Public Release: 12-Jul-2017
By 2050, the Southwest will produce significantly less cotton and forage, researchers report
Massachusetts Institute of Technology
A new study by MIT climate scientists, economists, and agriculture experts finds that certain hotspots in the country will experience severe reductions in crop yields by 2050, due to climate change’s impact on irrigation.
The most adversely affected region, according to the researchers, will be the Southwest. Already a water-stressed part of the country, this region is projected to experience reduced precipitation by midcentury. Less rainfall to the area will mean reduced runoff into water basins that feed irrigated fields.
Production of cotton, the primary irrigated crop in the Southwest and in southern Arizona in particular, will drop to less than 10 percent of the crop yield under optimal irrigation conditions, the study projects. Similarly, maize grown in Utah, now only yielding 40 percent of the optimal expected yield, will decrease to 10 percent with further climate-driven water deficits.
In the Northwest, water shortages to the Great Basin region will lead to large reductions in irrigated forage, such as hay, grasses, and other crops grown to feed livestock. In contrast, the researchers predict a decrease in water stress for irrigation in the southern Plains, which will lead to greater yields of irrigated sorghum and soybean.
If efforts are made to reduce greenhouse gases and mitigate climate change, the researchers find that water scarcity and its associated reductions in cotton and forage can be avoided.
“In the Southwest, water availability for irrigation is already a concern,” says first author Elodie Blanc, a research scientist at MIT’s Joint Program on the Science and Policy of Global Change. “If we mitigate, this could prevent added stress associated with climate change and a severe decrease in runoff in the western United States. But it will be even worse in the future if we don’t do anything at all.”
Blanc’s study appears in the journal Earth’s Future, and her co-authors are Erwan Monier, a principal research scientist at MIT; Justin Caron, an assistant professor at HEC Montreal; and Charles Fant, a former MIT postdoc.
While many researchers have investigated the effects of climate change on crop yields, Blanc’s study is one of the first to consider how a changing climate may shape the availability and distribution of water basins on which irrigated crops depend.
“Most modeling studies that look at the impact of climate change on crop yield and the fate of agriculture don’t take into account whether the water available for irrigation will change,” Monier says.
In predicting how climate will affect irrigated crop yields in the future, the researchers also consider factors such as population and economic growth, as well as competing demands for water from various socioeconomic sectors, which are themselves projected to change as the climate warms.
“We try to be as representative of reality as possible,” Blanc says.
To do this, the researchers used a model of 99 major river basins in the country, which they combined with the MIT Integrated Global System Model-Community Atmosphere Model — a set of models that simulates the evolution of economic, demographic, trade, and technological processes. The models also include the greenhouse gas emissions and other pollutants that result from these processes, and they incorporate all of that information within a global climate model that simulates the physical and chemical processes in the atmosphere, as well as in freshwater and ocean systems.
“We’re looking at a more integrated world, and how all these interactions will drive changes in irrigation,” Monier says.
“Severely accentuated” shortages
The researchers focused their global simulations on the U. S. and modeled the country’s evolving economic activities in different geographic regions to determine the water requirements for five main sectors: thermoelectric cooling; public supply, such as for drinking water and other public utilities; industrial demand; mining; and irrigation.
They then used a crop model to simulate daily water requirements for various crops, driven by the researchers’ modeled projections of precipitation and temperature, and compared these requirements with the amount of water predicted to be available for irrigation in a particular basin through the year 2050.
“The biggest finding is that it really makes a difference in specific regions, whether you take into account how irrigation availability will change in the future and how that will impact yields,” Monier says.
By 2050, the team projects that, under a business-as-usual scenario, in which no action is taken to reduce greenhouse gases, a number of water basins in the U.S. will start experiencing water shortages. Several basins, particularly in the Southwest, will see existing water shortages “severely accentuated,” according to the study.
The researchers note that the basins that will be the most affected generally do not supply the largest areas of irrigated cropland. For example, though climate change will significantly reduce cotton production in the Southwest, the bulk of the country’s cotton production does not occur in this region.
