Arguments
2014 SkS Weekly News Roundup #7
Posted on 15 February 2014 by John Hartz
- Climate change is here now and it could lead to global conflict
- Climate change means we will have to get used to flooding
- Freezing out the bigger picture
- Greens call for clear-out of 'climate change deniers'
- Ice storm paradox: It's colder because the Earth is warmer
- Obama prepares plan for deeper greenhouse gas pollution cuts
- Scientists certain human activity causes climate change
- Study sounds ‘El Niño Alarm’ for late this year
- The 'pause' in global warming is not even a thing
- UK floods making climate sceptics hot under the collar
- What iIs climate geoengineering?
- Winter weirdness: Is Arctic warming to blame?
Climate change is here now and it could lead to global conflict
The record rainfall and storm surges that have brought flooding across the UK are a clear sign that we are already experiencing the impacts of climate change.
Many commentators have suggested that we are suffering from unprecedented extreme weather. There are powerful grounds for arguing that this is part of a trend.
Four of the five wettest years recorded in the UK have occurred from the year 2000 onwards. Over that same period, we have also had the seven warmest years.
That is not a coincidence. There is an increasing body of evidence that extreme daily rainfall rates are becoming more intense, in line with what is expected from fundamental physics, as the Met Office pointed out earlier this week.
Climate change is here now and it could lead to global conflict, Op-ed by Nicholas Stern, Comment is Free, The Guardian, Feb 13, 2014
Climate change means we will have to get used to flooding
The political blame-game is in full swing over who is at fault for the current flooding crisis. But ministers debating local dredging operations in Somerset is a sideshow.
It will be a miracle if the winter of 2013-14 does not go down as the wettest on record – and frankly, it is difficult to see what could have been done to prevent massive disruption given the rainfall. But why is this happening?
The immediate answer is that the UK is “stuck” in a weather pattern – a common feature of our climate. But what is uncommon is the exceptional intensity of the rain and waves.
Climate change means we will have to get used to flooding by Nigel Arnell The Independent, Feb 11, 2014
Freezing out the bigger picture
Scientists refer to global warming because it is about, well, the globe. It is also about the long run. It is really not about what happened yesterday in Poughkeepsie.
The entire United States, including Alaska, covers less than 2 percent of the surface of the earth. So if the whole country somehow froze solid one January, that would not move the needle on global temperatures much at all.
Freezing Out the Bigger Picture by Justin Gillis, By Degrees, New York Times, Feb 10, 2014
Greens call for clear-out of 'climate change deniers'
The Green Party of England and Wales has called for a purge of government advisers and ministers who do not share its views on climate change.
Any senior adviser refusing to accept "the scientific consensus on climate change" should be sacked, it said.
Party leader Natalie Bennett said the rule must apply to all senior advisers, including those with no responsibility for environmental issues.
Greens call for clear-out of 'climate change deniers' by Ross Hopkins, BBC News, Feb 14, 2014
Ice storm paradox: It's colder because the Earth is warmer
With the American South locked in a deep freeze, you can be sure that plenty of the folks suffering through the snow and ice storms are interpreting the big chill as more proof that global warming is a hoax. “Warming?” they scoff. “How can the planet be warming when it’s so darn cold?”
People in other parts of the world seem to have no great difficulty understanding the science but, in the good old USA where quite a few people consider science just another political opinion, it is going to take a lot longer to get most people to accept the cold facts about a warmer world.
Ice storm paradox: It's colder because the Earth is warmer by David Horsey, Los Angeles Times, Feb 13, 2014
Obama prepares plan for deeper greenhouse gas pollution cuts
The Obama administration is quietly working on new greenhouse gas emissions targets to deliver to the United Nations, even as it struggles to craft regulations that will enable the United States to meet its current carbon-cutting goals.
With Republicans striking out at President Obama's climate change agenda as part of an effort to unseat vulnerable Senate Democrats in November, the administration is hardly advertising its effort. But according to officials involved in the process, the treacherous political terrain has not stopped the administration from forging ahead with developing new emissions goals.
Obama Prepares Plan for Deeper Greenhouse Gas Pollution Cuts by By Lisa Friedman and ClimateWire, Scientific American, Feb 11, 2014
Scientists certain human activity causes climate change
The problem with the public conversation about climate change is that not everyone plays by the same rules.
The majority of scientists follow the scientific method — a systematic approach to building knowledge. Starting in the 1820s, scientists began accumulating evidence, through the slow process of hypothesis testing and data collection, that adding carbon dioxide and other heat-trapping greenhouse gases to the atmosphere would warm the planet.
Now, after almost two centuries of research, scientists are as certain that human activity causes climate change as doctors are that cigarette smoking causes cancer.
Scientists certain human activity causes climate change, Op-ed by Simon Donner, Vancouver Sun, Feb 11, 2014
Study sounds ‘El Niño Alarm’ for late this year
A new study shows that there is at least a 76 percent likelihood that an El Niño event will occur later this year, potentially reshaping global weather patterns for a year or more and raising the odds that 2015 will set a record for the warmest year since instrument records began in the late 19th century.
The study, published on Monday in the Proceedings of the National Academy of Sciences, builds on research put forward in 2013 that first proposed a new long-range El Niño prediction method.
Study Sounds ‘El Niño Alarm’ For Late This Year by Andrew Freedman, Climate Central, Feb 7, 2014
UK floods making climate sceptics hot under the collar
The UK floods are not just causing misery for thousands of people around the country whose lives and livelihoods have been disrupted. They are also making a few climate change sceptics hot beneath the collar.
No doubt they are finding it an uncomfortable experience to realise that their misleading attempts to inform the public into believing that climate change poses no threat to the UK are now being undermined by the irrefutable evidence provided by the record rainfall and storm surges.
UK floods making climate sceptics hot under the collar by Bob Ward, The Guardioan, Feb 14, 204
The 'pause' in global warming is not even a thing
The idea that global warming has "paused" or is currently chillaxing in a comfy chair with the words "hiatus" written on it has been getting a good run in the media of late.
Much of this is down to a new study analysing why one single measure of climate change – the temperatures on the surface averaged out across the entire globe – might not have been rising quite so quickly as some thought they might.
The 'pause' in global warming is not even a thing by Graham, Readfearn, Plaen tOz, The Guardian, Feb 11, 2014
What Is Climate Geoengineering?
Climate geoengineering advocates have long argued over how to actually define the term "geoengineering." The precise details of that definition are important for various reasons, not the least of which is that it will determine what likely is to be subjected to the scrutiny and potentially complex and difficult legal governance processes that such a global scale climate-tweak effort would necessarily involve.
What Is Climate Geoengineering? Word Games in the Ongoing Debates Over a Definition by Richard Smolker, Truthout, Feb 12, 2014
Winter weirdness: Is Arctic warming to blame?
