Tackling the Climate Attribution Puzzle
In Nature this week, Quirin Schiermeier has written the most lucid, evenhanded article I’ve read yet on the vexing issue of extreme weather/climate change attribution. He also reports on some notable developments. For example, Quirin writes that
in the past year, climate researchers in the United States and Britain have formed a loose coalition under the banner ‘ACE’ “” Attribution of Climate-related Events “” and have begun a series of coordinated studies designed to lay the foundations for a systematic weather-attribution programme. Ultimately, the group hopes to create an international system that could assess the changing climate’s influence on weather events almost as soon as they happen or even before they hit, with results being announced on the nightly weather reports.
There’s a related and (equally excellent) editorial in the same issue, which asserts that climate scientists
have an obligation to provide more coherent answers to queries (or doubts) as to how global warming influences our weather. An attribution system with ample resources, running in near real time, could prevent scientists’ answers to those questions seeming either too cautious or too alarmist and speculative. It could also prevent the public from getting the (false) impression that climate research is confined to the virtual world of climate models and has little to offer when it comes to current reality, or that climate science is a quasi-experimental field that yields scary but mostly unverifiable results.
In fields where logic is still attempted, this would be known as assuming the conclusion. Climate isn’t changing in any way that is unnatural. If it were, someone would have used science to prove it. That is, science, not an opinion poll of people who get paid to say it is changing. Since no such science exists, attribution of a particular weather event to a source which is merely an unproven theory fails simple logic.
But the main problem with such attribution is that it is always extremely uncertain. Judith Curry has a number of posts on this matter. So, methinks, no matter how many scientists are assembled in the avowedly loose ACE network, little more than speculation and very wide uncertainties could come out.
See Dr Curry’s take on this news at http://judithcurry.com/2011/09/08/extreme-measures/
“Scientifically unsound” is the assessment of Judith Curry, a climatologist at the Georgia Institute of Technology in Atlanta.
Mine is the same except I could use stronger language.
Curry’s position on attribution is indeed clear:
Since Hurricane Katrina, the issue of whether global warming is contributing to specific extreme events has been discussed in the media by scientists. Exactly what would someone do with the information (if they could assume it accurate) that 5% less rainfall would have fell [sic] in Pakistan without global warming (95% of the rain would still cause massive flooding)? Would this help people adapt better to extreme events (there is already a large adaptation deficit in most places)? Would it provide fodder for litigation or the “blame game” to motivate more international humanitarian assistance? Would it help build political will to support CO2 mitigation policies?
One would imagine a scientist would be in favor of a better understanding of a changing climate’s impact regardless of whether it bolstered her political preference or not.
Because more accurate attribution cuts both ways: as the Nature article correctly notes:
If the surge in frequency is a result only of natural cycles, it will probably subside someday soon.
So it’s not clear why Curry is opposed to even the attempt to address the question more rigorously: at worst it will fail, and at best it will provide evidence for the “lukewarmer” position, if it is correct.
@5 Indeed.
Even more amusing is that she turns around and says basically that there is already a group doing a good job of the very thing she just called “scientifically unsound”, so no need for ACE! It’s like she doesn’t even read her own writing.
PDA says “So it’s not clear why Curry is opposed to even the attempt to address the question more rigorously”
I do not think she “opposes” it. She simply says there is no way to achieve such attribution.
One should remember that climate is defined as the average weather conditions, and their average degree of variability, over a relatively long period. The standard period is 30 years, but many natural cycles are longer (multi-decadal and secular). IPCC projections are for the average of 2080-99, with some references to the trajectory between the base period (1970-99) and that target period.
Another caveat: even if there were a projection of a 5% decrease or increase in precipitation, it would refer to the average precipitation of a long period, not implying that every specific event (such as the 2010 monsoon rains in Pakistan) would be 5% less or 5% more than they actually were. All this without going in to the more serious matter of the validity of climate models to make projections into the future, which is a totally different story.
