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.
=============================================================
Full paper here: http://www.readcube.com/articles/10.1038/nature11784
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Both Arctic and Antarctic ice isotopes say the Medieval Warming Period was warmer than the present. The greatest heat at present seems to be between the ears of tax-and-reg types.
John West says:
February 1, 2013 at 3:26 am
“Actually, GHG “theory” predicts that the desert would cool faster than the rainforest and it does.”
Yes, but don’t forget to mention that the GH gas in this case is water vapor, or the lack there of.
Let’s see .. they claim the atmosphere will produce less rain and be more stable. That completely refutes the claims of extreme weather. From now on when anyone tells you that climate change creates more extreme weather simply point them at this study and tell them they are denying peer reviewed science.
If they can use junk science to make claims we can certainly use junk science to refute them.
At “Using computer model simulations,…” I stopped reading. Why don’t these people just say “We don’t know.”?
My knee-jerk reaction to this story is not to heap scorn on it. It suggests a plausible mechanism for the climate stability of the last decade. In addition the study contradicts the alarmist predictions of catastrophic increases in rainfall, and favors the skeptic cause.
I would like to see how Liu et al account for the lack of a “fingerprint.”
Perhaps there is some subtle message here. Climate models with positive feedback would have to have enhanced evaporation and precipitation, and if this isn’t in the records, would have to be explained somehow. This study would suggest that CO2 does not create extra H2O vapor, so less positive feedback?
For mine, 300 hundred watts/m2 long range radiation from the atmosphere raises the surface temperature by 30 degrees K, so an extra 2 watts isn’t going to do enough to be noticed outside the measurement noise.
Here we go again. If the authors of the article wish someone to take their assertions and their model seriously then I am sure they will be willing to give us their global precipitation predictions.
If I was feeling generous then I might initially even accept some “projections” in lieu of predictions.
“Using an atmosphere-ocean coupled climate model that simulates realistically both past and present-day climate conditions….”
My eyes rolled so hard, my ocular muscles cramped and I’ll be seeing double for a week.
Climate Models are based on inaccurate and manipulated assumptions of chaotic systems not well understood, by grant-funded scientists that are paid to adjust the parameters to get a predetermined result so they can keep their jobs.
What could POSSIBLY go wrong with scenario?…
Ah, but “Using computer model simulations, the scientists . . . showed that global rainfall has increased less over the present-day warming period than during the Medieval Warm Period . . . ” See? It was evidence! It’s better than present-day “reality”; it’s a time machine! With a little tweaking, it will doubtless show us Will Shakespeare subcontracting out his plays to . . . Well, we won’t give it away; that’s for next week’s PR^ 2 (Peer-Revealed Press Release).
/Mr Lynn
At least they made a point of mentioning it is all a modelling exercise…
“…For the same global surface temperature increase the latter pattern produces less rainfall, notably over tropical land, which explains why in the model the late twentieth century is warmer than in the Medieval Warm Period (around AD 1000–1250) but precipitation is less…..”
And of course, Mann is the main source of the MWP being cooler than today, based on his weighted proxy sourced models…..
Science 2009 Vol: 326:1256-1260. DOI: 10.1126/science.1177303
Global signatures and dynamical origins of the little ice age and medieval climate anomaly
Mann, M. E.
Intriguing to see how few proxies are available stretching back to the the MWP, and how they are weighted, and how much ‘modeled cooling’ there is in areas where proxies aren’t available … http://www.sciencemag.org/content/suppl/2009/11/25/326.5957.1256.DC1/Mann.SOM.pdf
And the solar forcing has the usual problem that recent values are assumed to be significantly higher than around 1900, although solar activity now [and recently] is on par with what it was a century ago.
Any Study starting with the premise that current warming is GHG based is GIGO before it starts.
Two of the institutions named are Hawaii University and Columbia University, so I’m inclined not to believe that explanation. If I was looking for a conspiracy theory I would more likely guess it to be an attempt to influence China and their fossil fuel consumption, rather than the other way round.
Or possibly an attempt to ingratiate themselves with influential people in China.
That said, my pet theory, and null-hypothesis, remains one of gross general incompetence.
@ur momisugly John Marshall February 1, 2013 at 2:54 am
Will the Hawaii ‘scientists’ explain why a desert, very dry, is far hotter than a rainforest at the same latitude.
But a desert cools significantly at night, giving it a large Diurnal Temperature Range. So whilst its daytime temperature will be warmer (than a rainforest), its daily mean temperature may not be.
“Global warming from greenhouse gases”. Proof? It’s like assuming the earth is flat, and writing a paper based on it.
[ Konrad says:
February 1, 2013 at 2:36 am
This will be the coming meme, “it’s more complex than we thought.”. ]
My initial reaction exactly.
It’s more complex than we thought, and it’s going to be worse than we think.
Alan the Brit says:
February 1, 2013 at 3:02 am
(BTW just thought I’d ask, are you chaps & chappesses getting along alright in the colonies without us?)
Alan the Brit 😉
———————————
Actually Alan we could use some help but I don’t think your leader’s ideas are any smarter than Lisa Jackson’s.
She must have sold all of her oil stocks and invested in carbon credits or like your leaders invested in marine hazard bird thrashers.
