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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mem says:
February 1, 2013 at 3:04 am
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
=======
Global warming predicts that rainfall will both increase and decrease. Thus any change in rainfall is evidence of global warming. If rainfall remains the same it is evidence of pent up rainfall, that can be expected to increase or decrease in the future due to global warming.
Here is a wiki on a method at least as accurate:
https://en.wikipedia.org/wiki/Haruspex
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.”
I thought that the top of the atmosphere always had and always will have the same temperature.
Didn’t know we were warming space too!
They’ve been telling us to expect MORE rainfall as a consequence of global warming. Indeed, it is now required in the UK for developers to include increased precipitation in their flood mitigation reports. If they now say, “sorry, we were wrong about that – you should use LESS precipitation,” changing their story from one year to the next, it gives the impression that the science is anything but settled, or that they’re talking out of their rear ends.
Warmer today than the MWP? Dr.Liu, your the Mann!
John Marshall,
“explain why a desert, very dry, is far hotter than a rainforest at the same latitude.”
I would say (just guessin’ here), that the rainforest is less hot than the desert because it is mostly covered in dense cloud, which reflects sunlight back into space, while the desert has clear blue skies, and so receives much more insolation.
Can you explain why the desert gets very cold at night – much colder than the rainforest does at night?
Silly science deserves a silly answer, therefore…
My computer model says Wang is Wrong.
lsvalgaard says:
February 1, 2013 at 5:31 am
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.
So what has changed since a century ago
There is very little of the global warming in the Equatorial region, where the TSI is the most significant factor, in contrast the greatest anomalies come from the poles, where the TSI input is very much more limited. Further more the largest temperature anomaly comes from the Arctic region itself
http://www.vukcevic.talktalk.net/AGT.htm
So if the TSI was more or less constant there are only two other alternatives that might effected the higher latitudes of the N. Hemisphere:
– Rise in CO2, but as it was shown many times CO2 was high and even higher in the past
– Changes in the Arctic as the engine driving the polar jet stream
http://www.vukcevic.talktalk.net/Arctic.htm
Because Greenland is so much greener today than when the Vikings colonized it.
ATTEMPTS to simulate realistically, and that’s if we give them the benefit of the doubt, but their unscientific assertions make that difficult. This kind of “we’ve got it nailed” talk is a stylistic mark of the current results-oriented “consensus.”
Their thesis is obvious enough, and doesn’t seem to be anything new:
GCR-cloud theory and UV-shift-cloud theory follow a similar path, seeing the change in cloud cover as modulating the amount of direct insolation of the surface, as opposed to GHG theory with its predicted (but unobserved) upper troposphere hot spot.
But given the way these guys talk they must be using the standard GCMs, which assume that solar variation has one fortieth the forcing effect of CO2 over the 1850-2010 calibration period, so their modeling would have nothing to add to the simple logic their premise.
“It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man.”
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.”
Indeed so, Steven.
But does it look like the failure of their argument and the distinct lack of proof is swaying them from their mission?
They reported:
“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.”
Peter Miller says (so many others agree): So, just make it up as you go along, just like most ‘climate science’.
I agree Peter–
1. apparently they did not udnerstand that the models aren’t predicting anything particularly well.
2. It’s raining quite a bit now–many warmists are claiming way more rainfall becasue of GHG warming–so how would they know it has increased less????
“Places now wetter than the historical average include Northern Europe, eastern North and South America, and northern and central Asia. Northern Scandinavia and South and North Korea recorded precipitation increases of 3-15 percent per decade between 1979 and 2005” http://www.climatehotmap.org/global-warming-effects/rain-and-snow.html
“…an 8 percent increase in rainfall stemming from global warming ” http://www.stanford.edu/~moore/Boon_To_Man.html
3. And they didn’t get the mssage that it was really warmer in MWP??? At least in the NH.
“Once again the fear-mongering hoards of lay-climatologists are denouncing the importance of the Medieval Warm Period (MWP), or Medieval Climate Optimum as some refer to it.” http://www.thegwpf.org/doug-hoffman-medieval-warm-period-under-attack-again/
Geeze!
PS–to Alan the Brit–I like “chappesses” but to answer your questions–no, not alright, after winning our independence so long ago, we are now going back to Imperialsim.
ferd berple says:
February 1, 2013 at 6:51 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.
It also indicates that the Sun is not the main driver
vukcevic says:
February 1, 2013 at 7:19 am
So if the TSI was more or less constant there are only two other alternatives
Shows your lack of imagination [or knowledge].
Mosh
Here’s the rest of the quote;
‘…With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape: they have to face the problem of a cosmic beginning.”
Have you suddenly got religion or something?
tonyb
Very nice, I see desperation, we need to get rid of the medieval warm period.
Some evidence as to how those viking artifacts coming out from under the ice got there, with those cooler than today temperatures would be nice.