“Would it help build political will to support CO2 mitigation policies? ”
While mitigation policies would be more politically palatable if extremes were linked to AGW, really, the important step would be for immediate adaption policies that account for the projected increases in extreme events for the amount of heat/energy we’re already owed over the next 50 years. But…
It is amazing how Judith was treated when she went all heretic, but gets ignored when she makes extreme anti-mitigation missives like this one. According to her, scientists should not get at all involved in policy, just stick to the science. I would hope people realize that undermining efforts to study weather because she’s read other scientists’ minds and thinks a project will “build political will” to something she apparently doesn’t like — that’s a policy position. In fact, advocating for ‘no policy’ is a policy position. Of course, just having the knowledge that AGW = extreme weather doesn’t equal any particular policy. It could lead to several different options. I assume this means that any scientific exploration that starts with a hypothesis that, if true, would lead to policies she doesn’t like, should be tossed away also because, apparently, the scientific method can no longer be trusted. Those danged climate scientists will always figure out which science will get them the polices they desire.
Academic freedom be damned. The police are here.
They need a high-resolution version so that instead of blaming some bad weather on “cars” they can narrow it down to the location and owner of the car to blame.
Maybe Franny from 10:10 could help out ?
Ew geez…she doubles down in today’s ClimateEtc post.
http://judithcurry.com/2011/09/08/extreme-measures
“Never let a good disaster go to waste in terms of trying to play on people’s emotions to generate support for CO2 mitigation policies.
Fortunately, there seems to be little prospect for ACE in the short term”
I have added a clarification to my original post:
Clarification. People seem confused as to why I am praising the NOAA group, while I am not at all impressed by the proposed ACE effort. The NOAA group examines the historical data record, looks for past analogues, and interprets the extreme weather event in the context of the weather and climate dynamics. In the three examples of “Whats happening now”, they explained the Russian heatwave, the snowy winter, and the tornado outbreak in the context of natural weather and climate variability. By contrast, the ACE effort is focused on using climate models to assess the fraction of the event that might be attributed to global warming. It is the use of climate models for this exercise that I object to, which I explained in a previous post.
http://judithcurry.com/2011/01/15/attribution-of-extreme-events/
The whole idea is insane.
Are they really really really going to collate weather reports from round the world and in “near real time” decide what can be blamed on “evil car drivers/republicans/denialists/people staying warm in winter” ?
I do not think she “opposes” it. She simply says there is no way to achieve such attribution.
In the latest judithcurry.com post, she doesn’t say it’s a bad idea, just that it’s impossible… but in the earlier post, which I quoted @ 5, she did say that if it were possible, it would be a bad idea.
That pretty clearly adds up to opposition in my mind.
And as Grypo points out, the much more likely short-term policy consequence would be greater emphasis on adaptation, which is generally a touchstone of the lukewarmer position. Indeed, Curry herself noted that “there is already a large adaptation deficit in most places.”
So here we have climate scientists handing the lukewarmers what would either be the vindication of their position, or the means by which their preferred policy prorities are advanced… and Curry’s waving it off, saying “nah… it’ll never work.”
It’s the cli-sci equivalent of “you should pass this bill today.” They’ll harm their own interests rather than admit that the other side might have a halfway-decent idea.
PDA, you miss my point. The climate scientists seem to be arguing that this attribution exercise is important for decision makers. I am arguing that it is not. If anyone figures out how to do it in a credible way, it is perhaps of some scientific interest. Focusing dollars and scientific effort on something like this detracts from making progress in more scientifically fruitful and useful areas.
One further comment. As i wrote in my previous attribution post, I think the idea of this extreme event attribution is fundamentally flawed, given the chaotic nature of the atmosphere among other reasons.
Dr. Curry, rest assured that I agree that if anyone does not figure out how to do attribution in a credible way, it is of no scientific interest.
I doubt that any of the scientists involved in the ACE effort disagree.
One might ask them.
The flailing about here is a little hard to watch.
Going from declaring something a priori scientifically unsound (because it uses models (bad!) and not historical data (great!)?), to agreeing that it would be useful if done successfully is… quite an evolution.
@16 PDA:
Dr. Curry, rest assured that I agree that if anyone does not figure out how to do attribution in a credible way, it is of no scientific interest.
I doubt that any of the scientists involved in the ACE effort disagree.
Ouch.
Gee TB, you seem to be saying that it should be just as easy to spot trends on weather as in climate. If that is indeed what you are saying, I find it not only curious but a bit I’m conflict with the published literature.
The outcome of using already poor performing models to link extreme events is 100% predictable. The finding will be “more attribution than we thought”. A funding feeding frenzy will ensue where each study progressively finds more attribution than the last. All while extreme events remain steady or decrease. Another unfalsifiable ponzi research scheme.