For Alaskans who have basked in record warmth, Atlantans who abandoned cars during a January snowstorm, or Californians enduring drought, this winter's extremes have been nothing if not memorable.
Drought or unusual warmth is in sync with the effects that climate scientists expect from global warming. But what about wintertime invasions of Arctic air into the US Deep South or into China, where, a new study indicates, record cold events became more frequent over the past 10 to 20 years?
For some climate scientists, January's extremes and the atmospheric patterns that nurtured and sustained them are fresh bits of information to apply to these intriguing questions: Has global warming's effect on the Arctic set the stage for persistent weather patterns that lead to extremes? If so, is the decline in Arctic sea ice the stage manager for the wintry events?
Winter weirdness: Is Arctic warming to blame? by Pete Spotts, The Christian Science Monitor, Feb 9, 2014
"The record rainfall and storm surges that have brought flooding across the UK are a clear sign that we are already experiencing the impacts of climate change." - Nicholas Stern, The Guardian, Feb 14, 2014
"Scientists refer to global warming because it is about, well, the globe. It is also about the long run. It is really not about what happened yesterday in Poughkeepsie." Justin Gillis, By Degrees, New York Times, Feb 10, 2014
Maybe Nick and Justin ought to get their argument straight. Is local weather evidence of global warming, or is it not? (No need to debate the answer here... That's not the issue I'm raising.)
The issue is this, you can't use an argument (i.e that specific weather is clear evidence of climate change) when it suits your cause (as with heat in Australia) and then turn around and argue the opposite when it doesn't suit you (as is being done with the cold in the US). Wet weather (in the UK) is evidence of climate change, yet dry weather (in California) is also evidence of climate change.
I'll leave the following question for the good folks here: Science is all about making hypotheses, testing those hypotheses with experiment or observation, and rejecting those hypotheses that are falsified by results. To be scientific, a hypothesis must be falsifiable. What exactly would constitute evidence against climate change? Or is climate change an unfalsifiable hypothesis?
Wow, that was a mess of blah blah blah and only one slight reference to the title.
"The shift to such a world could cause mass migrations of hundreds of millions of people away from the worst-affected areas. That would lead to conflict and war, not peace and prosperity."
Speculative pronouncements ("could cause") that fail to explain the cause and effect nexus or use specifics to illustrate why a mass migration would necessarily lead to war ("that would lead to conflict and war") is really just the editor trying to sell a few papers using an inflammatory headline.
Maybe there is a point to the authors position but it requires a little more explanation and details beyond just a catchy title, otherwise it becomes fodder for the “Catastrophic” AGW deskepticons who always look for the outlier of embellishment that they can anchor to while ignoring the underlying truth.
Russ R: 'The issue is this, you can't use an argument (i.e that specific weather is clear evidence of climate change) when it suits your cause (as with heat in Australia) and then turn around and argue the opposite when it doesn't suit you (as is being done with the cold in the US). Wet weather (in the UK) is evidence of climate change, yet dry weather (in California) is also evidence of climate change."
Who is "you"? It's not an SkS general position. Technically, all weather events as they have occurred are the products of climate change. You know that. Any change in global energy storage affects all parts of the system.
You're asking the wrong questions. What you should be asking is "How has global warming contributed to weather event X?" You can harp on SkS all you want, but the main posters here recognize the inextricable relationship between increasing energy storage and changes to global weather. TV newsfolk and politicians do not. The general public does not. When those entities talk about global warming, they say things like, "Scientists say this might have been caused by global warming." It's dumb, but then mainstream news and politicians dumb down things so their audiences don't go away.
In answer to your question: CO2 would have to stop absorbing/emitting thermal infrared. And "climate change" is not an hypothesis. It is a complex set of hypotheses that form a general theory.
DSL,
Sorry, I meant "you" in the general sense. Perhaps I should have written "one can't use an argument when it suits one's cause and then turn around and argue the opposite when it doesn't suit one." Is that better?
But when, in a single blog post, one presents excerpts from two articles (Nicholas Stern, in the Guardian, and Justin Gillis in the NYT) that take exactly opposite sides of the argument that a particular local weather event is evidence for/against climate change, one would think that one ought to notice the logical contradiction.
With all due respect, you're completely missing the point of my question, so I'll rephrase it.
What observable evidence would cause you to reject your belief that global warming is a serious problem that requires urgent policy action? (Feel free to replace the bit I've underlined with whatever statement aligns most closely with what you personally believe).
[JH] If you read the Stern op-ed and the Gillis article, you will find that the two authors are in agreement. The excerpts are the lead paragpraphs of each and do not contradict each other.
Russ, you perceive, or choose to perceive, a double-standard here. That is understandable, if you approach the whole discussion with a particular cognitive bias in which you start out believing warmists are inconsistent muddle-headed alarmists, and then merely seek confirmation of that in everything you read. The apparent double-standard disappears entirely if you accept, as plausible, that experts on a subject know more about this than the average blogger and drive-by commenter.
There are at least two reasons that your perceived double-standard is illusory.
One is that there is a big difference between a phenomenon being a sign of X and being proof of X. Thus, the spectacular heat wave in Australia over 2012/2013 is obviously a sign of anthropogenic global warming - subtract out the estimated contribution from AGW and the heat wave ceases to be all that spectacular. But it is not proof of global warming.That proof comes from a vast web of interlocking evidence that does not rely on any single element - and certainly not a single heat wave.
(In the same way, coughing up blood is a classic sign of lung cancer, but hardly constitutes proof of lung cancer. In someone who has not been investigated, it would be foolish to conclude from a bit of coughed-up blood that the correct diagnosis was lung cancer. In someone in whom the diagnosis is already established by other means, however, each new episode of coughing up blood is another reminder of the situation.)
A second reason that the double standard is illusory is that there is a genuine asymmetry in the current burden of proof that denialists and warmists face. A cold-snap cannot provide proof that AGW is wrong, and it cannot even be an indirect sign of the wrongness of AGW, because extraordinary claims require extraordinary evidence - and it would be truly extraordinary if the interlocking web of evidence for AGW all turned out to be wrong. A cold-snap simply does not have the evidentiary weight to challenge AGW. A single heat-wave cannot be proof of AGW, either, but it sure can be a sign of AGW, because the evidence for AGW is already so vast.
Instead of reading everything written on AGW from your particular cognitive stance, try looking for genuine understanding for a while.
"What observable evidence would cause you to reject your belief that global warming is a serious problem that requires urgent policy action?"
That carbon dioxide and other greenhouse gas levels are not increasing or even decreasing.
