Heat, Not Just Rainfall, Plays into New Projections
Increasing heat is expected to extend dry conditions to far more farmland and cities by the end of the century than changes in rainfall alone, says a new study. Much of the concern about future drought under global warming has focused on rainfall projections, but higher evaporation rates may also play an important role as warmer temperatures wring more moisture from the soil, even in some places where rainfall is forecasted to increase, say the researchers.
The study is one of the first to use the latest climate simulations to model the effects of both changing rainfall and evaporation rates on future drought. Published this month in the journal Climate Dynamics, the study estimates that 12 percent of land will be subject to drought by 2100 through rainfall changes alone; but the drying will spread to 30 percent of land if higher evaporation rates from the added energy and humidity in the atmosphere is considered.
An increase in evaporative drying means that even regions expected to get more rain, including important wheat, corn and rice belts in the western United States and southeastern China, will be at risk of drought. The study excludes Antarctica.
“We know from basic physics that warmer temperatures will help to dry things out,” said the study’s lead author, Benjamin Cook, a climate scientist with joint appointments at Columbia University’s Lamont-Doherty Earth Observatory and the NASA Goddard Institute for Space Studies. “Even if precipitation changes in the future are uncertain, there are good reasons to be concerned about water resources.”
In its latest climate report, the International Panel on Climate Change (IPCC) warns that soil moisture is expected to decline globally and that already dry regions will be at greater risk of agricultural drought. The IPCC also predicts a strong chance of soil moisture drying in the Mediterranean, southwestern United States and southern African regions, consistent with the Climate Dynamics study.
Using two drought metric formulations, the study authors analyze projections of both rainfall and evaporative demand from the collection of climate model simulations completed for the IPCC’s 2013 climate report. Both metrics agree that increased evaporative drying will probably tip marginally wet regions at mid-latitudes like the U.S. Great Plains and a swath of southeastern China into aridity. If precipitation were the only consideration, these great agricultural centers would not be considered at risk of drought. The researchers also say that dry zones in Central America, the Amazon and southern Africa will grow larger. In Europe, the summer aridity of Greece, Turkey, Italy and Spain is expected to extend farther north into continental Europe.
“For agriculture, the moisture balance in the soil is what really matters,” said study coauthor Jason Smerdon, a climate scientist at Lamont-Doherty. “If rain increases slightly but temperatures also increase, drought is a potential consequence.”
Today, while bad weather periodically lowers crop yields in some places, other regions are typically able to compensate to avert food shortages. In the warmer weather of the future, however, crops in multiple regions could wither simultaneously, the authors suggest. “Food-price shocks could become far more common,” said study coauthor Richard Seager, a climate scientist at Lamont-Doherty. Large cities, especially in arid regions, will need to carefully manage their water supplies, he added.
The study builds on an emerging body of research looking at how evaporative demand influences hydroclimate. “It confirms something we’ve suspected for a long time,” said Toby Ault, a climate scientist at Cornell University, who was not involved in the study. “Temperature alone can make drought more widespread. Studies like this give us a few new powerful tools to plan for and adapt to climate change.”
Rainfall changes do not tell the whole story, agrees University of New South Wales researcher Steven Sherwood, in a recent Perspectives piece in the leading journal Science. “Many regions will get more rain, but it appears that few will get enough to keep pace with the growing evaporative demand.”
The authors have made all their data and calculations public available on a supplementary website.
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“The study is one of the first to use the latest climate simulations to model the effects…” Oh, another model. That’s all right then.
You have to twist yourself into a pretzel to understand that more rain means more drought.and warming causes cooling.
It’s known the MWP was warmer than it is now. Surely the weather of the time was
reasonably well documented, along with crop yields, floods, droughts and all those
other cool things global warming is supposed to cause …
Why isn’t the historical record being closely scrutinised?
Hmm…I see it all more clearly…
More wet/dry/hot/cold/drought/flood/night/day/VC and bar…..That and our cheeldren just won’t know what snow is either.
Oh God, the polar bears too……….
I get to say “It’s even worse” first….
“The study is one of the first to use the latest climate simulations to model the effects of both changing rainfall and evaporation rates on future drought. “
As someone said, the output of an unvalidated model is an illustration of somebody’s hypothesis; it is not observational data. Regarding runs of unvalidated computer models as ‘experiments’ seems to be one of the characteristics of so called ‘climate science’ that is not regarded as acceptable in other fields.
Even if models can reproduce past climate, this is not (as is often claimed) validation of such models. It is the fallacy, recognized at least since early 1970’s in research on pattern recognition systems, of ‘testing on the training data’. If a model could not successfully reproduce past climate then it would obviously be a complete failure. However, reproducing past climate does not confirm the correctness of the model and its ability to predict future climate reliably – notwithstanding such claims by the UK Met Office.
I can produce a simple spreadsheet model that reproduces past climate with complete accuracy but which has no capability whatever of predicting future climate.
P.S. ……………..