Shorter version :”Many people wish to make attribution claims where there isn’t any evidence to support it. We will try our hardest to wring out anything that supports this position.”
This along with the IPCC’s stated aim to “assess scientific information relevant to human-induced climate change”, is what I believe is a fatal flaw of modern climatology. It’s the scientific equivalent of a push poll.
Here’s a what I think the IPCC’s stated aim should be: “to assess scientific information relevant to determining how the climate functions.”
@18 Tom Fuller:
Sorry, I honestly can’t understand what you’re saying. I think you may have had some autocorrect difficulties.
My, my. This is getting too funny, in a desperate sort of way. ACE. Another IPCC. Just what the world does not need.
The AGW gang has been unofficially attributing anything and everything to their gravy train cause, from alleged drowning polar bears to islands that are not sinking to icecaps that are not melting.
Wrapping this snake oil sales program in an official ‘coalition’ is absolutely meaningless, and more of the same.
I can’t belive you take this obvious political move seriously Keith… but then there’s not much else left to cling to I suppose.
A funding feeding frenzy will ensue where each study progressively finds more attribution than the last. All while extreme events remain steady or decrease. Another unfalsifiable ponzi research scheme.
Well said. And, after the 2012 elections, and the money spigot shuts, they will be an ace in the hole.
I don’t know what the duck he’s saying either, TB.
Look, this is no-lose for the lukewarmers. Either it won’t work (another FAIL to club the scientists with), or it works and it confirms that the climate is not changing (a strike against calls for expensive mitigation), or it works and confirms that the climate is becoming more dangerous (so we need adaptation now).
The only people whose oxen might get gored here are the climate scientists, and the rejectionists who say climate change isn’t happening at all.
And we know lukewarmers aren’t rejectionists.
Right?
#24,
You really think they’ll find that there’s no connection? They’ll analyze/manipulate/torture the data until they get the answer they want. And the answer they want is that we have to institute a policy to change the future climate.
That’s the problem. They’re not looking for whether the current weather patterns are attributable to climate change, they’ve assumed they are already and aren’t interested in saying otherwise.
#25,
That’s not an argument specifically against ACE. That’s an argument that cli-sci is irredeemably corrupt.
And that’s fine if that’s your argument, which I compress (inelegantly, perhaps) into the term “rejectionist.”
Is that what Curry is saying, though?
I think I understand what he (Tom) is saying. He’s asking whether TB thinks that picking up trends in weather is as easy as doing it in climate. TB hasn’t actually said this. But for all intents and purposes, that’s not what we are discussing. Here’s the divide — we all (TB and Tom included) know that finding these trends with our current data is impossible. Not matter how we slice it, the natural variation is such that we can’t know whether or not it is possible for several 100 year floods to happen within 10 years is outside of possibility of natural variation. Saying that it is significant would be unsound. But it would just as unsound to say that they are not significant, or that they can say conclusively that anthropogenic effects had nothing to do with it.
Fractional attribution modelling is used to see what percentage chance is there that the event would have had with and without man made factors. IOW, what is the fraction of risk attributable to man. I believe this is what Judith is calling “unsound science”. Unsound enough to not even try. I’ve read the threads and I haven’t seen the reason for this conclusion. All I see is that there is a fear that this type of modelling will undoubtedly lead to certain conclusion, and that it will lead to certain policies. i don’t see where the evidence for this conclusion is. I’d like to, or even see detailed conclusions about the unsound science behind fractional attribution modelling.
But this all gets back to the conclusion that the IPCC doesn’t look hard enough at “natural variation”. I find no evidence for this either. Quite the contrary.
@ grypo (27)
I’m afraid you don’t understand how the science works (or pretend to).
But it would just as unsound to say that they are not significant, or that they can say conclusively that anthropogenic effects had nothing to do with it.
Nobody outside the loony bin says (or needs to say) that they are insignificant. The burden of proof is on those who wants to prove significance.
… what is the fraction of risk attributable to man. I believe this is what Judith is calling “unsound science”. Unsound enough to not even try. I’ve read the threads and I haven’t seen the reason for this conclusion.
The simplest explanation is that there is no reason to think otherwise. It’s a default conclusion until the opposite is proven, This is how science operates. We know that weather is chaotic and unpredictable. We know that natural variability is large and the signal is small. We know how bad climate models are how even the short term weather forecast could be very unreliable. So, why would anyone believe that it’s possible to pull out such a fractional attribution out of the heap of computer simulations?