Russ, this strikes me as a cheap rhetorical device rather than a genuine discussion point. The falsifiability of climate science resembles most other aspects of science for which there is overwhelming consensus. There is nothing intrisically unfalsifiable about the key propositions underlying AGW; there is just so much accumulated evidence that it is hard to imagine what combination of errors and conspiracies could account for the current consensus and the multiple independent lines of evidence backing it up. (It is also hard to account for the lameness of the denialist attacks on AGW. If good denialist arguments existed, we would have heard them by now; it was this more than the positive evidence that helped convince me.)
Perhaps you could establish that yours is a genuine question either by answering the following question, or showing how your question is different?
Russ, for crying out loud, don't complain about other people not being precise when you yourself are not being precise:
Russ 1: "What exactly would constitute evidence against climate change? Or is climate change an unfalsifiable hypothesis?"
Russ 2: "What observable evidence would cause you to reject your belief that global warming is a serious problem that requires urgent policy action?"
1 does not equal 2, not even within the broad context of your posts at SkS. To answer your second question:
It would take strong evidence for a much lower sensitivity, and strong evidence against the mainstream sensitivity. I'd need an ECS around 1.3 (i.e. near balanced feedbacks). An ECS of 1.3C per doubling can't explain the last 50 years (the transient response is closer to that). My best estimate ECS is 2.8C, following the array of evidence in AR5.
Given an ECS of 2.8C and the long residence time for CO2, it's fairly certain that we're locked into major ice loss from WAIS and Greenland. It's also fairly certain that the rest of the land ice will likely go away fairly soon. The jet stream will likely continue to weaken, and that will mean persistent change in weather patterns. What we're talking about here is a period of 400-500 years, minimum, of persistent climate change. It's not a step change. It's something different, all the time. The paleo record tells us that the biosphere doesn't like abrupt change, and with CO2 rising faster than at any time in the last 300 million years, I'd say this is pretty abrupt. At the same time, the decline of cheap energy will be occurring. We're also facing, a few centuries from now, the inevitable end of phosphate production. And then there are the usual disasters. There is no better time than now to prepare for these conditions. Tomorrow it will be more difficult. I also note that you ask the question about policy without stating what you mean by "urgent." Do you think urgent policy action is necessary to push us off fossil energy, pre-empting a market-driven scrabble for energy that will, as it always has, lead to death and misery?
Leto: "What observable evidence would cause you to reject your belief that smoking causes lung cancer?"
"Smoking doesn't cause lung cancer; it kills the cancer," said my father as I gave him a last sponge of morphine. The parallels are simply astounding.
DSL @ 9: my father too.
Russ R. - Note the operative term, climate change. While there are frequently media errors claiming that either a single weather event either proves or disproves AGW, the statistics of extremes in warming (and for example the recent eastern US cooling that appears to be tied to Arctic warming) are the result in shifts of average weather, of the climate.
As to your rhetorical question, I don't think it can be left unaddressed. "Is local weather evidence of global warming, or is it not?" - It's absolutely evidence of climate change if the longer term statistics, the averages of highs, lows, rain or drought, change from previous values.
As to what would provide evidence against climate change? Weather remaining consistent with historical values (not the case across the globe), or some alternate explanation for the observations (not to be found).
As to whether or not it will be a serious problem, I would need to see some evidence that 2-4C changes in temperature over the next century, shifts in Hadley cell circulation, growth zones, plant productivity, and sea level rise won't induce truly significant costs and dislocations - and that evidence is sadly lacking. As I see it, the "business as usual" path is the most economically expensive policy choice available.
@1:
If I had a die with an extra pip added to each side, rolling a single 2 isn't evidence against the hypothesis that the die is tampered with. Rolling a single 7 however, is pretty convincing evidence!
I find it useful to keep in mind the full strength, though nowadays I prefer greenhouse chaos, disruption, or weirding.
climate change due to global warming caused by the accumulation of heat-trapping greenhouse gases.
The idea that somehow these words, which have been assigned meanings for convenience, can be used to argue away the reality they represent, is misleading and at this point dangerous to our futures, as we all comfort ourselves that it will go away by itself. It won't.
Russ,
When you start your argument with a false premise and then say you do not want to discuss it it becomes easy to win any argument.
It is completely false to suggest that the current "cold" weather in the US East is unusual. All the reports say something like "coldest since 1996" or "coldest since 1985". Please provide evidence that the recent weather is unusual compared to the weather in 1930, or stop making this completely false argument. January 2014 was the 53rd coldest January in the USA (out of 119), hardly a record. The record cold January in the USA was in 1979 and was 4.6C colder. Even combining the December/Jan data only gives the 33rd coldest on record. 2012 was the hottest year ever in the USA and was 3.2 F above average and 1.0F above the second hottest year. You call the 33 coldest Dec/Jan comparable to the extreme hottest ever? That is not a reasonable argument, perhaps you forgot to look at the data. The 53rd coldest January cannot reasonably be compared to the floods in England you cited whice are the worst in a record over 200 years long. Extreme record temperatures like the record hottest Australia heat wave are significant. Please provide data to support your claim of "record cold" lasting a month anywhere in the world, anytime in the past 5 years, that compares to the record hot Australia or USA records (which were yearly records). If such data cannot be found that proves you are making an empty retorical argument and do not care about the data.
It is perfectly acceptable to cite an extreme record like the floods as evidence of a change in weather while a typical cold snap from 50 years ago is not significant of anything. In the last year there have been 187 yearly high temperatures recorded in the USA and 44 cold records data, and it was a cold year compared to the past decade. This statistical summary of data proves that AGW is here. The 500 year drought currently occuring in California is proof that the problem is dangerous, or do you feel that we do not need fruits and vegetables in the USA any more?
I will be convinced that AGW is not happening if you can prove that Arhennius was wrong in 1896 with his predictions. He predicted: days warming faster than nights, winter faster than summer, land faster than sea, Northern Hemisphere faster than Southern and the Arctic warming fastest. You cannot even provide evidence that science from the 1800's is incorrect, I do not need to cite recent, better supported evidence. What will proove to you that AGW is occuring and is dangerous? It appears you are the one who has an unprovable hypothesis, since the data is overwhelming that AGW is dangerous and you cling to you beliefs anyway.
Russ,
The National Academy of Sciences, the International Energy Agency, and the World Bank all accept that global warming/climate change is happening, it's caused by humans and we should have started doing far more yesterday to stop it.
You seem to think the world must cater to your specific requirements for proof. The proof is here on this site. I suggest you would study the material more thorougly.
The proof doesn't have to perfect to be perfectly persuasive.
I for one have written my last post responding to your comments. No reply is ever going to convince you.
Russ R, please tell me why we should bother answering your questions, when you blatantly evade those presented to you by trying to deflect the discussion onto what Obama tweeted?
The question about falsifiability of climate change is a canard that we have seen here many many times before. However, to show that SkS regulars don't need to stoop to evasion, I'll answer your question:
"What observable evidence would cause you to reject your belief that global warming is a serious problem that requires [urgent] [considered, evidence based] policy action?"
