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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Volcanism, the unknown forcing. Nobody knows what the average flux is from the volcanic core out to space, how it varies temporally and spatially. It could easily equal other forcings but we have a paucity of measurements. Pity the PR release doesn’t go further on what they mean by volcanism.
Please provide proof temperatures today are higher than during medieval period 900 -1200 BP.
“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.”
I can understand proxies for temperature during the MWP – a subject obviously beyond the grasp of Mann and his ‘maths’, but a proxy for rainfall? Rainfall records were not particularly good 800-1,000 years ago!
So, just make it up as you go along, just like most ‘climate science’.
Are temperatures higher now than they were in the Medieval Warm Period?
“Using computer model simulations -” … “Our climate model simulations show -”
I feel sorry for climatologists.
The climate is big and slow, so they can’t test their theories with experiments on the physical universe like proper physicists do. Instead they have to live in “The Matrix” and do all their science in a made-up virtual world.
Now, if we could harvest their energy while they were in there…
This will be the coming meme, “it’s more complex than we thought.”. The new strategy will be managing the walk back. Sceptics should turn and assault through. After this tiresome and sorry season of “The great global warming caper”, does anyone really want to sit through the same fellow travelers performing “Biocrisis! Biocrisis! ” or “Sence and Sustainability”? In the age of the Internet, the recommendation from Sun Tzu “always leave your enemy a path of escape” is not practical. A number of those that supported the “cause” are likely to experience significant upset in the coming year. I feel it is better to get it over quickly, than draw the end out.
“Of course, I am not suggesting that a more stable atmosphere can in any way imply that more extreme weather events are less likely”, he forgot to add.
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.
Thats the fun part of climate sciences they don’t understand. If you use false data tho make a model you can only get a false model. This one is all so heavy hockestickt by saying that now its warmer then in the MWP it’s simply not warmer so the hole thing is a peace of grape.
Confused. It says that the whole globe never gets more than 3mm of rain a day (in the figure). How is that possible?
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.
As soon as GHG’s are mentioned we know that the rest is rubbish. The GHG theory is not built on science it violates both 1st and 2nd laws of thermodynamics so cannot happen. The sun is the ONLY heat input into the climate system.
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.
It is about time these people got out of their cosy rooms and looked at reality.
As for warming: if you click on WUWT’s World Climate Widget, for UAH an anomaly of minus 0.01 degree Celsius is displayed for January 2013, another 0.2 degree down from December 2012.
I wonder if and how the modelists can link this to increasing CO2 …..
PocketOED1925:
Model, to fashion after, a representation of thing or object. to work into shape.
Simulation, to feign, pretend, wear the guise of, or act the part of, shadowy likeness or mere pretence, unreal thing.
Representation, work of art portraying something, calling of attention to something, place likeness before, make out to be.
Remember you Virginian Colonials et al, these are not my words, but theirs!!!! Just one tiny wee flaw in the paper, it is based on the somewhat arrogant presumption that they know all there is to know about climate science, what drives it, what influences are major or minor, etc.
(BTW just thought I’d ask, are you chaps & chappesses getting along alright in the colonies without us?)
Alan the Brit 😉
But today the Sydney Morning Herald reported on yet another study from the University of Adelaide saying that rainfall intensity will increase with global warming…
http://www.smh.com.au/environment/climate-change/rainfall-intensity-to-increase-with-global-warming-study-20130201-2doro.html
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). Just the “computer model says so, so it must be so” scenario.
I can now say that I have lost what little ‘faith’ I had left in the pseudo-science of climatology.
On informing my bank manager that my computer (Excel) says I have more money than the monthly statement says, his response was “My computer says ‘No’!”. Turns out, the bank’s computer had made a serious error. It was contributing lots of warmth to the atmosphere while producing vast errors in output, due to errors in input. The climate modelers could learn a lot from my bank.
So very many weak links it defies belief that any two hold together at all, never mind form a chain. My skept-o-meter is pegged.
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.
IMO, this “paper” is just laying the foundation of explaining away the failed predictions of massive positive feedbacks from warming. Basically, they’ll be able to say “we didn’t know GHG forcing and solar forcing were different wrt water vapor / clouds (precipitation)” and go on being alarmist on something else like ocean “acidification”.
Where did this snippet of information come from?
What could have caused the allegedly localized and very warm period in Europe and left the rest of the planet alone? Now, here are the ‘localized’ effects of this period from the Mann himself. I accuse temperature of several centuries of discrimination. 😉
Just another climate model study. No basis in reality.
Here is the longest instrumental precipitation record fro England&Wales since 1766:
http://climexp.knmi.nl/data/pHadEWP_monthly_qc_mean1a.png
Please show me any foot print of “greenhouse gases forcing” in it. These are hard local data, no questionable proxies or, alas, computer models.
Wilt, I think you read the Jan 2011 figure, Jan 2013 isn’t out yet.
“Global warming – more complex than we thought”
[snip . . when commenting try and include some useful content . . mod]
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…
Correction: Steveta_uk you are right, the number on the climate widget refers to January 2011 (by the way it might be time to update the data that are displayed when clicking on the widget). Sorry for the mistake.