radiative (solar-volcanic) forcing. The purple line shows the CO2 concentration (right axis). b, Shown are the global mean temperature (red), and the global mean precipitation intensity (blue) simulated in the forced run with the ECHO-G model. (p.p.m., parts per million.)
From the University of Hawaii ‑ SOEST, more modeling mania for the future.
New research shows complexity of global warming
Greenhouse gases versus solar heating
Global warming from greenhouse gases affects rainfall patterns in the world differently than that from solar heating, according to a study by an international team of scientists in the January 31 issue of Nature. Using computer model simulations, the scientists, led by Jian Liu (Chinese Academy of Sciences) and Bin Wang (International Pacific Research Center, University of Hawaii at Manoa), showed that global rainfall has increased less over the present-day warming period than during the Medieval Warm Period, even though temperatures are higher today than they were then.
The team examined global precipitation changes over the last millennium and future projection to the end of 21st century, comparing natural changes from solar heating and volcanism with changes from man-made greenhouse gas emissions. Using an atmosphere-ocean coupled climate model that simulates realistically both past and present-day climate conditions, the scientists found that for every degree rise in global temperature, the global rainfall rate since the Industrial Revolution has increased less by about 40% than during past warming phases of the earth.
Why does warming from solar heating and from greenhouse gases have such different effects on global precipitation?
“Our climate model simulations show that this difference results from different sea surface temperature patterns. When warming is due to increased greenhouse gases, the gradient of sea surface temperature (SST) across the tropical Pacific weakens, but when it is due to increased solar radiation, the gradient increases. For the same average global surface temperature increase, the weaker SST gradient produces less rainfall, especially over tropical land,” says co-author Bin Wang, professor of meteorology.
But why does warming from greenhouse gases and from solar heating affect the tropical Pacific SST gradient differently?
“Adding long-wave absorbers, that is heat-trapping greenhouse gases, to the atmosphere decreases the usual temperature difference between the surface and the top of the atmosphere, making the atmosphere more stable,” explains lead-author Jian Liu. “The increased atmospheric stability weakens the trade winds, resulting in stronger warming in the eastern than the western Pacific, thus reducing the usual SST gradient—a situation similar to El Niño.”
Solar radiation, on the other hand, heats the earth’s surface, increasing the usual temperature difference between the surface and the top of the atmosphere without weakening the trade winds. The result is that heating warms the western Pacific, while the eastern Pacific remains cool from the usual ocean upwelling.
“While during past global warming from solar heating the steeper tropical east-west SST pattern has won out, we suggest that with future warming from greenhouse gases, the weaker gradient and smaller increase in yearly rainfall rate will win out,” concludes Wang.
Citation:
Jian Liu, Bin Wang, Mark A. Cane, So-Young Yim, and June-Yi Lee: Divergent global precipitation changes induced by natural versus anthropogenic forcing. Nature, 493 (7434), 656-659; DOI: 10.1038/nature11784.
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Full paper here: http://www.readcube.com/articles/10.1038/nature11784
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Steven Mosher says:
February 1, 2013 at 7:54 am
“It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man.”
####
What does it take to convince a nonreasoning man?
Bruce Cobb says:
February 1, 2013 at 5:51 am
““Global warming from greenhouse gases”. Proof? It’s like assuming the earth is flat, and writing a paper based on it.”
If its a gas that is transparent to incoming solar but opaque to outgoing infrared (water vapor, CO2, ozone), it warms. If its a solid or liquid suspended in the atmosphere (cloud droplets, soot, aerosols) it cools. Trust me. If it were not so, we would be very cold indeed.
Mosher:
The difference is we actually do take airplanes (without all their expensive avionics) out and shoot them, then we shake the dickens out of them to see where they will break. Your whole “engineer” verses “skeptic” strawman was entertaining, but totally misrepresents the test and design processes used in aerospace. We actually do put models in wind tunnels with pieces missing to see how much destruction a plane can survive. We put everything that comes out of the computer models into a scale model and hit it with real aerodynamic forces to check. We even do that for Airliners. The FAA doesn’t like to sign off on something until we can show that we have tested the computer models against the REAL WORLD. Yes, we design virtually everything on the computer these days and we run millions of simulations in the computer to eliminate all the obvious errors, but then we make physical models and run them through the wringer to catch the things that computer models – no matter how complex, miss. Building an airplane is a 100’s of millions of dollars proposition, and we aren’t going to invest a penny into forging composites and aluminum into shape until we are pretty darn sure the thing isn’t going to wind up a test pilot’s death bed. Now about testing lithium-ion battery packs, I have no comment.
