to rise over the 21st century if greenhouse gas (GHG) emissions continue unabated. Under the assumptions of the concentration-driven RCPs, global mean surface temperatures for 2081–2100, relative to 1986–2005 will likely be in the 5 to 95% range of the CMIP5 models; 0.3°C to 1.7°C (RCP2.6), 1.1°C to 2.6°C (RCP4.5), 1.4°C to 3.1°C (RCP6.0), 2.6°C to 4.8°C (RCP8.5). Global temperatures averaged over the period 2081–2100 are projected to likely exceed 1.5°C above 1850-1900 for RCP4.5, RCP6.0 and RCP8.5 (high confidence), are likely to exceed 2°C above 1850-1900 for RCP6.0 and RCP8.5 (high confidence) and are more
likely than not to exceed 2°C for RCP4.5 (medium confidence). Temperature change above 2°C under RCP2.6 is unlikely (medium confidence). Warming above 4°C by 2081–2100 is unlikely in all RCPs (high confidence) except for RCP8.5, where it is about as likely as not (medium confidence). {12.4.1, Tables 12.2, 12.3, Figures 12.5, 12.8}
[/quote]
Now, a word about these scenarios. They aren’t science. The IPCC calls them ‘storylines’.
For example:
This is little more than a bunch of people getting together and coming up with fictional-yet-plausible scenarios for what might happen. Out of these scenarios comes some estimates of what kind of economic growth and CO2 emissions might occur. But no one really has a damned clue. For instance, just months after this was published the middle east began to collapse and millions of people are streaming into Europe. The 2007 report failed to model or predict the financial collapse that was just months away, and a subsequent major reduction in CO2 emissions. That report also missed the fracking revolution which caused the U.S.'s CO2 emissions drop below the Kyoto threshold all on their own without any agreement being signed at all.
Seriously - we’re talking about models trying to project what the world will look like 70-85 years from now. If you put the best minds of 1930 together and asked them to predict what 2015 looked like, do you think they would have been close? Even in the ballpark? If you think so, I suggest you go look at the World’s fair from back then and see what the best minds thought the future would look like.
The other day I was in our local "Space and Science’ center, looking through the environmental exhibits. One of them was on peak oil, and made the claim that the majority of scientists believe that we have either reached ‘peak oil’ or will have reached it soon. And yet, I don’t see a ‘peak oil’ scenario in the IPCC scenarios. What if we HAVE hit peak oil, and petroleum prices will soon skyrocket? What will that do to global warming? Or is ‘peak oil’ only yesterday’s boogeyman now that we’ve got global warming to scare us?
The idea of predicting the effect of new, yet-undiscovered technology on a future world 75 years from now is ridiculous. Anyone trying to do that in 1930 would have missed the rise of large-scale commercial aviation, nuclear power, the interstate highway system, the vast array of new appliances and electronics that drove up domestic energy requirements, etc. If those same people tried to do it in 1960 they would have missed the semiconductor revolution, the rise of computers, solar power, satellite communications, etc. If they tried to do it in 1980 they would have missed the fall of the Soviet Union, the rise of China due to a shift to capitalism, the internet, cell phones, and most importantly, the impending global demographic collapse that no one saw coming but which changed the world’s future dramatically.
But I’m sure THIS time they’ve got it nailed.
And then, even taking these scenarios at face value and assuming that one of them is largely correct, AND that the output of the scenario can be reasonably fed into a model, AND that the model itself does a good job of predicting the future, the IPCC makes some rather modest projections. RCP 4.5 is the median model here, and the prediction is for temperatures to increase between 1.4°C to 3.1°C, relative to the temperatures measured between 1986–2005, or somewhat lower relative to today’s temperature if you believe the earth has been warming since 1986-2005.
Now, this is a spread wide enough that on the low end it is scarcely more than what you would expect from natural forcing alone, to ‘somewhat worrisome but not catastrophic’. And even with this wide range, they’re only willing to assign a ‘likely’ probability to it.