I’d like to see something like a proof before the money is spent and Joe Romm is launched to announce on TV that 40% of the next hurricane is due to AGW.
“The simplest explanation is that there is no reason to think otherwise.”
Upon what science do you apply this hypothesis? You are making a subjective evaluation here. The simplest explanation could just as easily be that that changing the atmosphere, changes the climate, which changes the weather. In fact, I don’t know any experts who would argue with that statement. The idea is to figure out how. That’s what fractional attribution is useful for.
“So, why would anyone believe that it’s possible to pull out such a fractional attribution out of the heap of computer simulations?”
Whether or not you believe it or not is not really a concern of mine.
I’d like to see something like a proof
A proof of what, exactly? You guys are always asking for “proof” without bestirring yourselves to define what “proof” would even mean in terms of science, what the criteria would be for judging such a proof valid or invalid, with +/- tolerances and requirements for evidence.
It seems obvious that if you continually demand an undefined something, you can always say “not good enough,” regardless of what you’rte presented with.
I’d like it if that was my job.
@ grypo
So you are not pretending, you really don’t understand.
It’s not a hypothesis. It’s a normal scientific skepticism that meets any new proposition. Every new thing in science needs to be proven. Otherwise it’s fairly assessed as scientifically unsound. When and if they explain why this is a sound approach the assessment will change. What you suggest as an “explanation” is better known as a hand-waving. What we need here is a quantification that is nowhere near. Whether you believe in the opposite makes no difference.
@ PDA
A proof that the models can be meaningfully used to quantify the fractional attribution. By “meaningfully” I mean the error bar associated with the fraction being a lot smaller than the fraction itself. Sue to the nature of the problem (see my previous comment) one expects the fractions to be small but errors large. This could be an incorrect view but it’s a normal null hypothesis. If this is not so it needs to be proven.
True that demanding undefined something and moving the target is a nice job to have. At the same time, cranking up gazillions of potentially meaningless computer simulations and announcing conclusions of monumental importance with huge policy implications is a great job to have.
Sashka,
Rest assured that I agree that an assessment like “10% +/- 20%” would be meaningless.
I doubt that any of the scientists involved in the ACE effort disagree.
One might ask them.
The way the funding process normally works, before the funds for research are allocated, the PIs need to put forward an explanation why the proposed approach is expected to work. This is typically done in the research proposal to a funding body like NSF and rests on the body of established peer-reviewed work. Nobody has to chase them with the obvious questions. If they have answers they should get them published.
“It’s not a hypothesis. It’s a normal scientific skepticism that meets any new proposition. Every new thing in science needs to be proven. ”
That’s a meaningless statement. What you are proposing is a hypothesis. One which competes with others. I don’t think you understand what is being tested. We are not testing whether weather is chaotic. We are testing what effect man has on extreme events given a priori facts about man’s contribution to changing the atmosphere. That’s what the attribution models are for. It comes down to the fact you don’t like them and don’t want to spend money on it — not what your “understanding” of constitutes a hypothesis or not.
This may be meaningless to you but only because you have no idea what you are talking about. Nor about how the science works as you have amply demonstrated already. Nor do you show basic reading comprehension. I never said or implied that we are testing whether weather is chaotic. I know what we are testing and I know what the models are for. The problem is (for the last time) that the models are not designed for the task nor shown to be up to the task.
It’s meaningless because you are having a conversation with an imaginary person about what may or may not be null hypotheses. That’s not what we are talking about. And no one is really talking how to frame the conversation about extreme events. We are talking about the fractional attribution of the models — to which your opinion is…
“The problem is (for the last time) that the models are not designed for the task nor shown to be up to the task.”
Please show us why. That would be the point of a thing like ACE. If you have hidden information as to why it’s impossible or not worth trying or a waste of money, back it up with convincing details. So far we have Judith’s extra-sensory perception about the intentions of the modelers and their policy wants. Still waiting on better information than that.
How would someone “prove” a hurricane was increased by 5% due to AGW?
How would someone “disprove” it?
How would computer simulations that have already been shown to not be able to unwind natural and human caused variations, now be used to do extreme event attribution studies with any useful accuracy?
Sure, they can run some simulations, and some numbers will come out, but there is no verification / validation to be performed.