“First, I asked Stephen Belcher, the head of the Met Office Hadley Centre, whether the recent extended winter was related to global warming. Shaking his famous “ghost stick”, and fingering his trademark necklace of sharks’ teeth and mammoth bones, the loin-clothed Belcher blew smoke into a conch, and replied,
“Here come de heap big warmy. Bigtime warmy warmy. Is big big hot. Plenty big warm burny hot. Hot! Hot hot! But now not hot. Not hot now. De hot come go, come go. Now Is Coldy Coldy. Is ice. Hot den cold. Frreeeezy ice til hot again. Den de rain. It faaaalllll. Make pasty.”
http://blogs.telegraph.co.uk/news/seanthomas/100222487/when-it-comes-to-climate-change-we-have-to-trust-our-scientists-because-they-know-lots-of-big-scary-words/
For me this is consistently the funniest pi**-take I have ever seen over many years now….
I also would like to draw attention to the little little caption under the main pic…..Icing on the cake.
“The study is one of the first to use the latest climate simulations”
Rubbish in, Rubbish out…
It is April fools day…
Admad says:
April 1, 2014 at 12:49 am
“The study is one of the first to use the latest climate simulations to model the effects…” Oh, another model. That’s all right then.
_______________________
Beat me to it.
I like the ‘fire’ burning on the horizon in the US corn belt picture at the top.
Clearly this is what we are to expect when denialists are met with the wrath of the climate gods for not taking seriously the teachings of the climate model bible.
We must pay penance and bow down before the lords of the IPCC.
Reblogged this on We have no Secrets and commented:
Third of the earth? How does one human fathom? Impossible to truly know.
I dont know why they keep talking about what will happen in the warming world, temperatures are not going up!
use the latest climate simulations
Oh. Never mind.
Is this an April Fool’s joke?
If the surface evaporation increases, won’t that just draw more water from the subsurface?
Bring it on, I have a lot of laundry to dry.
Sad had the new IPCC has gotten everyone panicked about the future a again. I see a lot of chatter amoung my friends and elsewhere that we are all doomed. Yet nobody is talking about selling their cars and having the power company shut off their electric, so deep down they mustn’t really believe it, mustn’t care, or think it’s someone else’s problem.
So the land will dry out more quickly than the extra rain falls. How does that work? Will there be an ever growing lake in the sky. I always thought what goes up must come down.
THE STUDY, THE FIRST TO USE THE LATEST CLIMATE SIMULATIONS…..
That remark trashes the entire report.
When will they ever learn that climate models and simulations at this stage have nothing to do with the real world.
We’re recycling BS again. I’m getting bored.
At the ever present risk of becoming an utter bore……………………Pocket Oxford English Dictionary, 1925:Simulate/Simulation, feign, pretend, to have or to feel, wear the guise or act the part of, counterfeit, having the appearance of, shadowy likeness or mere pretence of unreal thing! Don’t shoot the messenger, I didn’t use the words, they did!!!!!! Just saying. 🙂 AtB. (BTW, how are you Colonials getting along without us? Doing ok? Muddling through?)
BNenjamin’s basic physics seems not to include the laws of thermodynamics. Funny that.
Why should warm be dry ?
http://youtu.be/8ADbax8Dk0Y
(http://scienceblogs.com/gregladen/2014/03/01/a-letter-from-john-holdren-regarding-roger-pielke-jrs-statements/) :
“Similarly, long-term trends (1925–2003) of hydrologic droughts based on model derived soil moisture and runoff show that droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the U.S. over the last century (Andreadis and Lettenmaier, 2006). The main exception is the Southwest and parts of the interior of the West, where increased temperature has led to rising drought trends (Groisman et al., 2004; Andreadis and Lettenmaier, 2006).”
Hasegawa et al. 2013., Drastic shrinking of the Hadley circulation during the mid-Cretaceous Supergreenhouse (http://www.clim-past.net/8/1323/2012/cp-8-1323-2012.pdf). In this work it was found that as a result of a strong warming, instead of Hadley circulation has developed Farrell circulation – a warm temperate climate zone – with dominant maritime climate (in this climate the number of areas with periodic and constant drought, drastically decreases).
(http://www.sciencemag.org/content/330/6006/957.abstract) Jaramillo (2010, – 28 coauthors): “Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event.”
“There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to SPECULATIONS that tropical ecosystems were severely compromised by heat stress.”
“We know from basic physics that warmer temperatures will help to dry things out (…)”
– again we can clearly notice that the atmosphere physicists know very little about climate change …
I wonder if they ran the model to predict conditions during the Jurassic period ?
ie: inputs of CO2 = 3000ppm, Temp = 22 Deg C.
Killing 2 birds with one stone:- Desalination plants ,thousands of the buggers on coast lines everywhere ,water transported to dry areas .
Over (a very long) period of time , sea levels fall and more arable land is produced ,deserts turned into gardens.
Should it ever become necessary I am pretty sure that man can adapt to just about anything ,well apart from being bored to death by warmista ballerinas doing the dying swan.