All of the scenarios that contain temperature swings of the magnitude climate alarmists say are going to happen are assigned an ‘unlikely’ probability. In other words, they’re the extreme ends of the bell curve. And all this is still based on a lot of very shaky assumptions.
Should I read the science, or just listen to the political statements of science organizations? And how do they justify ‘urgent action’ when A) the IPCC says the likely scenario isn’t going to be that bad, and B) they have no idea of what to do that will have any impact. If I went to a client and said, You MUST take urgent action! And they said, “Okay, go do it!” My reply had better not be, “Huh? I have no idea what should be done. I just know that whatever it is, you must do it NOW!”
One of the annoying hidden assumptions of the ‘Act now!’ crowd is that they never want to put any numbers or predictions to what will happen to CO2 output under a specific policy they propose. They have no answers to real, hard questions about the efficacy of what it is they want to do, or the cost.
For example, do you know what the Integrated Assessment Models use for their prediction of CO2 output? A very simple equation that says that CO2 output is a direct function of economic growth. And in the past, that’s been true. But then the people who want to DO SOMETHING NOW say we can make dramatic cuts in CO2 without any reduction in GDP. Or if they’re really brazen, they’ll claim that we’ll actually grow GDP while cutting because of <hand wave>‘Green Jobs!’<'/hand wave>
Guess what? You can’t have it both ways. If CO2 is directly correlated with GDP, then our efforts to curb CO2 must have a severe impact on global GDP.
The other thing they do that’s very annoying is they tell us the horrors that await unless we take action, on the hidden assumption that taking action will prevent the horrors. What we should really be talking about is exactly how much CO2 will be reduced by those actions, and how much effect that will have on the damages they are predicting. If we’re heading for a world that’s 4.1 degrees hotter without taking action, but adding on crippling carbon taxes will result in a world that’s only 3.9 degrees warmer, then we’ve only bought .2 degrees of harm mitigation. Is that worth it?
This is where we cannot separate the science from the politics. Of COURSE you think it’s worth it if you believe that carbon taxes are an intrinsic good, as I believe most liberals (and therefore most scientists) do. OF COURSE you think that global action is a good thing to do if you believe that strengthening global institutions like the UN is an intrinsic good, as most liberals do.
But if you don’t believe those things, you’re going to set the bar a lot higher. So now we have to have a political debate about nationalism vs internationalism, taxes vs individual control of money, yada yada. Pretending that this divide doesn’t exist and it’s all about the science is silly. But then, it’s hard to convince your opponents of the value of higher taxes or international governance. Much better to frame the debate in terms of SCIENCE vs DENIERS!
Do you believe that anti-AGW ‘deniers’ are all funded by the evil petroleum industry? Do you know how utterly ridiculous that allegation is?
I don’t think there’s anything so ridiculous as an international cabal to use AGW as a tool to help the rise of international socialism or anything like that. I do think that if you are a person that is biased towards believing that higher taxes on industry are a good thing and that international institutions should be strengthened, you’re unlikely to count those as costs in your assessments.
Oops. We’re back to politics now.
Do you know the origin of the ‘precautionary principle’? It comes from the study of complex systems, which led environmentalists to the conclusion that we muck with the environment at our peril, because it is impossible to predict the effect of our interventions on a complex adaptive system. If I were an evil henchman in charge of an oil company, I guess I might say, "That’s a facile non-statement. It’s essentially saying, “Hey, who knows? Maybe it will all go to hell.” Which is nothing short of dangerously irresponsible given the half-century of knowledge we have built up on the effect of mining in sensitive ecological areas.
Environmentalists are very quick to claim that complex systems cannot be predicted and therefore we should err on the side of leaving them alone. But when it comes to AGW, they’re perfectly happy to believe that we can predict not only what will happen to the ecosystem, but to the many other complex systems that are constantly mutating and adapting as we go into the future.
And of course, most leftists who are totally on board with the precautionary principle in nature are perfectly willing to constantly muck about with and try to direct human society and economies, where the same logic should apply - but doesn’t.