“It may not matter too much for the total crop production of the U.S., but if you’re a farmer in that particular region that’s going to be impacted, that matters to you,” Monier says. “What we want to do is provide useful information that either farmers or land investors can use to look into the future and make decisions on where is the right region to expand irrigated agriculture, and where is it more risky. We also want to make clear that climate mitigation is better for U.S. irrigated agriculture than not doing anything.”
A climate-changing landscape
Under the same business-as-usual scenario, the researchers projected higher yields for irrigated crops such as wheat, soybean, and sorghum. The increased production in these crops is driven by higher precipitation predicted to occur in the central U.S., combined with higher concentrations of carbon dioxide, which reduces a plant’s water requirements.
The researchers predict that crop yields for wheat, soybean, and sorghum should increase even more if mitigation measures are put in place. In addition to a business-as-usual scenario, the team ran its simulations under two mitigation scenarios, previously proposed by the U.S. Environmental Protection Agency, in which efforts are made to mitigate global warming to 2 and 3 degrees Celsius, relative to pre-industrial times.
They found that both mitigation scenarios should increase yields for all crops compared to the business-as-usual scenario, including cotton and forage, and that the more ambitious scenario has the potential to reduce the number of water-stressed basins.
Going forward, the researchers plan to factor into their simulations various ways in which climate change drives adaptation, and how such adaptations in turn shape crop patterns and the agricultural landscape.
“In the real world, if you’re a farmer and year after year you’re losing yield, you might decide, ‘I’m done farming,’ or switch to another crop that doesn’t require as much water, or maybe you move somewhere else,” Monier says. “That’s the next step: How would the agricultural sector adapt?”
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This research was supported, in part, by the U.S. Environmental Protection Agency and the U.S. Department of Energy.
Additional background
Paper: Is Current Irrigation Sustainable in the United States? An Integrated Assessment of Climate Change Impact on Water Resources and Irrigated Crop Yields
http://onlinelibrary.wiley.com/doi/10.1002/2016EF000473/full
ARCHIVE: Gauging the impact of climate change on U.S. agriculture
http://news.mit.edu/2016/gauging-climate-change-impact-on-agriculture-0707
ARCHIVE: Watering the world
http://news.mit.edu/2017/design-cuts-costs-energy-drip-irrigation-0420
ARCHIVE: Climate change to worsen drought, diminish corn yields in Africa
http://news.mit.edu/2017/climate-change-drought-corn-yields-africa-0316
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The real issues of climate and climate change on agriculture werediscussed in the following three books:
Agroclimatic/Agrometeorological Techniques: As applicable to dry-land agriculture in developing countries, 1993
Andhra Pradesh Agriculture: Scenario of the last four decades, 2000
“Green” Green Revolution: Agriculture in the perspective of Climate Change”, 2011
In Agriculture, the principal factor that affect the production is rainfall and storage facilities including sols. If the rainfall presents a cyclic variation, the temperature follow the rhythm. This is defined by the crop-soil-water balance. So far there are no indications that world rainfall is changing with GW. This is also stated by IPCC in its AR5.
Dr. S. Jeevananda Reddy
The Duke had this figured out long ago!
Damn I blew it again! Check the clip from about 9:00 to 11:30.
Where the Duke got it right is from 8:14 to 8:24, “…political appointees running it according what they learned in some college where they think cows are something you milk and Indians are something you find in front of a cigar store”.
Never trust anybody that hasn’t “been there”!
Warning.
Very high UV radiation at the surface.
http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/uvi_map_big.gif
Ozone layer is decreasing.
http://exp-studies.tor.ec.gc.ca/ozone/images/graphs/gl_dev/current.gif
In red UV area why there are patches of 4 and 2?
Dr. S. Jeevananda Reddy
You have to take into account cloudy.
http://www.ssd.noaa.gov/goes/comp/ceus/flash-wv.html
There is a known reduction in the levels of aquifers such as the Ogallala. I don’t deny this.