Using unsound models will not result in sound attribution numbers.
It is unsound science until the models can show they are successfully unwinding natural and human caused variations.
Imaginary person? Would that be you?
The null hypothesis is not what you or I want it to be. It’s the same thing every time. Presumed wrong until proven correct.
Show you why – what? Why the models were not designed for that? Well, how does one generally show that A is not B? For example, how would you prove that you are not an alien? You’d probably say that there is no need to prove it because you’ll be by default presumed human until otherwise proven (and you would be right). Same thing here. I don’t need to show anything. They must. That’s how science work whether you like it or not.
#37
The assumption that hurricane are becoming more dangerous should be evaluatable, in that average hurricane strenght should be increasing. But we’re not seeing that. Instead, we’re seeing record low tropical cyclone strength/activity (according to Maue at FSU). And THAT’s the problem. The data doesn’t support the conclusion that hurricanes are becoming stronger. They’re not. So if a study comes out saying they are more dangerous, it’s not because of the hurricane…
As for droughts and thunderstorms and tornadoes, you should see a long term trend that shows this being the case. As far as I have heard, no such long term trend exists. That more damage is occuring is therefore not due to the weather but rather due to humans living where those weather patterns are more common.
Ace does raise some interesting questions:
If I make a tee time for saturday and it doesn’t rain, how much of not-rain is attributable to AGW.
If I’m a farmer and it rains enough to grow a good crop, but not too much to prevent harvest, how much of good-crop is attributable to AGW
If todays weather is within, say, 2-sigma of the average for that day, what percent of average weather is attributable to AGW.
Seriously, though, the whole premise is FUBAR because it relies on the assumption that AGW only causes bad weahter. Although, to be precise, the post says “changing climate”, which actually leaves the real attribution question open: how much of “changing climate” is anthropogenic.
Just another silly means to achieve certain political ends by scaring people.
Dean_1230,
Wind strength is not the only attribute of hurricanes that is important.
Hurricane Irene brought tremendous rainfall to the Northeast causing the worst flooding in Vermont since 1927. It is a reasonable question to ask whether the huge amount of rainfall was caused in part by global warming. The ocean temperatures which are responsible for the water content of hurricanes have been above normal.
If these types of storms are going to be more numerous, the location of roads and homes will need to be modified considerably. Attribution is an important question that needs to be resolved.
Tom Scharf
@37,
Computer simulations have been shown which unwind human caused and natural variations. Check out the graphs on this page.
http://www.skepticalscience.com/climate-models-intermediate.htm
“Same thing here. I don’t need to show anything. They must. That’s how science work whether you like it or not.”
You are stuck on this null hypothesis conversation but people are asking for reasons why ACE can’t test a hypothesis fairly. Do you see the logic misstep? “Why not ACE?” — “You need to proof” — “Why doesn’t ACE make a good tool for that?” — “You need to prove your case.” — “What do you know about ACE that makes you think it cannot deal with these questions?” — No answer… except… “cranking up gazillions of potentially meaningless computer simulations and announcing conclusions of monumental importance with huge policy implications is a great job to have.”
So your only answer is similar to Judith’s, afraid of what the models will tell you and other about possible policy. No discussion about how the models work or why they would always point to humans as a cause. And also you try to elevate yourself by commenting on other’s knowledge of “how science works”. So basically you don’t think the models are good, but don’t discuss why, and hilariously don’t think it is necessary to. Okay, so you don’t have a good answer. So what?
#41,
“If these types of storms are going to be more numerous, the location of roads and homes will need to be modified considerably. Attribution is an important question that needs to be resolved.”
If these storms are going to be more numerous, wouldn’t you expect to see that already in the number and/or strength of hurricanes? The temperature has risen a degree in the last century (independent of cause). If the theory held, then the number and/or strength should also have increased. And yet it hasn’t according to the experts.
Hurricane Agnes (1972) was a cat 1 storm and did incredible damage in PA due to flooding.
http://en.wikipedia.org/wiki/Hurricane_Agnes
Tropical Storm Allison (2001) dropped 40 inches on TX in 2001
http://en.wikipedia.org/wiki/Tropical_Storm_Allison
Please offer some evidence (other than the exact path it traveled)that anything that happened with Irene was unique.