And therefore if your argument is, “We should apply the precautionary principle and cut CO2 emissions because we have no idea what they will do to our climate, and it might not be good”, you’d be on more solid ground. But this is incompatible with the idea that we can intelligently predict and model what will actually happen.
If they aren’t predictable, how do you know they are undesirable? The IPCC’s own assessment in AR4 said that warming under 2.5 degrees would ‘likely’ be a net economic benefit to the planet. Sure, I can point to lots of undesirable potential consequences. But I can also point to some potential good consequences, such as the opening of the northwest passage, warmer winter nights in cold climates, possibly more rainfall in drought regions, stimulation of additional plant growth, etc.
Look, I’m not trying to deny the existence of global warming, or even to deny that it’s likely to cause some bad stuff to happen. I’m simply pointing out that when you look at the entire issue from front to back, it’s a hell of a lot more complicated than, “97% of scientists agree with ME, so SHUT UP you denier scum and let me raise those taxes on carbon!”
I’ve been resisting posting in yet another waste of time topic (because facts won’t change anyone’s mind on this issue), but damn Sam, that was good post, and I know how much time and effort goes into those sort of things. Thanks.
Of course. In fact, it’s one of the most complicated scientific problems mankind has ever tackled, understanding the entire global climate/weather system, and trying to model it, and be able to predict future changes. It’s massive, and as complicated as anything we have ever faced.
The political issues are actually simpler, especially for the simple minded. “CO2 increase deadly bad and a crisis, we must act now.”
For those sure of the problem, the only thing is to provide a solution. Of course if it really is as simple as “burning fuel bad, must stop”, then it will be solved just like mankind has solved the other big problems that are worldwide.
And of course the pickings are not good so you are left to think that Sam is helping, in reality he already said that guys like you are wrong:
[QUOTE=Sam Stone]
So yes, there is a strong scientific consensus that man is in part responsible for warming, but that’s only the first of many questions that have to be answered before major action is justified.
[/QUOTE]
Essentially you are talking about items that made the situation worse, not sure what that does demonstrates, except that then the worse scenarios are more likely in the future.
And it is clear that you did not read what Michael Man reported about the probabilities we are facing.
The reality is that the numbers that count are not going down (CO2 concentrations), so once again, what we are observing now is warming already caused by humans, and the logic does not change: numbers like those ones need to be reduced so then one could could talk about better scenarios for the future.
Nuclear power didn’t make it worse. Neither did cell phones or the internet. The Internet has replaced an awful lot of travel with teleconferencing, for example.
We are on the verge of potential transformative technologies being right on the horizon. Virtual reality might make it possible to replace a lot of transportation energy with bits. Nanotechnology, 3D printing, and other materials breakthroughs are going to lower the cost and energy requirements of structures. If SpaceX manages to soft-land its rockets, it will cut the cost of space access by 90%, which may make space solar power, space manufacturing, and resource capture from asteroids financially feasible.
On the energy side, we’re still making improvements in solar, and there are a number of technological breakthroughs in nuclear power that could change everything. Small Modular thorium reactors could allow the 3rd world to leapfrog over the fossil fuel phase of economic growth.
And these are just a few of the things we already know are coming, but don’t yet know what effect they’ll have. Then there are the unknown unknowns - the technologies we can’t predict because they haven’t even been discovered yet. But sure as rain there will be many of them, and because we have no idea as to their nature we have no way to predict how the future will be changed by them.
Have you read “The Black Swan”? In it, Nassim Taleb talks about how the notion of linear ‘progress’ is an illusion. In reality, our economy moves forward in a series of steady states punctuated by ‘black swan’ events that cause quantum jumps. 9/11 was a Black Swan. The 2007 financial crisis was a Black Swan. The discovery of atomic energy was a Black Swan. The internet was a Black Swan. It’s a compelling argument, and it makes predicting the future even less likely because by their nature Black Swans are completely unknowable before the fact.