To connect this to climate change is a fool’s errand. The record doesn’t show a reduction in rainfall. The only thing that has changed is the number of wells that are pumping from aquifers. Climate has nothing to do with it. Trying to grow crops on arid land has everything to do with it
Having grown up in the central US I have memories of fields of nothing but winter wheat or milo all across central and western Kansas. Last summer I was traveling and was shocked by the many fields of corn in western Kansas. Corn is a water intensive crop and the only way to it grow in the arid plains of western Kansas is to pump huge amounts of water from aquifers.
Doesn’t take a scientist to understand this is the cause of the aquifer reduction. The fact farmers are raising dent corn in these areas speaks more to the price of corn than climate change.
Areas overlaying the Ogallala have had epic flooding in recent years, and yet no provisions are made for using these waters to recharge the aquifer by means of engineered recharge basins.
Could it be the ethanol-to-fuel mandates?
Weird research focusing on the uncertain future.
Over-exploitation of the Ogallala Aquifer is a real threat and almost totally ignored, though we can be more certain of its impact on long-term prospects for agricultural communities in several states.
Plus the energy used to pump Ogallala water produces lots of GHG emissions that, according to conventional wisdom, are a threat to agricultural communities.
Bizarre.
Plus, I forgot to mention that the water in the Ogallala aquifer is fossil water dated to the last glacial maximum, about 20,000 years or so before the present.
Nothing at all to do with present climate.
Bizarre science. Science?
I agree Brian and Fred – I wrote this in 2012:
http://wattsupwiththat.com/2012/09/06/nyt-blames-food-crisis-on-climate-change-hides-plea-to-reduce-government-mandated-burning-of-food-for-fuel/#comment-1072955
One further point that I first looked into a decade ago:
[Excerpt]
Since then I’ve learned that the vital Ogallala aquifer is dropping at an alarming rate in some locations, due to excess withdrawal of water for irrigation – much of it for corn ethanol.
If the environmental movement truly had the interests of America and the world at heart, they would abandon their fascination with wasteful, inefficient corn ethanol, wind power and solar power, and focus on real environmental problems like vital groundwater conservation.
However, if one analyses their actions, it is clear that the “greens” are not interested in the environment or the wellbeing of humankind. Rather, the environment is merely a convenient smokescreen for their far-left political objectives.
An idea for the next Hollywood Sci-Fi movie:
Carbon-based lifeforms on a distant planet, 70% covered with water and with far less carbon than elsewhere in the universe, start prognosticating water shortages in over 30 years unless carbon is reduced. Nah, too incredible. Oh, wait…
How about towing Larsen C iceberg to US Southwest coast?
That idea has been floated before. Very expensive just getting it there, and then you have to harvest the water, filter it, and get it to where it’s needed.
Has money ever been an issue in the planet CACA?
July 17 strong jump density and speed of the solar wind can cause severe earthquake.
http://www.swpc.noaa.gov/communities/space-weather-enthusiasts
IRRIGATION is depleting the water basins used for irrigation.
Thank you, that will be five cents please.
” a water-stressed part of the country”
Liberal wording for a desert. Just like “high challenged” for short people and “weight challenged” for fat people.
Funny how the “scientists” always have to invent or extrapolate some kind of “effect” far in the future to try keeping the climate-weirding money-train rolling. Often the scenarios are absolutely absurd — like your wing-wang causing global warming. They can’t EVER come up with something that’s actually happening.
Hi Forrest.
Every one of the warmists’ scary predictions has failed to materialize – they have perfectly negative credibility.
Did the account for the well-proven fact that with higher CO2 levels, plants need less water and are MORE tolerant of drought? And did the consider that over the next 28 years that new cultivars of those crops will be developed for the new conditions?
No.
Climate alarmism is a fact free field of study.
Riiiiight…… Build a model to support the conclusions you slready decided in advance and somehow that somehow is valid? Seems ten years ago they were using models that predicted our food crop yields would be collapsing within the decade. Until you have a model that is proven reliable you sure in the heck shouldn’t be using it to set policy! This climate agenda is downright nauseating.
Climate change to lower science standards to levels of political campaigns.
Maybe if we were to stop burning 40% of our US corn crop as motor fuel, it would free up some land in less arid areas for other crops. Maize in Utah? Seriously?
So, more water in the system is going to deplete water.
Got it.