Mr Mosher, are you seriously suggesting that mathematical proofs are not science? This post-normal science stuff works really well for soft gooey sociology (and art) but is pure crap for the hard sciences. Now granted, GCM’s are a fine blend of hard physics and all those other gooey pursuits. But your insoluble problem appears to be an inability to recognize that many theories residing in various problem spaces within “climate science” are entirely capable of being discounted as outright wrong because the hard side of the domain is entirely falsifiable. And we then have the luxury of being able to discount the entire body of work because it is easily definable as pure bunkum. And this fine study falls squarely into that domain. The uncertainty levels of this study alone, ensures that it would only ever be laughed at in the schools of math and engineering (where truth, lie and unknown is very much definable).
Espen (February 1, 2013 at 2:50 am) wrote:
“I see one big problem here: They claim that the warming is stronger in the east Pacific than in the west – but as Bob Tisdale shows again and again – for several decades there has been no warming at all in the east Pacific.”
That’s a “problem”?? : ]
Actually, more of an opportunity …
If you put their theory together with Bob Tisdale’s observations, here’s what you’ll deduce:
The LACK of warming in the East Pacific indicates the TRUE anthro-warming signal.
I do not wish to interrupt the sudden – and welcome – ebullience from Steven Mosher on this thread. But my comment is in response to Mr Lynn a few hours ago. My friend, you really should not have mentioned Shakespeare on a thread about a climate modelling paper! This is what you caused me to write…
Blow, blow, thou modelled wind!
Our study does now find
Props for our platitude;
Warming’s Man’s fault, we mean.
Fingerprints can be seen,
At every latitude.
Heigh-ho! sing, heigh-ho! On with the green folly:
Our “science” is failing, but we love the lolly:
Then heigh-ho, the lolly!
These grants are most jolly.
Freeze, freeze thou modelled sky?
No! That would give the lie
To our well-crafted plot.
Children will never know
The sting of ice and snow!
It will be hot, hot, hot.
Heigh-ho! sing, heigh-ho! On with the green folly:
Our “science” is failing, but we love the lolly:
Then heigh-ho, the lolly!
These grants are most jolly.
This study has uncertainty levels larger than the national debt.
Airplanes are now analogous to planetary climate systems. I’ve seen some interesting ways to account for studies with astronomical uncertainties but that one takes the cake. If it were not Mosh, I would be laughing out loud. But I fear Mosh will have to retort in some clever sounding post-normal way.
Just remembered this discussion here:
http://wattsupwiththat.com/2009/11/29/the-medieval-warm-period-a-global-phenonmena-unprecedented-warming-or-unprecedented-data-manipulation/
May be helpful…
William H says:
February 1, 2013 at 3:04 am
Is this another attempt by the Chinese, who seem increasingly to be the authors of these ‘studies’, to dumb us down to the point that we don’t know which way is up any more?
William,
It’s great you noticed a glimpse of the trend that starts in the Universities. Check out and you’ll see that 50%-70% of grad students in the science and engineering departments of all major US Universities are from China and India.
I don’t mind this global warming. It was 70 degrees in Baltimore Wednesday, then overnite we got between 2-3 inches of rain! If it has been normal temps, we would have had 18-30 inches of snow! My back thanks you global warming!!! Oh wait, that was just weather wasn’t it?
Darn.
Another not too scientific study. This year : 2013, current CO2 concentration, 395, the lastest figure readable from your charts : 345 (’twas some time ago…). Everything else in the text is heavy on good reasons why, but rather vague when it comes to precise dates. If we stick to phenology, I can’t imagine seeing somebody plucking fruits from olive trees in Paris (France) a thousand years ago the way it is done on a regular basis nowadays.
January 2013 Sunspot number is SSN=62.9, 22 points up on the December 2012 (40.8).
Possible sign of the increased activity?
It doesn’t look like.
http://www.vukcevic.talktalk.net/SSN.htm
Polar field has retreated back to negative territory
http://www.vukcevic.talktalk.net/LFC6.htm
Despite assurances by Dr. Svalgaard this cycle (SC24) looks more like one of two centuries ago (peak around 1817), than one ‘a century ago’ with peak at 1918.
Dalton minimum is on cards (as the monochrome graph in the link above, suggested almost 10 years ago).
“global rainfall has increased less over the present-day warming period than during the Medieval Warm Period, even though temperatures are higher today than they were then.”
— What a baseless assertion.
Walt The Physicist says:
February 1, 2013 at 9:30 am
……
Not to mention all the micro-chips with built and preprogrammed codes to do things you never wanted or suspected. 🙂 (sarc off)
William H says:
February 1, 2013 at 3:04 am
Is this another attempt by the Chinese, who seem increasingly to be the authors of these ‘studies’, to dumb us down to the point that we don’t know which way is up any more? In none of these studies is there any practical way to test their hypothesis (i.e. WAG, without the S for Scientific)….