I wonder if all the major pension plans in the world are heavily invested in a “green future”?
cn
“we suggest that with future warming from greenhouse gases, the weaker gradient and smaller increase in yearly rainfall rate will win out”
Okay, fine. And what do they predict?
“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.
============
Rubbish. That directly contradicts the atmospheric “hot spot” predicted by all climate models. Nowhere is it predicted that AGW will cause the surface to warm faster than the atmosphere.
One of the main predictions of AGW is the GHG warms the atmosphere first, then the surface warms as a result of the lapse rate tying the atmosphere to the surface.
In contrast, it is solar heating that heats the surface first, then the atmosphere warms. Thus one way to detect if warming is due to GHG or solar influences is to study if the atmosphere lags the surface of the surface lags the atmosphere.
****
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.
****
Mule-fritters. Tell that to the Vikings and many others…
And they know how much rain fell around the world during the MWP how?
It is really worth going back to assess Mann’s original contention that the MWP was ‘cooler than the present’ (of course, he has to rename it the MCA, the Medieval Climate Anomoly, as otherwise the whole thing would fail the Orwellian test).
Available here: (needs a log in – no cost) Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly. Michael E. Mann, Zhihua Zhang, Scott Rutherford, Raymond S. Bradley, Malcolm K. Hughes, Drew Shindell, Caspar Ammann, Greg Faluvegi, Fenbiao Ni
http://www.sciencemag.org/content/326/5957/1256.short
http://www.sciencemag.org/content/326/5957/1256.full.pdf
Note Figure 2 – the top figures showing the temperature anomaly map of the world for the MCA (compared to the 1961 to 1990 period) ..and the weighted proxies on the right…to me it is an incredible construct: Note all the blue (cooler than recent times) on the map.
Starting in northern America we see a cluster of proxies – by the temperature anomaly map, all apparently warmer than now, except for one cooler site. Down to the Caribbean … neutral, but heavily weighted..
Peru, Ecuador, looks like it was warm there…. back up to Greenland … a very warm spot…, across to Europe, only two proxies, one heavily weighted, but both warmer, across to northern Russia …one isolated proxy with an isolated warmer spot … to central China, there is a cooler spot …then head a bit east in China..another very hot spot…then all the way down to Tasmania and New Zealand – Tasmania is cooler, NZ is warmer than now…… Back to Africa, 3 proxies, one cooler (and heavily weighted) and one very lightly weighted and warmer, and one neutral…
Then look at all the modeled cooling on the map … right across central Asia, based on 4 proxies (!!), all of which were warmer except one… ALL of the Southern Ocean, the southern Indian Ocean, and southern Atlantic oceans were supposedly much cooler, (based on Tasmania, and three proxies in Africa?!!) All of the eastern Pacific is shown as cooler, … based on a string of proxies in the western Americas, which were mainly warmer, and perhaps eastern China ..warmer also?
Now I do appreciate the vast effort and detailed measurements and complicated science which have gone into this effort, but to me it is rather like building an intricate full scale model of a Boeing 747 with Lego blocks (a truly mighty effort indeed) and then selling flight tickets to London.
Joe Public says:
February 1, 2013 at 5:46 am
@ur momisugly John Marshall February 1, 2013 at 2:54 am
Will the Hawaii ‘scientists’ explain why a desert, very dry, is far hotter than a rainforest at the same latitude.
=========
But a desert cools significantly at night, giving it a large Diurnal Temperature Range. So whilst its daytime temperature will be warmer (than a rainforest), its daily mean temperature may not be.
=========
As well, the rainforest air contains significantly more energy than the desert at the same temperature due to water vapor. Thus it is meaningless to talk about temperature without also talking about humidity. 100F at 0% RH is much different than 100F at 100% RH. Something that makes something called “average global temperature” completely meaningless.
You cannot average the temperature between two places with different relative humidity and arrive at a meaningful result. This is especially true when considering land temperatures. Ocean temperatures are somewhat more meaningful because the humidity is more constant.
So when the Sun heats thangs up without the aid of greenhouse gases, the air is cranky, but when greenhouse gases fouls that process up, the air becomes nice’n peaceful like. Dang. Can’t be have’n that now can we, cuz it be opposite of the current talk’n points for political action. But then I s’pose Ph.D. types don’t much worry ’bout us flat Earthers notice’n the contradiction.
lsvalgaard says:
February 1, 2013 at 5:31 am
although solar activity now [and recently] is on par with what it was a century ago.
===========
And temperatures have not increased for 16 years and counting, in spite of massive increases in CO2 as China and India have industrialized.
Coincidence? Maybe. But it certainly indicates that CO2 is not the main driver of temperature. We should have seen a massive increases in temperature over the past 10 years due to industrialization and land use changes. It hasn’t happened, contrary to the predictions of the majority of climate scientists. Hansen, Mann, Jones, the IPCC, they got it dreadfully wrong and billions in taxpayer money have been wasted in the process.
When a theory fails to predict correctly, it is a failed theory. All that is required is a single contradiction to disprove a theory. This is the very heart of science and the scientific method. Any example that contradicts the theory is proof the theory is wrong.
This is completely Ignored by consensus climate science because climate science is not a science any more than political science is a science. Climate science is the political process of collecting confirmations for a belief, while ignoring contrary evidence.