Well for me a period without statistically significant warming that was sufficiently long for the test to have statistical power of 0.95 or more, during which atmospheric CO2 concentrations increased at the current rate or higher, and in the absence of changes in external forcings (such as volcanic or solar forcing), or known sources of internal climate variability (such as ENSO) that could plausibly explain the lack of warming.
Dikran Marsupial,
I was ignoring your question because it had nothing to do with Cook et al. (2013) whereas Obama's tweet did. I also had a fair number of responses to attend to that were on topic. Please don't take it personally.
That is an excellent, very well presented answer. But I'd argue that it's only a start. Warming itself isn't the justification for action. The effects of warming and their impacts on the environment, economies and societies are the reason to consider taking action.
I'm in the process of composing my own answer to the question, which I will share here.
Russ... Note that there is far more to DM's answer on the falsifiability of man-made global warming.
Even if all that DM lays out were to happen (95% confidence range, no other external forcings, etc.) there would still be a clear problem with discarding the theory since the theory explains far more than just modern warming. CO2 and greenhouse gas theory explains a whole ton of other stuff including amplification of glacial-interglacial cycles, PETM, snowball earth and more.
So, not only would one be in a position of needing a new theory to explain modern warming, we'd also have to explain a long list of other things that currently fit neatly into CO2 theory.
The theory is quite clearly falsifiable. The issue is that a theory as solid as this is extremely unlikely to be falsified.
And yes, the question at hand is also is a matter of impacts that justify taking rapid action today to avert future disasters. Those are harder to pin down. But the long and short becomes, those are risk assessments that have to be made. Some that are currently predicted may never happen. There are other impacts that we may currently be blissfully unaware of. So, how much are we willing to risk?
What I continually find astounding with the entire climate issue is that there are so many folks out there who seem so much more terrified by the solutions than they are by potential impacts.
Russ R wrote: "I was ignoring your question because it had nothing to do with Cook et al. (2013) whereas Obama's tweet did. "
I'm sorry, but that is utterly disingenuous, you wrote:
"The "97% consensus" that's you're reporting has nothing to say regarding any of the following, each of which is an essential link in the chain of reasoning that corrective policy action must be taken."
followed by a list of twelve elements of that chain which you claimed to have doubts about. Thus asking you for the reasons for your doubt about one of those links is relevant to the discussion of the concensus, because you raised it as an agrument against the meaningfulness of the concensus.
Russ also wrote "That is an excellent, very well presented answer. But I'd argue that it's only a start. Warming itself isn't the justification for action. The effects of warming and their impacts on the environment, economies and societies are the reason to consider taking action."
So it would seem that Russ R was not actually interested in the answer to the question, as he has done nothing with it, just used it as a springboard to ask another (you asked "what observations...", so wandering off into effects and economics is just evasion).
I'm sorry, but evading questions and asking rhetorical questions and then not doing anything with the ansers is blatant trolling.
@18Rob Honeycutt
Rob, I was going to say something similar; I would be really worried if DM's scenario were to occur. The choice: Question a ton of physics, or start looking for a mysterious phenomenon sucking energy out of the system. (Interdimensional Klingons?)
But your last sentence is really salient for interactions with the Russ's of the world. I have yet to see any of them willing to engage in a concrete discussion about a specific mitigation policy. I like to use rooftop solar as a thought exercise, but pick anything, like a carbon tax, and you will simply follow the same old path of evasion, rhetorical fallacy, and finally appeal to ideology and emotion. (It's Socialism!) And this from the side of the political spectrum that claims knowledge of economics and markets...
President Obama and the Mayor of Los Angeles discuss the severe economic effects California is having to deal with today because of Climate Change newspaper report here. Obama discussed these yesterday in the Central Vally of California, the producer of 1/2 the fruit and vegetables in the USA, threatened by unprecedented drought. This will be a multi billion dollar disaster this year. How long will it last?
Russ:
You did not address my data showing that you were comparing a normal cold month in the USA to record setting heat in Australia, the USA and record floods in England. Do you really feel these events are comaprable? It is a waste of time to continue our discussion if you feel normal cold equals record setting heat and floods. What do you think about the multi-billion dollar drought in California, predicted in advance by scientists?
I get the impression that you feel that the propaganda they put on at WUWT equals the data discussed here at Skeptical Science. If you want to continue to post here you need to review the data better.
"Well for me a period without statistically significant warming that was sufficiently long for the test to have statistical power of 0.95 or more, during which atmospheric CO2 concentrations increased at the current rate or higher, and in the absence of changes in external forcings (such as volcanic or solar forcing), or known sources of internal climate variability (such as ENSO) that could plausibly explain the lack of warming."
This would be a sufficient condition for taking notice and wondering at the cause of the observed pause, but surely not a sufficient condition for overturning all the other evidence in favour of AGW. If, by 'statistically significant', you simply mean p<0.05, then this merely means that similar results would have had a <5% probability of occurring 'by chance' in some idealised (nonexistent) world where AGW was false and there was no underlying warming trend. Given the a priori evidence for AGW in the real world, the likelihood that the 'significant' pause had appeared by chance (or because of some unanticipated/unknown confounding factor) would be much higher than 5% (possibly closer to 99%). You certainly would not be 95% confident that AGW had been overturned.
Dikran, I know you know this, but others might not.
That aside, Russ is clearly playing rhetorical games. The vast web of evidence in favour of AGW would require a matching web of counter-evidence, plus some explanation of why all the evidence and theory to date had pointed the wrong way. Several basic tenants of physics would have to be revised, for a start.
This discussion of climate change would be better if it was not being distorted by the comment that humans have caused climate change. The reality is that the operations of technological systems have disrupted natural operations, including the climate and the ocean. Emphasising that reality would undermine the arguments of the climate change skeptics.
@23
Well who is responsible for the creation and use of these "technological systems" if not humans?
That is like blaming over population on abstracts such as sexual deisre and the biological imperative but not the humans who are actually making all those babies.
As I've written before... one at a time Ladies and Gentlemen.
I have a few things on my to-do list than prevent me from devoting all my time to this site. I'll do my best to get to each of you, but there's only one of me to go around.
Dikran Marsupial,
I'm sorry you feel that I'm not giving you adequate attention. I gave a list of 12 question that were specifically not covered in the "97% Consensus" from Cook et al. (2013), but were all part a critical chain of reasoning to argue for policy action. I wasn't making an argument for or against any of the 12 questions. My point, which I'll repeat again, is that any reasonable person who fully accepts the "97% Consensus" could still oppose policy action for at least a dozen other reasons. Opposing policy action does not make one a "denier" or part of the "3%" of dissenters. Your desire to debate each of the 12 questions was not germaine to the point I was making. Sorry.