Don’t care. I’m tired of the shell game of demanding that the IPCC be the authoritative source - until it doesn’t support the argument in question, at which point it is to be ignored in favor of some other dire prediction. The only way to have a rational debate on this subject is to anchor it around an authoritative source of information - that happens to be the IPCC, and since AR5 came out it’s also up to date. I see no reason to ignore it in favor of some individual scientist’s predictions.
It is important to separate the short-term effects from the long-term effects. In the short term I think you’d find that we’re very much in agreement over CO2 and what it’s doing to the atmosphere. But the climate is a very complex system, and it interacts closely with the living ecosystem, another complex system. And also with human society.
We are still learning a lot about how they work together. For example, until recently it was thought that most of the CO2 sequestration from plant life came from arboreal forests. That makes it a positive feedback, because as the earth warms the arboreal forests would shrink. Tropical rainforests were thought be a minor player here. But recent data shows the opposite - that the rainforests are a bigger sink of carbon than arboreal forests. That changes a large positive feedback into a large negative one, as rainforest growth would increase on a warmer planet.
There may be other unknown mechanisms that will work in the opposite direction, so I’m not claiming that things are better than they appear to be - just a lot less certain than we want to believe.
And I can believe this even if many august bodies of thought believe they can, because we can see that kind of failure all over the place. The IMF still pretends it can model economies and tweak them, despite their dismal track record. There are still large investment firms making a living convincing investors that they can predict market moves, when we’ve known for a long time that they can’t. The CBO still does 10 year projections despite the history of them being no better than chance. Economists still draw curves to predict the result of policy changes, and policy makers follow them, despite their results being no better than chance.
We have a powerful urge to predict and control the future - an urge that greatly outstrips our ability to actually do it.
Thank you very much! I appreciate that. But I do think you and I are coming from slightly different places. I do believe that the ‘science is settled’ on whether warming is occurring and whether man is playing a part in that. The evidence seems pretty overwhelming to me. So I’ve got to go where the science takes me. I just think the science starts to get a lot less certain and the policy implications even more so once you get past that basic understanding.
This is all nice, but then it has nothing to do with trusting science, but it does point to the possibility that things will get better, but we should not trust only that our wishes will come true.
If that was the way we actually did deal with big issues we would never had controlled contamination in our rivers.
As for not caring about what scientists and experts tell us, that was Michael Mann the one that you dismissed. I will check his advise more than I will check your uneducated opinion.
No doubt. While I am skeptical about a lot of the nonsense and absurd claims made by many many parties, I act as if Anthropogenic warming is a fact, to the point I have done radical crap like making my roof white, rather than dark. Most of the things that reduce my CO2 output I already do, because they save money, decrease pollution and are healthy. (white roof, lower electric bill, much cooler roof)
That, and because I pay for nuclear power instead of coal or natural gas, my effect on the atmosphere is positive. This however, means almost nothing in the larger scheme of things, because it literally has no effect on the rest of the world.
This speaks to the topic. If that is so, you should be able to explain it, so that anyone can understand it.
Again, if so, explaining it in a manner that an interested person can understand should be easy.
That may be true, but is another topic. Speaking of
While I disagree in regards to very complicated and advanced sciences, the example of AGW certainly should be transparent, and explained in ways that anybody can follow along.
Indeed, and it because this isn’t done, which is absurd really, many people do find it sketchy, especially the dire doom and gloom sort of claims.
At the risk of catching flack for riding the same horse into the topic, this point, ==>the argument that basic global warming theory should be easy to explain, and it should be the same no matter who is explaining it, is a solid one.
A major theory should never be a mystery to the public. Especially when it is the victim of attacks from religious or financial vested interest.
The problem I see here is that this is not really a discussion about what to do, or about the economics of it, but about trusting the scientific basis of why we should not dump all that CO2 into the atmosphere.
Clearly Sam can not help to go back to discuss the science even if he claims that that should not be done. I can see that there is still a lot of poisoned sources of information that he is using still.