Jeff Masters
One shouldn’t compare rainfall from a storm in Texas which is on the gulf coast, to New England which is much further North.
http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=1896
Irene’s impact on the mid-Atlantic and New England
“….However, this year sea surface temperatures 1 – 3°F warmer than average extend along the East Coast from North Carolina to New York. Waters of at least 26°C extend all the way to Southern New Jersey, which will make it easier for Irene to maintain its strength much farther to the north than a hurricane usually can. During the month of July, ocean temperature off the mid-Atlantic coast (35°N – 40°N, 75°W – 70°W) averaged 2.6°F (1.45°C) above average, the second highest July ocean temperatures since record keeping began over a century ago (the record was 3.8°F above average, set in 2010.) These warm ocean temperatures will also make Irene a much wetter hurricane than is typical, since much more water vapor can evaporate into the air from record-warm ocean surfaces. The latest precipitation forecast from NOAA’s Hydrological prediction center shows that Irene could dump over 8 inches of rain over coastal New England.”
There were actually 20 record rainfall events recorded in the Mid Atlantic States and the Northeast.
45 Eric,
So what?!
Ocean temps are flat for years. Hurricanes and tropical storms are down. Irene was a hurricane. It did what hurricanes can do. This is proof of what? How?
We can point to all kinds of places which had more extreme weather of one sort or another 20, 40, 50, 100 years ago. What does that say about climate during those periods? Nothing. But Irene in 2011 is special? Because you want so desperately for it to be special and meaningful?
Hope and change may be enough to win election, but it’s not science.
Stan,
Ocean temperatures are increasing. The last 2 years were the hottest ocean temperatures in a century. Higher ocean temperatures mean more heavy rainfall events for sure, even if the effects on wind strength in hurricanes is debatable.
Your are in denial.
47,
Hmmm. Roger Pielke, Sr. and a number of others seem to disagree with you. And they provide graphs which make it clear that there hasn’t been any warming since 2003. I guess you’ll have to put me down as unconvinced by your assertions re: warming oceans.
Of course, even if the ocean temps were warming, that wouldn’t prove your argument at all. You may see me as being in denial, but there can be absolutely no argument that your assertions fail the test of logic.
Your faith is admirable. I know ministers, priests, and rabbis who would be jealous.
@ grypo
people are asking for reasons why ACE can’t test a hypothesis fairly
Because they don’t have tools for that. The answer is indeed the same as Judith’s. The models cannot tell you anything about policy, not even in theory. At the very best they could do what ACE purports they can: compute fractional attribution and put an error bar on the number. The latter they don’t discuss, of course.
The reasons why models are highly unlikely to help with this project are outlined for example in 28. I’m sure Judith would provide more details for you if you would listen to a reason.
Stsn,
I should have paraphrased Masters more accurately. See my post @45 where Masters’ actuall quote appears. He is talking about the warmest ocean temperatures in the North Atlantic between North Carlina and New York. From this Masters correctly predicted Irene would be a wetter than typical hurricane in the Northeast.
Although you didn’t provide a link, I believe Pielke Sr is talking about global ocean temperatures not about the North Atlantic specifically where hurricane Irene was intensified.
The relationship between ocean heat content and ocean temperatures is still unclear because the flow of energy into the deep oceans is not measured or modeled well.
http://pubs.giss.nasa.gov/docs/notyet/submitted_Hansen_etal.pdf
“Improving observations of ocean heat content show that Earth is absorbing
more energy from the sun than it is radiating to space as heat, even during the recent solar
minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W/m2 during the 6-year period
2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global
climate change. Observed surface temperature change and ocean heat gain together constrain the
net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too
efficiently into the deep ocean and as a result underestimate the negative forcing by human-made
aerosols. Aerosol climate forcing today is inferred to be 1.6 ± 0.3 W/m2, implying substantial
aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific
origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to
understand future climate change. We conclude that recent slowdown of ocean heat uptake was
caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar
minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt
and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration
of the rate of sea level rise this decade.”
Stan
@48,
If ocean temperatures warm by 1deg C, the amount of water vapor available for precipitation should increase by about 6-7%. That is basic physics, and has been verified by observations of the actual behavior of the atmosphere.
http://www.agu.org/pubs/crossref/2008/2008GL035333.shtml
@ Eric (51)
There is no law (basic or otherwise) that firmly connects the SST with humidity or evaporation, much less the rainfall. The linked paper doesn’t state such a law either. They are working with observations.