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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“We know from basic physics that warmer temperatures will help to dry things out”
Okay actually I believe temperature differential in comparison to humidity and direct sunlight dry things out. Access to large bodies of water etc… Second. If this were to be true that it wold ‘dry things out faster’ then that would lead to more cloud cover, this in turn would lead to more rain and less sunlight striking the earth etc. you know basic physics stuff… Right?
In the warmer weather of the future, however, crops in multiple regions could wither simultaneously, the authors suggest.
What is exactly causing the “extra warmth” anyway?
My observations reveal that usually a high pressure ridge/ Omega block in the atmosphere usually are the atmospheric phenomenon associated with droughts. Just look at he pacific NW. A large blocking high over has produced ‘record’ warmth and drought in that region.
Same thing happens on the high plains. A high forms over Texas and does not move for weeks.’
They all need to go back and define where the extra warmth came from and why.
_Jim
I want to open the eyes of those who look and do not see.
http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t100_nh_f00.gif
So weak magnetic field of the sun abolish all models.
Their cherished Warmist ideology is in trouble, and they know it. So, they are doing the only thing they know how, in a desperate effort to prop it up, and that is to follow the infamous Stephen Schneider (of Stanford) 1988 edict (I’ve bolded the key part):
“On the one hand, as scientists we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but – which means that we must include all doubts, the caveats, the ifs, ands and buts. On the other hand, we are not just scientists but human beings as well. And like most people we’d like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climate change. To do that we need to get some broad based support, to capture the public’s imagination. That, of course, means getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have. This “double ethical bind” we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both.”
That final line, “I hope that means being both” has, I guess, sometimes been left off when the quote is being used, and to Schneider’s twisted way of thinking, it somehow makes everything he said before alright. It most certainly does not. What he’s essentially saying is that he hopes scientists don’t have to lie, which would be the only scenario where they could be both effective and honest.
So, here we have “scientists” dutifully offering up scary scenarious, truth be damned, in order to capture the public’s imagination and continue to be “effective”.
These are not scientists at all, but mouthpieces for the Cause.
I wonder if they have taken into account the overuse of the Ogallala Aquifer. This has been in use for farming in the USA since it was discovered. It is expected that it will be emptied out eventually, when that happens there will be a drought, man made? Yes, AGW ? No
http://en.wikipedia.org/wiki/Ogallala_Aquifer
re: ren says April 1, 2014 at 5:25 am
I want to open the eyes of those who look and do not see.
Maybe you are not aware that industry is already ‘aware’ (of the potential impact of geomagnetic disturbances on a ‘modern’ society)?
For instance, see: the
PJM Manual 13, Emergency Operations page 51, titled “3.7 Geo-Magnetic Disturbances” as to how power transmission ops (operations) would handle this.
In any case, the ‘public’ needs to be prepared for a variety of disasters, both man-made and natural, including tornadoes, earthquakes, wild-fires, floods, etc., depending on where they live and the time of year. All this falls in the category of being prepared (part of the BSA motto – no?)
Various people with different skills can also ‘help out’ by being prepared to help in different ways, including emergency communications, via ham radio, for instance, something I have been involved with a different levels from time to time (via Radio Amateur Civil Emer. Service, and Amateur Radio Emergency Service® (ARES) with skywarn wx spotting).
Maybe this is something you might (or should) look into?
http://www.arrl.org/emergency-communications-training
.
While doing my searches I cam across this little nugget. It must play havoc with the models.
and this
Booga-booga.
Ooga-booga-booga.
Exactly! Bingo! They keep telling us it’s the hottest evaaaaah since 1975. Unprecedented global temperatures blah, blah, but they keep it restricted to the distant future. They will argue that these changes will take time BUT they keep telling me that the changes are happening now, it’s there for everyone to see. Funny that.
And Godzilla could grow out of a little island lizard exposed to radiation and attack New York, too.
Since temps have not done anything unusual, dangerous or unprecedented, I think we can file this bit of poorly written climate porn in the waste can, that has long been over flowing with hype, fear, and deception just like this bit of rent seeking tripe by Benjamin I. Cook,Jason E. Smerdon,
Richard Seager, and Sloan Coats.
Here is what the IPCC faces. It has to make decisions between which models to cherrypick and which ones don’t fit the story of gloom.
The scientific references in this thread show that the study in the post above proclaims a familiar message. Even though warming hasn’t caused drought in the past, and is not causing it now, we are certain it will cause drought in the future. Science Fiction, anyone?
Wow. Parts of the Midwest could be subj to drought the study says! I mean, that’s never happened before. 😒
Anthony, I got to admit that I’m getting pretty tired of you always banging on about Climate Change. Have you ever stopped to consider for one moment that the warmists may be correct? At any rate some of us have got some real problems to worry about. Following Scotland’s independence referendum is September, I wouldn’t discount a war between the former UK (FUK) and Norway over oil rights:
Cameron Warns Norway over Shetland Land Grab
He heat will shrivel the tropical forests. We are dooomed I tells ya!
Higher evaporation rates from higher humidity? How does that work?
Here in the tropics, we get 80 to 100% humidity most of the year. I don’t find that it helps to dry my clothes on the line.
Holy cracked mud Batman!
It just show you that you can cherry pick what you want to back your claim. The IPCC is a political organisation charged with cherry picking for the desired results.
I find it interesting that once again the DATA shows an opposite trend for the last 30 years–11% more vegetation, more drought-resistant plants. Why is it that the dire projections are based on the inflated feedbacks of the GCM crew, while the DATA continually slaps them in the face.
http://www.livescience.com/37055-greenhouse-gas-desert-plants-growing.html or
http://onlinelibrary.wiley.com/doi/10.1002/grl.50563/abstract (Paywalled)
Of the risk projections in the WGII report, it looks like increased stress on fresh water supplies and frequency/severity of forest fires are the only categories with moderate current risk. Future dire situations rely on the projects from the models. Of course, we make policy decisions based on “conservation” that exacerbate the two current risk categories.
Keep up the good fight.
What dopes. More CO2 increases water efficiency and drought resistance in plants.
Following up on the study linked by Jimbo, the problem with the IPCC conclusions,IMO is the assumption that the biosphere does not adapt to the increased rainfall. Warming and hotter works very well on this planet … see the tropic belts. Plant species flourish that trap the excess water and reduce the amount of water lost through evaporation.
Even if we assumed the physical models were “getting it right” for a sterile planet (lets assume it, these are reasonable outcomes), they are still just modeling a dead Earth. It’s unfortunate that in an impact statement, worried about the impact of climate change on plants, the role of plants in regulating the climate have been ignored.
Rememberng a past description of a very verdant (paradise) very warm Earth, how do these folks explain that?
Well, climate studies as such are never retracted, so this one will live happily ever after alongside others that predict something else. As for evaporative drying, I am sure it might happen … but: there are plants that are actually well adapted to that, e.g. plants that get their water “out of thin air” alone. Now I’m not saying these will be the future staple foods nor that wheat will be genetically reengineered to condense water from humidity. But I doubt that this story will have any more half-live as any other predictions (q.v. the IPCCs careful reconsideration of the extinction horror scenarios).
beng, “More CO2 increases water efficiency and drought resistance in plants.”
Absolutely. Plant stomata become smaller in a higher CO2 environment, which reduces transpiration losses. Plant response to higher CO2 levels is discussed here.
See also this:
[youtube http://www.youtube.com/watch?v=TuwAtfBk6NI?feature=player_detailpage&w=640&h=360%5D
A cooling climate is the real dryer-outer! Evaporation declines and the moisture there is snows out.