Russ R @25, with respect, your question about falsification is not capable of being answered in a succinct form. That is because the hypothesis you are asking about is complex, and a large variety of circumstances would count as falsifying it. For any answer that can be expressed within the space of a comment, or even a single (or several) blog post, you will be able to point to multiple other circumstances that would falsify it. In short, compelling evidence that:
would falsify my "... belief that global warming is a serious problem that requires urgent policy action". However, that is not a sufficient listing because lower expected emissions with BAU along with lower climate sensitivity would also potentially falsify that belief, and so on for a great variety of combinations of factors.
In short, asking for a full listing of circumstances that would falsify so complex a belief is unreasonable - and smacks strongly of an attempt at a rhetorical "gotcha". That is particularly the case given that you did not merely rephrase your question between your post @1 and that @4; but completely changed the substance of the question. You further changed the substance of the question @17 by shifting it from indication of a criteria that would falsify the belief, to a requirement of exhaustive criteria that would falsify it. (On that point, any falsifiable element is sufficient to make a theory scientific by the naive falsificationist criteria to which you appeal in @1. Therefore Dikran Marsupial's response @16 was entirely adequate. In contrast, your response @17 shifts the goal posts by expecting not one falsifiable element, but an exhaustive listing of those elements.)
If you disagree with this assessment of the situation, please list your exhaustive criteria of all circumstances that would falsify your belief that global warming is not a problem requiring an urgent policy response. If you are unable to do so, or unwilling, we can reasonably conclude that you have knowingly set up an impossible bar for rhetorical purposes.
Leto,
Sorry for taking a while to respond.
I do see a double standard here, and I also see the mirror image from the other side. The contraditory arguments they typically present are as follows:
I'm sure you can see the obvious logical contradiction and double standard there. Why is it not a double standard when your side does it?
Is there any weather event that could possibly be inconsistent with global warming? If not, isn't "consistent with global warming" a meaningless statement?
[JH] Manmade climate change creates a new normal. Weather events occur in the new normal, not the old normal.
Russ, elsewhere you write:
"The "97% consensus" that's you're reporting has nothing to say regarding any of the following, each of which is an essential link in the chain of reasoning that corrective policy action must be taken.
How much will GHG emissions rise in a "business as usual" scenario?
How much will atmospheric concentrations rise for that level of emissions?
How sensitive is the climate to increased GHG concentrations?
How long will it take for changes to manifest?
How will those changes impact ecosystems, economies, societies and individuals (considering both positive and negative impacts)?
What is the net cost / benefit of the expected changes (allowing for the possiblity and costs of adaptation)?
What policy actions are politically feasible and economically viable?
At best, how much can those actions actually reduce emissions below "business as usual"?
With what probability of success?
Over what time frame?
At what cost, and with what unintended side-effects?
And ultimately... will the probability-adjusted future benefits of policy action (discounted to present value), exceed the real direct and indirect costs of taking action, and will those costs and benefits be distributed equitably?"
(My emphasis)
The feature of "a chain of reasoning", like any chain, is that if one link fails, the entire chain fails. As such, your description of these twelve questions "essential links in the chain of reasoning" is a simply false description. I am inclined to say absurdly false.
It is false because these questions do not have yes/no answers. These are not logic gates. Rather the answers are in probabilities. So, it is perfectly reasonable to desire strenuous and urgent mitigation if you believe both that the mode (or median, or mean) of the Probability Density Function (PDF) of climate sensitivity is less than 2, and that the damage from moderate temperature increases are also low. All that is required for that to be rational is a belief in a long tail on the PDF for climate sensitivity, and a belief that expected costs rise exponentially with increasing GMST above 2 C. The result will be a very large expected cost from unmitigated emissions, even though combined with low "most likely" estimates of future temperature rises and costs.
Further, it is false because the questions are not independent. A person may believe in a low expected emissions with BAU because of an expected transition to low carbon energy sources in the near future due to rapid rises in the cost of fossil fuel energy due to easilly accessible and processed fossil fuel resources becoming exhausted, coupled with a rapid decrease in the cost of renewable energy. That same belief, however, will entail a belief that the cost of mitigation is very low, and possibly even negative (ie, it generates a positive benefit regardless any effects on GHG concentrations by smoothing the transition to renewables). Such a belief would (all else being equal) then place a high value on early mitigation based on a very low expected cost from mitigation coupled with being reational enough to entertain the belief that they may be wrong about future emissions pathways.
Alternatively, a person may expect low emissions with BAU but accept a very high value for climate sensitivity and a high value for the expected costs of increases in GMST, and consequently still strongly favour urgent mitigation.
The best that can be said of you list of questions is that they are all relevant. However, accepting low end probabilities on any of the questions does not compell rejection of the need for corrective policy without regard to other estimates.
Russ @27,
You would have a very good point if the a priori evidence for global warming versus global cooling were balanced. As it stands, though, you give every appearance of being a disingenuous troll, who made no attempt to understand the asymmetrical burden of proof I pointed out. I suggest you read up on Bayesian probability.
Try this: a hot spell is a reminder of where we are going; a cold spell is a reminder of what we will see less of; neither by itself is proof of anything.
I find it amusing that the very same people who declare climate to be a chaotic multidimensional morass, an epistemological swamp in which nothing can be known until everything is known, are just as happy to reduce discussions to a hot-vs-cold one-dimensional kiddy problem when it suits them - as you do when you talk of mirror images. There's your double standard.
I for one won't respond to you again unless you show some willingness to engage in true dialogue. And I say that despite the fact it is clearly a common troll tactic to project reasonableness, absorb nothing, and then sigh when the other side gives up.
If any lurking true skeptics are genuinely interested in the point Russ raises, pipe up and we can discuss it sensibily. Otherwise, I will stick with the policy of DNFTT.
Russ R makes a critical point. I would phrase it differently. If you have a theory that is not falsifiable, you only have a belief. If everything that can happen - good/bad, up/down, wet/dry, hot/cold etc., proves your point, then you have a religious belief. Unfortunately, both sides of this argument have become both political and religious beliefs.
Yes the talking heads on conservative news shows and people who discuss daily weather affects as proof of any climate effect should be ignored because they are not very knowledgeable. However, professional scientists that propose alternatives and who show data that don't match your theory cannot be discarded. Disprove them if you can, but you cannot scientifically ignore them.
No one who understands science will disagree that adding CO2, to a point, will increase heat buildup on the earth, but I think everyone agrees that the direct effect is small. Some even believe that once appropriate frequency ranges have absorbed all they can, that more CO2 will not cause additional warming.
The real issue is that the models that predict positive feedback result in catastrophic warming.