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
S stands for SILLY not scientific in SWAG, especially when talking of CAGW.
John West says:
February 1, 2013 at 3:26 am
John Marshall says:
”Will the Hawaii ‘scientists’ explain why a desert, very dry, is far hotter than a rainforest at the same latitude. According to the GHG theory the reverse should be true.”
Actually, GHG “theory” predicts that the desert would cool faster than the rainforest and it does….
>>>>>>>>>>>>>>>>>>>>>>>>>>>
The desert I looked at heated to a higher temp during the day and cooled to a lower temp at night. Over all the average temp in the desert was +8C warmer than the rain forest. What the water vapor did was even out the day/night temperature swings and provide net cooling.
Sleepalot @ur momisugly July 21, 2012 at 4:53 am pointed out the actual effects of the GHG water vapor on the temperature by comparing high vs low humidity. My comments expanding the idea:
Link 1
Link 2
Nothing beats looking at actual data.
Elizabeth says:
February 1, 2013 at 4:47 am
OT but maybe relevant. Has anybody noticed that lately a “Global Warming” search in Google news is getting less and less biased towards the AGW fanaticos? ie more skeptical stories appearing on MSM etc…..
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
It is part of the climb down since they KNOW darn well the temperatures have peaked and are on the way down. Now we just have to figure out what the next crisis will be that they blame on human kind so they can stampede us into the direction they want.
“The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary.” ~ H. L. Mencken
pochas says:
February 1, 2013 at 8:52 am
Bruce Cobb says:
February 1, 2013 at 5:51 am
““Global warming from greenhouse gases”. Proof? It’s like assuming the earth is flat, and writing a paper based on it.”
If its a gas that is transparent to incoming solar but opaque to outgoing infrared (water vapor, CO2, ozone), it warms. If its a solid or liquid suspended in the atmosphere (cloud droplets, soot, aerosols) it cools. Trust me. If it were not so, we would be very cold indeed.
Does it warm? or do the GHG merely retard the rate of heat and energy transfer – thus “keeping” us warm(er)?
vukcevic says:
February 1, 2013 at 10:42 am
Despite assurances by Dr. Svalgaard this cycle (SC24) looks more like one of two centuries ago (peak around 1817), than one ‘a century ago’ with peak at 1918.
SC24 looks very much like SC14, which had half a dozen peaks between 1905 and 1910, ~107 years ago. http://www.leif.org/research/SC5-14-24.png
Perhaps you should try to throttle back verbiage about things you don’t have a grip on.
Leif Svalgaard says:
February 1, 2013 at 12:06 pm
……..
SC 5, 14 and 24 compared
http://www.vukcevic.talktalk.net/SC5-14-24.gif
SIDC with no correction
Beauty is in the eye of the beholder.
pochas says:
February 1, 2013 at 8:52 am
Thanks for explaining the greenhouse effect. That really isn’t the issue, though. The issue is to what extent the increased levels of greenhouse gasses, primarily C02, have caused the recent warming. In theory, they should cause at least some, however the climate is a dynamic system, with negative feedbacks. That is to say, climate’s sensitivity to increased C02 doesn’t appear to be that great.
vukcevic says:
February 1, 2013 at 1:22 pm
SC 5, 14 and 24 compared http://www.vukcevic.talktalk.net/SC5-14-24.gif
SIDC with no correction
1: SC5 data was botched by Wolfer’s dubious ‘adjustment’ of the SSN in 1902. SIDC still reports those [wrong] numbers.
2: There is general agreement in the SSN ‘community’ that correction of the SIDC numbers must be made, so if you plot without correction you are behind the curve.
Beauty is in the eye of the beholder
So is, apparently, garbage.
Lew Skannen says:
February 1, 2013 at 2:42 am
No! Not complex at all. David Attenborough explains it.
Basically the climate is modelled by a green line and a yellow line. The green line is the climate without human produced CO2 and that is a rather trivial model because all it requires is the input of volcanoes and the sun … and a few hundred other parameters available here.
( http://wattsupwiththat.com/2012/02/19/crowdsourced-climate-complexity-compiling-the-wuwt-potential-climatic-variables-reference-page/ )
You then add in the effect of CO2 to this simple model and you get the yellow line.
Simple.
I think you forgot the convergence problem.
Bruce Cobb says:
February 1, 2013 at 1:25 pm
“In theory, they should cause at least some, however the climate is a dynamic system, with negative feedbacks. That is to say, climate’s sensitivity to increased C02 doesn’t appear to be that great.”
You’ve got that right. But stripping away the tech jargon, the 2 ppm per year continuing increase in CO2 had caused no increase in temperature for the last 15+ years, indicating that other factors are in aggregate at least as important and making CO2 only a contributing factor and not the dominant one as has been alleged by the IPCC.