One glance gave me the value of this paper, it boils down to,assuming that the hockey stick is true,therefore..
And the proxy for rainfall?
Looks a lot like only the useful idiots are still publishing in the climatology world..
Meet the new symbol for model predicted alarmism. http://www.bozemandailychronicle.com/news/environment/article_7b5f0760-6c2c-11e2-ab77-0019bb2963f4.html
The commenters who note that this seems incompatible with the extreme weather meme have my sympathy. Could it be that sensitivity (temp change per unit “forcing” change) is higher for solar than GHG’s? Perish the thought…
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.
===========================
So they are saying global rainfall has been static for the past 16 years
Patrick says:
February 1, 2013 at 5:04 am (Edit)
At “Using computer model simulations,…” I stopped reading. Why don’t these people just say “We don’t know.”?
#################
since you cannot do controlled experiments on the planet, you have two options as an observational scientist ( climate science is an observational science and not a labratory science )
1. Shrug your shoulders, and say “we can only describe the past and say nothing about the future” ( opps you are a historian not a scientist)
2. Make predictions about the future based on
a) statistics of the past
b) models.
The other subtle aspect of this is that one always implies “we dont know” when one puts uncertainty figures on predictions. In one sense science never knows, it knows as Feynman would say only what is more likely and what is less likely.
I’m also reminded of the aerospace engineers who I worked with.
Skeptic: “how many gs will the plane take?
Engineer: our models say 9gs, but we build in a 50% safety factor
Skeptic; a model? a model? why don’t you just say you don’t know?
Engineer: Well, because its my job to make the best estimate I can based on the best understanding we have and the best tools we have. I know my estimate will be wrong, but,
we learn and progress. That’s why we have a safety factor. After we build the plane we will
put it in a jig and shake it and bend it until it breaks and hopefully improve the models.
Skeptic: can the plane survive being shot by another plane?
Engineer: We’ll COVART says we have a high probability of surviving.
Skeptic; COVART?
Engineer: yes we model the survivability of aircraft to threats
Skeptic; model? model? why dont you just say you dont know/
Engineer: well, we know somethings better than others. Its incomplete knowledge but we
can identify problems and try to fix them. An estimate is better than shrugging
your shoulders and saying you dont know.
Skeptic: Just shoot the plane. test it.
Engineer: yes of course we do live fire to test it, but you cannot test all possibilities. Maybe we take 5 F-18s out to the desert and do live fire. Do you know what that costs? There is no way we can experiement with every bullet and every condition, so we have to model.
in some sciences you cannot afford the test and you cannot control the test conditions.
So, you have a choice:
1. head in the sand. we know nothing.
2. Our best reasoning ( modelling ) says the following.
Folks interested in live fire can see this
http://jaspo.csd.disa.mil/archives.html
Have you suddenly got religion or something?
tonyb
#############
tony, religion? no. But you’d be surprised the places you find interesting forms of argument.
I read everything.
‘But does it look like the failure of their argument and the distinct lack of proof is swaying them from their mission?”
there is no proof in science and folks who ask for proof need to unfool themselves and read some feyman. Science deals with the likely and the unlikely. proof deals with the possible and impossible.
Sorry to be a stickler for the details about this, but its important
Mosh
You read everything? Even Anna Karenina and Jude the Obscure?
tonyb
Steven Mosher says:
February 1, 2013 at 8:20 am
“The other subtle aspect of this is that one always implies “we dont know” when one puts uncertainty figures on predictions. ”
That’s why climate scientists run their models hundreds of times so they can in hindsight point to the one model run that resembles reality the most and say “We told you so”.
Like this climate scientist from Switzerland.
http://notrickszone.com/2013/01/31/yellow-science-renowned-climate-modeller-now-claims-temperature-stagnation-is-actually-evidence-of-warming/
And that’s why I would say, fire the lot and don’t give them one more dime; we can’t afford it and they are of absolutely no use.
The IPCC, Steven, BTW, has the political mission of researching the effects of antopogenic global warming. They don’t have the mission of asking themselves whether AGW is real, and they therefore do not add the “we don’t know”. They KNOW; it is their mission statement.
Fire the lot.
Jens Bagh says:
February 1, 2013 at 1:57 am
Please provide proof temperatures today are higher than during medieval period 900 -1200 BP.
###
Mann wrote an oft’ quoted paper on this in 2009, so you know its just got to be true.
Oh, come on people! Deserts heat and cool faster than rain forests because of the specific heat of dry air vice moist air. 1 degree (C or F your choice) change in temperature takes a lot more energy in moist air than dry. Once again people are conflating energy with temperature. Energy is the key to all of this argument. Boltzmann curves are about how fast something loses energy at a specific temperature; specific heat tells how much change of temperature that energy flow will cause in a particular medium. Climate science doesn’t seem to take that into account very often.
I know almost everyone reading at this site knows that bit of information, but I had to get it off my chest. There, I feel better already!