BTW that “Black swan” about the financial disaster of 2007 is related to what we are talking about in the sense that in a downturn the human emissions do decrease, but not much to solve the issue, but the efforts of controlling emissions now are likely to be working and they are not causing an economic disaster as many on the right keep on telling us.
The point here is that a lot of the doubts from Sam seem to be related to us not being able to predict what we will do regarding emissions, but that is not what I have seen is the issue, what I see is that was predicted and now being observed is based on what it has already been emitted and what it is likely to be emitted in the near future.
The basic science here is pretty easy to understand.
First, it’s certain that CO2 is a greenhouse gas. If you add CO2 to an atmospheric mix and apply solar energy, it will warm up more than that same mix without the addition of the CO2. This is uncontroversial, basic science. Do you agree?
Second, it’s also uncontroversial that we are pumping quite a lot of CO2 into the atmosphere. We have pretty good measurement techniques and have a pretty good understanding of how much CO2 is in the atmosphere, and how much it’s increased over the past few decades. These are hard, direct measurements - not interpretations, or models, or extrapolations.
Third, we don’t know of any other source of CO2 that could be causing this increase, and it’s virtually certain that man is certainly causing the majority of it.
From those basic facts we can assume that the atmosphere is trapping more energy than it would it we weren’t pumping CO2 into it, and therefore we would expect the Earth to be heated more than if we hadn’t added any CO2 at all.
Those are the arguments for the basic consensus proposition that the Earth is warming and we’re helping to cause it. What are the arguments against? Well, the most common one is that there has been little measurable warming for more than a decade. Does that prove anything? Nope. It doesn’t really matter if there has been no warming for the last decade, as there are other cycles that affect the global temperature. Over a period of a decade or even two or three, natural variation can easily swamp the warming ‘signal’. In fact, if you look at this temperature plot of the last 100 years, is there any doubt that the Earth has been warming? And yet, note that there was a drop in temperature around 1945, and the temperature didn’t recover to pre-1945 levels until almost 1980. That means that anyone who chose 1945 as their start date could say in 1978 that there has been no measurable warming for 33 years - but it wouldn’t have been proof that there was no warming trend. Short term variation can be very large.
So, my conclusion is that since basic atmospheric physics says that all else being equal, adding more CO2 to the mix SHOULD cause warming, and that we can measure that CO2 increase and know it’s real, then man is contributing to warming. Of course, we won’t have certainty based on empirical data that this is the case until we collect a few more decades worth of data so we can get out of the short-term where other variance dominates, but it’s strong enough evidence that it deserves to be the null hypothesis.
Once we get past there and start talking about long-term climate responses over decades, uncertainty starts to creep in because there are many positive and negative feedbacks that we do not fully understand yet. When we start trying to predict how much CO2 we will emit 80 years from now or what form our society and technology will take by then and what the cost of the warming will be to that future society, it gets to be borderline magical thinking. I would be willing to lay odds that we can’t predict even a simple variable like global GDP that far into the future with an accuracy better than chance.
But the basic physics of climate change and the immediate response of the atmosphere to CO2 increases is in a different category and I think the science there is sound and nearly incontrovertible.
So you do not understand it, but you do something about it.
Well, that is ok, but what it is not ok is to act as if the main theories were not explained before and even you pointed at good explanations too.
As pointed before that the earth is worming and that we humans are mostly responsible for the current increase is based on lots of research from several fields. But there are theories that are applicable that are more important than others.
I must say, Sam, that was one of the worst misrepresentations of IPCC statements that I’ve yet seen from you. I’m disappointed. I’m not going to go through every single misrepresented item in that long diatribe but I’ll address the major ones.
For starters, you state that “the biggest ‘positive feedback’ posited for large values of climate sensitivity is water vapor. What’s the consensus on what has actually happened with water vapor?” and then you provide a quote from the IPCC about large uncertainties regarding stratospheric water vapor.