The problem with using models to predict anything, is that when the model is not accurate, all you need to do is add another parameter and you are all good for the next few years until the data deviates again and your model needs further tweaking. the model is always described as "better now, than before".
This kind do "science" is not much better than that from the talking heads of FOX News.
e cytochrome P-450 3A4 e
[JH] If an alternative to manamde climate change is disproved, it can be ignored by scientists as they proceed forward. It does not have to be disproved ad naseum.
Russ R wrote: "I'm sorry you feel that I'm not giving you adequate attention."
Again, this is disingenuous,I did not say that Russ didn't respond to my question, I pointed out that he responded evasively, making no attempt to answer it (by making a counter-attack that Cook et al. didn't address his list of 12 point - straight out of "rhetoric for beginners").
"I gave a list of 12 question that were specifically not covered in the "97% Consensus" from Cook et al. (2013), but were all part a critical chain of reasoning to argue for policy action. I wasn't making an argument for or against any of the 12 questions."
Again, that is disingenuous as you wrote:
"According to your definitions, I'm part of the "97% Consensus", but I still do not support the vast majority of proposed "climate policies" because I have numerous doubts relating to the dozen issues I've listed above."
which shows very clearly that you were making an argument about these 12 points, namely that there were numerous doubts about all of them. The fact that you didn't answer the question, but engaged in evasion instead shows that this was actually mere rhetoric and had no evidential basis
"Your desire to debate each of the 12 questions was not germaine to the point I was making. Sorry."
I didn't express any desire to debate each of the 12 questions, just the first one, to see whether your list of points actually had some evidential basis, or whether it was just a gish gallop designed to allow you to invoke the uncertainty monster to argue against any action on climate change. I guess that question has been answered now - it was just a gish gallop.
I suggest you read this article by Sir Paul Nurse, which explains why the sort of rhetorical arguments used in the polictical debate are an extremely poor approach to discussing science (as you have demonstrated here by frittering away your credibility by evasive rhetoric).
If the politico-economic arguments against action on climate change are so strong, it is hard to understand why those who hold that position seem so keen to substitute bogus scientific arguments in their place (e.g. the list of 12 issues, many of which have no substantial scientific doubt associated with them, e.g. item 2).
DNFTT, sorry Russ, it was your choice to behave that way.
Matzdj wrote: "Russ R makes a critical point. I would phrase it differently. If you have a theory that is not falsifiable, you only have a belief."
I explained how it is falsifiable here, please lets not have this degenerate into philosophy of science 101, this one is a real canard that has been discussed here many times before.
@Leto, that is pretty much why I included the part about the statistical power of the test - which is the frequentist answer to that issue (I prefer the Bayesian one myself).
Russ:
You continue to make the false claim that there was record cold recently. I provided data (NCDC website here) showing that your original claim of record cold in the USA was, in fact, only a normal cold front from 50 years ago. Deniers think it is cold since they do not look at the data. You have not provided data to support your claim. Your false equivalence where your say both sides refer to weather has been shown to be a rhetorical device. It is record hot, it is not record cold. Provide data showing a month of cold in the last five years anywhere in the world that was 1F colder than the previous record for that area. I provided data showing the USA in 2012 was 1F hotter than any previous record for the entire year.
When scientists say it is record hot it is record hot. When deniers say it is record cold, it is normal for 50 years ago. That is not an equivalent argument.
It is sloganeering to continue to post claims that have been shown to be false. Everyone else reading your posts sees that you continue to post claims you have not supported.
[JH] As you correctly point out, Russ R is now skating on the thin ice of sloganeering and excessive repitition - both of which are prohibited by the SkS Comments Policy. Future posts by Russ R that violate either of these prohibitions will be summarily deleted.
This comic perfectly illustrates skeptics claims about recent "record" cold. Perhaps Russ should look up recent temperatures in Atlanta and check if they were unusual from 1900-1950. It is likely that the climate has changed and skeptics only remember the past 10-20 years when it has been much hotter from AGW. The recent "record cold" is only record compared to the heat from AGW. Scientists look at the entire record.
michael sweet,
Here's NOAA's data on record setting weather, both hot and cold: http://www.ncdc.noaa.gov/cdo-web/datatools/records
YTD in the USA, approximatly 2.8x as many record low temperatures as record high temperatures (as I write this: 4790 low max and 3569 low min records vs. 1607 high max and 1349 high min records).
Is that sufficient data for you?
[JH] Lose the snark!
Russ R @36, why are you cherry picking just a single nation, over a period thought to be cold without comparing it to equivalent recent warm periods?
Indeed, why are you ignoring the all time records list from the page you link to:
Last 365 days: 187 warm records, 44 cold records.
And that on a purportedly cool year.
I should probably also have noted the monthly records:
Year to date: 137 warm records, 133 cool records.
And that purportedly in a very cold winter for the US.
Russ,
Tom is on target again. The daily records are often for shorter length records. The all time records are the real hard ones and, as Tom pointed out, there are 4.5 times as many hot all time records during your "record cold" period than cold records. Ditto the monthly records.
I notice that you have not even attempted to match the 2012 CONUS all time record high temperatures. During that year there were thousands more hot daily records than cold records.
So you match my Royal Flush with a pair of tens. Big deal!!! Find some data that compares to the all time hot US record, the all time hot Australian record or the all time record floods that you first mentioned.
I could name a half dozen additional comparable hot records off the top of my head. You cannot find a single month, anywhere in the globe that is comparable. "Cold records" give me a break!!
Russ,
Perhaps you have never looked at the 2012 data, you appear to have mostly read skeptic blogs. This March 2012 report documents 15,272 warm records broken (in March alone), three times as many records as you cite for 6 weeks. There were 21 instances where the low temperature was warmer than the previous highest temperature ever measured!!! Imagine such extreme heat that the low temperature was hotter than the previous highest high!! 25 states had their all time hottest March ever recorded. Every state in the nation recorded a warm daily record. No states had an all time record cold month in the recent "record cold", there was one state that was 4th coldest. In the recent "record cold" California recorded its third warmest January ever. 25 states had their warmest Jan-Mar on record in 2012 as compared to one state that was fifth coldest in the recent "record cold".
When I talk about record heat I mean record heat!! You must withdraw your comments suggesting that denier claims about "record cold" equal scientists claims about record heat. There has not been a comparable cold event anywhere on the globe for at least decades. I can name a half dozen comparable hot episodes.
Tom Curtis,
You make two very good comments @26 & @28. I once again must commend your analysis. I'll take them one at a time.
First, on the subject of "what would falsify your beliefs", you write:
I agree with you. The complexity makes it difficult to compile a list that is simultaneously concise and comprehensive, but you've done a nice job of sythesizing a number of critical factors. I'm glad to see that you've acknowledged these are "or" conditions, as well as recognizing that lower than expected risks across multiple factors in combination could result in no cause for alarm.
