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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peterg on February 1, 2013 at 5:12 am
“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.”
At 300w/sq m at the surface you’d think it would show up on a handheld ir thermometer when pointed at a clear sky. But it doesn’t detect anything, it reads under scale of less that -40F. It does however detect a short wave reflection of the Sun off the atm of max scale over +608F though.
I see my post ended up in a timely stop. I should have mentioned that the -40F reading was taken on a 35F day, and the thermometer read long wave ir from every surface it was pointed at. Including the bottom of clouds, except clear sky between where the Sun was, and the short wave reflection I mentioned.
Answer to Jens Bagh who said:
February 1, 2013 at 1:57 am
Please provide proof temperatures today are higher than during medieval period 900 -1200 BP.
I can prove that the temperature during 900-1200 BP was WARMER than today.
* ”Most of the Viking expansion took place during what scientist refer to as the dimatic optimum of the Medieval Warm Period dated ca, A.D. 800 to 1200 (Jones 1986: McGovern 1991); a general term for warm periods that reached chere optimum at different times across the North Atlantic (Groves and Switsur 1991). During this time the niean annual temperature for southem Greenland was 1 to 3°C higher than today.” Julie Megan Ross, Paleoethnobotanical Investigation of Garden Under Sandet, a Waterlogged Norse Farm Site. Western Settlement. Greenland (Kaiaallit Nunaata), University of Alberta, Department of Anthropology Edmonton. Alberta Fa11 1997, page 40
* One of the most common pollens found during the excavation of the Garden of Sandet was Cyperaceae. First of all. The farm called ‘Garden under Sandet’ came into permafrost in mid 1300’s. It wasn’t until 1990 it was possible at all to excavate the farm in Greenland. Cyperaceae, as well as Shephard’s-purse Latin: Capsella bursa pastoris (Distribution: Capsella bursa pastoris and willow (latin: Salix caprea) distribution: Salix caprea distribution was found in layer from the early days of the farm. None of these could have been there hadn’t it been warmer in 900-1400 AD. In other words during the period you refer to 900-1200 BP.
* Other sources those who beliefs that today is warmer should have read had they been trustworthy:
McGovern Thomas H., Bones, Building and Boundaries: Palaeoeconomic Approaches to Norse Greenland. “Sandnes(W51) Hall 72 m², Byre 84 m² and Barn 155 m²; and Anavik(W7) Hall ?, Byre 50 m², Barn 54 m² and Storage 38 m²”. [McGovern, Table 6 Floor-area of selected structures of farms of the Eastern and Western Settlements, page 213.]
You might not know but 5000 people lived in Greenland in the warm peak (more than 2-3 degrees higher than today) The example above is from one of many of the farms. All in all farms in Greenland during the period up to 1341 were larger and they had more animals stallplaces on each farm than the ordinary Scandinavian and northern Europe farms had.
I can give you numerous example from real facts that prove the Climate alarmist as wrong as can be. Unfortunatly for them they don’t seem to have had access to any well educated Systemprogrammer who had studied Mathematical Statistic, (I am from 1971 as well I have studied the subject and many more). Had they had that, they would have known that it’s not possible to draw conclusions from none correct information. Corrected values aren’t correct! Mind you one can’t take the fact that the Alarmist scholars haven’t shown full knowledge of Computer Science limitations and programming as a proof of them not having a good systemprogrammer close by their side …. 🙂
”There is a lot of energy that is out there that is not used for anything yet it is there,
How does one account for it?”
One accounts for it with the LAW of conservation of mass and energy.
Well beyond the obvious, do you have a better answer?
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.”
Yes, and he agrees with Paul Ehrlick that the global population MUST be significantly reduced..
Box of Rocks says:
”Well beyond the obvious, do you have a better answer?
The best accounting of Earth’s energy that I’ve seen:
http://jonova.s3.amazonaws.com/graphs/earth-energy-budget/stephens-earth-energy-balance-diag-crop.gif
It still leaves out several known energy conversions such as visible light to chemical energy (photosynthesis), which I would estimate at about 0.2 W/m2. So, if your point is that “climate science” hasn’t “accounted” for all the energy, then I’d have to agree, but that doesn’t mean the GHE is imaginary.
If there were no greenhouse effect it would not be sustainable for the surface to radiate 117% of SI to the atmosphere. Speaking of which, that 117% is SI is warming the water vapor and whatever few dioxides of Carbon from the bottom. I believe the models can be fixed but not by someone who thinks that warming the bottom of the atmosphere reduces the lapse rate. ” 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.”
Not scientists, attorneys.
MiCro says:
February 3, 2013 at 6:19 am
I did a bunch of reading last night at Dr Spencer’s blog, and the Long Wave IR is what’s warming the atm from the temp of Space to the -40F or so. Experiments in general measure the difference from surface temp to the sky temp as 10-20C depending on water vapor content. My reading was ~40C, but it was taken at near zero, so much of the water vapor was frozen out already. On a 12C day I saw a reading of ~ -35C, a 47C difference. My plan is to start logging IR temps, with surface temp and humidity on clear days.
You can see Black Body spectrum’s, and http://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Units=SI&Type=IR-SPEC&Index=1#IR-SPEC and http://webbook.nist.gov/cgi/cbook.cgi?ID=C7732185&Units=SI&Type=IR-SPEC&Index=1#IR-SPEC spectrum’s to compare long wave radiation spectrums, and see the area that is of interest is 14-15um, but remember that one hour Solar .5u IR would take 20 hr’s to radiate out at 10u, and 30 hr’s at 15u.
But also note, that surface records shows no trend in the annual change in the difference between daily temperature increase and the night time drop in temps.
By Global difference by Latitude