The overwhelming proportion of water vapor effect is in the troposphere, not the stratosphere. Here, the operative factor is basic physics – the Clausius Clapeyron relation – that says absolute water vapor will increase in direct proportion to temperature. This constitutes the most powerful single feedback in the climate system, and there is no uncertainty about it whatsoever. Yet for some reason you chose to provide a quote from the IPCC about water vapor in the stratosphere, which is an entirely different beast, and then go on a page-long rant about how we apparently don’t know anything about water vapor!
FYI, water vapor in the stratosphere is indeed uncertain but it’s very small potatoes compared to the huge impact in the troposphere. Roughly about half of it comes from CH4 oxidation, a special case of water vapor actually being a very small forcing rather than a feedback, as one can see here. The rest comes up from the troposphere in various tropical and extratropical transport mechanisms but doesn’t amount to more than 0.3 W/m**2. Since the amount being added through the CH4 mechanism and especially the various transports varies wildly with different circulation phenomena like El Nino, stratospheric water vapor is a real wildcard. But it has nothing to do with the big picture of tropospheric water vapor feedback. In fact in the emissions-oriented forcings in the AR5, stratospheric water vapor isn’t even mentioned.
You make several statements about uncertainties regarding cloud cover. Yes, but this is not – and has never been regarded as – a major influence in the climate change balance and there’s been no systematic trend; clouds have both positive and negative feedbacks depending on altitude, and on balance are expected to continue to be a relatively small (and probably consistent) negative feedback.
You claim the predictions of drought got it all backwards because California should be getting more rain, not less. Completely wrong. The IPCC statement is about central North America, not the west, and it’s not a prediction, it’s an observational statement about what has actually occurred since 1950.
You somehow see fit to characterize the summary statements on the urgency of climate change mitigation issued by the US National Academy of Sciences, the national science academies of the United Kingdom, Brazil, Canada, China, France, Germany, Italy, India, Japan, Mexico, Russia, and South Africa, along with the American Association for the Advancement of Science and virtually every major science body on the planet as being politically motivated. This is nothing short of the worst of the denialist conspiracy theories and I’m pretty sure you don’t really believe that, but if you do, our conversation here is done.
You seem to try to refute the greatly improving accuracy of global climate models by claiming “[the scenarios] aren’t science. The IPCC calls them ‘storylines’.” Like “storylines” was supposed to imply “fairy tale”, or something. The concept of RCPs is that one of the major uncertainties in climate change projection is what our future emissions will be. The science can only operate based on specific GHG levels. The RCPs are intended to offer a range of projections based on different mitigation scenarios which helps establish danger levels and mitigation targets. The “storylines” are a holistic view of the entire socioeconomic pictures in the different scenarios, and you’re right, that’s not hard science, and no one said it was. But the underlying models are.
You claim the IPCC AR4 predicted beneficial effects. Absolute garbage. What has been said on occasion is that warming itself, disregarding all the extreme weather and biosystem consequences, may temporarily increase some crop yields in some northern latitude regions, but that these isolated effects will not be sustainable before lack of adaptation to climatic and ecological effects reverses them. Most other areas, especially Africa and tropical regions notably the most vulnerable to the consequences of crop failures, will see only negative impacts.
The IPCC AR5 SPM on climate change impacts states “Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts (high confidence). The smaller number of studies showing positive impacts relate mainly to high-latitude regions, though it is not yet clear whether the balance of impacts has been negative or positive in these regions (high confidence). Climate change has negatively affected wheat and maize yields for many regions …”
My rebuttal to your “complex adaptive system” argument stands – your argument is irrelevant when there is a long-term consistent forcing that drives the system in a particular direction. In this case, the constantly increasing thermal energy being accumulated by the planet. You seem to find contradictions in the fact that specific regional changes and specific timings are hard to predict yet we have confidence about long-term global impacts. There is no contradiction – this is a lot like the weather vs. climate argument. As in that argument, a lot of the misunderstanding stems from the failure to recognize that, for instance, global climate models can make reliable global projections despite having relatively poor spatial granularity, or otherwise treating spatial and temporal details statistically.
But rather than continuing these generic arguments, if you honestly want to understand the balance between our state of knowledge and our exposure to risk then I suggest you read the IPCC WG2 report from the AR5, which is on Impacts, Adaptation, and Vulnerability.