My list a bit different from yours, mostly because it starts from a different default belief. You'll note it's similar to the 12 questions I posted previously, which you mentioned @28. I agree with your assessment that the criteria are not independent logic gates, rather they're a series of probabilty functions that must be assessed in combination. You've expressed this concept very well.
I've collapsed the original 12 questions into a slightly shorter list of 9 criteria. Of note is the "and" between each one. (However, #9 is more "desirable" than "critical".)
For the record, I would believe that global warming is a problem requiring an urgent policy reponse if presented with compelling evidence that:
To hopefully avoid unnecessary arguments (as I should have done previously) let me spell out my own positions on each one.
Only the first five criteria are scientific... the remainder are political and economic questions. So, of the five scientific criteria, I find compelling evidence for three, and mixed or conditional evidence for two (climate sensitivity and net cost/benefit of warming.)
Of the four political and economic questions (which I acknowledge, are not the focus of this site), I find very little compelling evidence, and accordingly, am only supportive of a small number of climate policies where the benefits would so overwhelmingly outweigh the costs, even if the scientific evidence were less compelling (e.g. ending subsidies for energy, taxing carbon in lieu of income).
michael sweet,
This is getting a bit ridiculous. You accused me of starting an argument with a false premise:
I gave you a link to NOAA (http://www.ncdc.noaa.gov/cdo-web/datatools/records) showing that there were thousands of daily cold records , and 30 all-time cold records set in the USA so far this year.
But now you want to argue something different:
That wasn't the premise of my argument. I fully agree that there have been more warm records than cold records set all over the map in recent years. No argument here. Continuing to argue this line is a waste of your time and effort.
You complained that my mere mention of cold records (not their relative number but their very existence) was a "comletely false argument" and "sloganeering". I think the data show otherwise.
[DB] You continue to prosecute a specious point. Michael has provided the stronger case. As you still do not concede the point, it is time to let it go.
All: It appears that this discussion will continue. Please keep it civil.
Dikran Marsupial,
My apologies, I interpreted your initial question as a prelude to a point-by-point debate over each of the 12 questions... something that would take much more time than I could hope to have. Hence my desire to stay focused on the Cook et al paper.
Going back to your question from the other thread (I'm not sure if it's poor etiquette to cross threads like this, but if it is, I'll blame you for doing it first).
If there were no uncertainty, only one scenario would necessary. Personally, I believe that the RCP6.0 scenario is far more plausible than RCP8.5 for two reasons: the relationship between population growth vs. economic growth, and the relative cost of fossil fuels vs. alternatives.
1. As nations industrialize, their fertility rates plummet. (See every developed country on the planet.) I don't think it's likely we'll see a scenario where economies continue to grow rapidly and populations continue to grow rapidly at the same time.
2. 10 years ago oil cost $30/bbl and a solar panel or geothermal system cost a fortune. Two things have happened in the past decade... technologies have advanced bringing down the cost of renewable, carbon-neutral energy, while non-renewable resources have become more scarce, driving up the market price of of fossil fuels. (I'm in the process of converting my own home heating from electric to biomass, simply beause it costs less.) I don't expect either trend to reverse.
That said, I believe that even RCP6.0 could be sufficient for a "serious problem" depending on other factors.
Russ,
I am amazed that you want to continue. Did you read my post at 40? As Tom pointed out there were many more hot all time records during the time you are claiming it was cold. The winter is almost over so few additional all time records will be set, the summer has not started yet.
You said:
"Global warming? Are you serious? It's below freezing in Atlanta".
"So what if it's hot in Australia. That's only a local weather event. Weather is not climate."
I am using the 2012 US weather instead of Australia, the Australia data are comparable to the US weather. In 2014, Georgia had it's 4th coldest January. It was the coldest state in the USA. This is not exceptional at all in a 120 year record. In March, 2012, 25 states had their all time heat records. There were 21 instances where the cold temperature at night was hotter than the previous high temperature ever recorded during the day. In a movie you would not believe it.
Do you really want to argue that a single state fourth coldest is equivalent to 25 all time record hot events? That is just the start. Here is the 2012 annual report.
In 2012 19 states recorded their all time record hot year, most were extreme hot, much hotter than previous years. 25 additional states had a top 10 year for a total of 45 out of 48 states. The remaining three were 11, 12 and 30th hot. The temperature was 1.0F hotter than the previous hot record from 1998, an unbelievable amount higher, these records are usually broken by hundredths of a degree. Billions of dollars of damage was recorded. Your pitiful daily records cannot be compared to this record breaking heat. It is expected that with thousands of locations that some records will be broken every year. It is becoming tedious to transfer these sad records from the NCDC archve, read the rest yourself.
Your assertion that your cold records are comparable to the heat records I have cited is absurd. I could match these records easily with the heat records from Australia. Your assertion that there is an equivalence between your "cold in Atlanta" and the scorching heat suffered across the country in 2012 is astonishing. I am stunned that anyone could write that with a straight face.
If you consider that one state fourth coldest for a month is equivalent to 25 hottest ever years shattering all previous records that we will have to end our discussion.
You are undoubtedly also ignorant about the economic effects of these heat waves. I will not waste my time documenting them for you since you have already made up your mind and are not open to reviewing the actual data. Read the comic I linked in 35.
God save us from this deliberate ignorance.
John Hartz: thanks for the ice water.
[DB] You have made your point. That Russ refuses to concede does not overturn the fact that you have provided the strongest case. It is time to move on.
Russ @41, breaking the list down with description and your position grouped we have, to start:
(1) "In a BAU scenario GHG emissions will continue at a rate faster than can be absorbed by the biosphere, resulting in significantly and unsustainably rising concentrations"
Agreed.
(2) "The expected increase in atmospheric GHGs will result in a significant amount of warming"
The evidence is mixed. Just addressing the evidence before the IPCC, we have OAGCCM models with equilibrium climate sensitivities ranging from 2 to 4.6 C/x2CO2 (IPCC AR5 WG1, Chapter 9, see figure 9.42). Empirically, from the instrumental record, we have values from 0.8 (Lindzen and Choi) to 5 C/x2CO2, with 8 out of 20 being below 2 C/x2CO2, and 5 being 3 C/x2CO2 or above. Empirically, from climatological constraints we have three results, all lying between 3 and 4 C/x2CO2. Also empirically, from paleoclimate, we have just one from eleven results lying below 2 C/x2CO2, and one lying above 4 C/x2CO2, with the remainder lying between 2 and 3.5 C/x2CO2. There are also six results from attempted combined assessments, of which just one gives a result below 2 C/x2CO2, with the others all lying around 2.8 to 3 C/x2CO2. Of course, these are just modal (or mean or median in some cases) values, and the confidence intervals extend widely from the quoted values. In some instances as high as 9 C/x2CO2, but in no case below 0.5 C/x2CO2. (Data from IPCC AR5 WG1 Chapter 12, Box 12.2 Fig 1)
The mixed results in this case mean we have significant error margins in estimates. It does not mean there is a contrast between the range of values from empirical estimates and model estimates as you have suggested. That is a cannard formulated by focussing on just two or three studies that have conveniently low values, and not considering the full range of available evidence.