If there was some specific point that you feel I didn’t address let me know. If you just want to rant and promote denialism then I’m not likely to participate. After the way you distorted the statements of the IPCC I honestly don’t know any more how interested you are in a factual debate.
OK, that’s a start. I withdraw my previous comment questioning whether you’re interested in a factual debate, but I will say again that, for whatever reason, your previous post was a really egregious misinterpretation of the various things you claimed the IPCC to be saying, as I hope I clearly pointed out.
True but misleading. There is first of all a difference between systematic feedbacks and random natural variability. The latter might include unpredictable circulation changes that increase or decrease ocean heat uptake or just simply move heat around to where it absorbs or radiates more effectively or less, or change polar albedo on multi-year timescales, or volcanoes that produce atmospheric aerosols. But I think the central point is that it’s become vanishingly improbable that any of these factors are anywhere even close to the magnitude of GHG forcing over decadal timescales. Searching for these mystery factors as significant long-term climate drivers has become a lot like the ancient alchemists’ futile search for the Philosopher’s Stone.
You’ve got things a little bit backwards. Arguing that there are wild uncertainties about what those emissions levels will be is rather disingenuous since the whole purpose of the modeling exercises is to establish what they should be – or more specifically, establishing danger levels that we must not exceed. We can do a good enough job right now of predicting what the cost of that warming will be at any given level of CO2 – good enough to justify mitigation. The fact that we have no idea to what extent nations will heed the warnings is rather immaterial to what the science is telling us is likely to happen at specific emissions scenarios.
There’s a lot of invective and misconception to battle, but I just want to ask about one point:
Can we have a cite for the clause I’ve underlined? No, silly, not a cite that tropical rain forests thrive on tropical temperatures and rain , but a cite that they are expected to increase in coming decades.
The Amazon basin, ideally situated for rainforest (lots of land in the tropics) is expected to get much less rain in coming decades. Is the claim that new rainforests will develop in Africa? How long does it take a rainforest to develop? How about if it would encroach on a large human population already using the land for something else?
Deforestation (and the associated reduction in rainfall) may be a bigger threat to rainforests than just climate change. Some think Africa is moving towards desertification, but even if rainforests there somehow expand, they will be deforested! The claim in the above quote really does need some evidence.
I realize the rainforest issue was only a tiny part of your … comment, but I am sincerely curious about it.
No, it is not. In fact, it’s the basic stuff that is causing all sorts of uncertainty. You can claim each basic thing is easy to understand, but the moment you combine even two of the basics, (coupled models) it becomes so complicated the supercomputers give wildly different responses, so much that the range of possible outcomes is greater than natural variability alone. This is true even for basic global warming theory, where coupled models show results that do not match the theory at all. The basic theory starts with the increased concentrations of greenhouse gases, like CO2, reducing the amount of outgoing longwave radiation (OLR) to space; thus, energy accumulates in the climate system, and the planet warms. That’s as basic as it gets. But climate models don’t show this happening. Warming is shown to be primarily caused by an increase in absorbed solar radiation (ASR). So right away it becomes complicated, and in fact what we observe doesn’t match the theoretical.
The above example was in fact a response to your claim “the science there is sound and nearly incontrovertible.”
That paper and the information in it, and especially the conclusion, is about the basic global warming theory, and why models don’t show global warming happening as the theory predicts. (this can and will of course, be argued about, because once again, it’s not actually simple at all)
Rather than jump to an argument about what is being reported, look at the words on the page.
“but they do change our fundamental understanding of how that warming comes about”
Considering the topic, and the long period of time global warmers have been telling everyone that CO2 will cause climate change, or rather global warming, by “trapping heat”, it’s understandable that the non-expert public will view this with some skepticism. Especially when they observe a cat fight between “experts” about whether it’s true or not.
Or a cat fight on a message board fighting ignorance.
:rolleyes:
, but a cite that they are expected to increase in coming decades.