Given this, whether guided by empirical studies or the models, it is difficult to arrive at an estimate ECS range much different from the IPCC estimate that "...ECS is likely in the range 1.5°C to 4.5°C with high confidence, extremely unlikely less than 1°C (high confidence) and very unlikely greater than 6°C (medium confidence)."
I look forward to your ingenious argument that policy makers should ignore the assessment of experts on the topic, looking at the full range of evidence in favour of the opinion of non-experts looking at two or three cherry picked studies. Alternatively, I will be pleased to hear that you accept the IPCC assessment of climate sensitivity, and with it the likely temperature consequences for BAU.
(3) "The warming and related changes (sea level rise, etc.) will occur over time periods that are meaningful relative to human lifespans"
Agreed.
(4) "The changes will meaningfully impact ecosystems, economies, societies and individuals (considering both positive and negative impacts)"
Agreed.
(5) "The net cost / benefit of the expected changes will be negative"
Actually, the evidence is more equivocal than conditional. From the article we link to we find this graph, showing the cost estimates for the three major economic models for the costs of climate change:
As you can see, just one of three models shows benefits for small amounts of global warming, with the other two showing costs at all levels of warming. Claiming the "evidence is conditional" implicitly assumes that model is correct, in contrast to the other two. I do not see how that can be justified. As with the empirical climate sensitivity results, it looks a lot like choosing to pay attention only to those studies which give you the result you like.
Of course, I am inclined to give little weight to all three. That is because:
a) The models are not able to include a number of known and significant costs due to lack of data;
b) The models assume a prescribed economic growth, and therefore cannot include the costs of any reduced economic growth either due to global warming, or due to mitigation measures. As alterations in the rate of economic growth are likely to have far more effect on total costs and benefits than factors covered in the models, that renders them of dubious value. I should note that several global warming related weather disasters have already significantly impacted economic growth.
c) The models are unable to realistically cost the effects of loss of major eco systems, such as the Arctic, the Great Barrier Reef (both near certainties) and potentially the Amazon Rainforest. That means the costs they show are, in effect, best case scenarios rather than realistic estimates of the actual costs of global warming.
It seems a general feature of these economic models that they show little bearing to the kinds of impacts scientists tell us certain temperatures will have. It is telling that the FUND model, for example, shows only a loss of 7.5% of GDP at temperatures which scientists tell us will make the tropics seasonally uninhabitable for part of the year. The situation appears to be that the scientists cannot tell us the likely economic cost of global warming because they do not have the economic training necessary; but the economists cannot tell us either because global warming will likely take us to conditions so far outside normal conditions that the economists do not in fact have tools to deal with it. The general effect is that the uncertainty is much larger than indicated by the economic models, and while this allows the possibility of overall economic benefits to relatively high temperature increase (3 C), it also allows the possibility of catastrophic results at quite low levels of temperature increase (2, or even 1.5 C).
I will leave discussion of the policy issues until you have had a chance to respond on the science (and economics) issues.
Tom Curtis,
Glad to see we agree on most of the issues. That leaves only two... climate sensitivity and the magnitude (and sign) of expected net costs for given amounts of warming.
Each of these is a subject weighty enough to be it's own PhD thesis, so a blog post won't really do justice to either. Plus, I'm tight on time this morning, being at work, so this will have to be brief.
Let's start with climate sensitivity (we'll get to net cost/benefits later). I have two main issues that cause me to be skeptical of arguments for high sensitivity.
1. Fundamentally, climate sensitivity is a combination of forcing, feedbacks and thermal inertia. The forcing component of increased GHG concentrations is straightforward enough, the planet's thermal inertia is a bit less straighforward (since nobody seems to know exactly when all the supposed "warming in the pipeline" should appear), but the feedbacks are most assuredly not straightforward at all. There are countless feedback mechanisms in operation at any point, some positive and some negative. The magnitude of each will vary under different climactic conditions (e.g. ice albedo feedback can be a factor only at the margin of ice extent, which is of much greater magnitude when ice sheets extend down to 45N latitude instead of 70N). I wouldn't treat the sum total of all feedbacks as a linear multiplier and extrapolate it into the future. (Which is exactly what is being done when using ECS to forecast temperature changes.)
I would make a case that climate sensitivity was both higher and lower at different points in our planet's history, and will diminish if temperatures continue to rise. Were this not the case, the planet would have experienced runaway warming (or cooling) in the past when temperatures and CO2 levels were much higher (and lower) than they are today. Instead, geological evidence points to a planet see-sawing between two relatively stable equilibrium climate conditions, which suggests high sensitivity in the middle of the range, and low sensitivity at either end of the range. We can get into this in greater detail if you like.
2. Second, the model-derived estimates of sensitivity are a function of the assumptions relating to aerosol forcings, which vary significantly. Rather than retype the whole argument, I'll link to a post that summarizes it: http://www.coyoteblog.com/coyote_blog/tag/ecs. I agree with Meyer on this specific issue, with one exception... where he estimates ECS at 1.2C, I'd go with 2.0C based on Otto et al (2013).
Russ @41... You might actually take the time to read Otto 2013 before making such assertions as that they estimate CS at 2C. They state:
They very specifically argue that caution needs to be taken in doing exactly what you've done.
Otto et al are not making an argument against the current central estimates of 3C for ECS. In fact, they are saying quite clearly their estimates support those earlier figures.
Russ R wrote "Were this not the case, the planet would have experienced runaway warming (or cooling) in the past when temperatures and CO2 levels were much higher (and lower) than they are today."
Please take the time to see if your arguments have been discussed before on skeptical science. In the past, when CO2 levels were higher and lower, there was no runaway warming because the other forcings were different (principally solar brightening), runaway cooling actually did happen and runaway warming is pretty difficult to achieve as CO2 radiative forcing only increases logarithmically with concentration, but e.g. ocean degassing only rises linearly with temperature and the radiation of energy from the earth proportional to the fourth power of temperature (Stefan Boltzman law).
I suggest we DNFTT until Russ actually starts checking up on whether his arguments have any merit before he uses them.
Re:Climate sensitivity as a function of CO2
from
Climate Sensitivity, Sea Level, and Atmospheric CO2
James Hansen, Makiko Sato, Gary Russell and Pushker Kharecha
NASA Goddard Institute for Space Studies and Columbia University Earth Institute, New York
Fig 7b)