Submitted by theadminx on Tue, 11/27/2012 - 22:22
November 27, 2012 by Melissa Gaskill, Scientific American
A cool October broke a 16-month streak of above average temperatures across the Lower 48, but temperatures are projected to remain above normal across most of the western half of the country in the coming months.
In addition, the latest climate change projections put future temperature gains on the high side of various models.
As of November 6, 59.5 percent of the contiguous U.S. was experiencing persistent drought conditions that are most severe in the Great Plains — North and South Dakota, Nebraska, Kansas, Oklahoma, Texas, Montana, Wyoming and Colorado — where drought is expected to persist or intensify in the foreseeable future.
On October 17–18 those drought conditions combined with high winds to create a large dust storm across Colorado, Nebraska, Kansas, Oklahoma and Wyoming, closing major highways.
To Katharine Hayhoe, professor and director of the Climate Science Center at Texas Tech University in Lubbock, this heralds big changes for agriculture on the Great Plains. "In a nutshell," Hayhoe says, "we're seeing major shifts in places and times we can plant, the types of crops we can grow and the pests and diseases we're dealing with.
"If you talk to seed companies, the U.S. Department of Agriculture (USDA) and even farmers, they tell you we can modify our way out of this, that we can overcome all these problems with technology. There's no question we can adapt to some of the change, but whether we can adapt to all of it is a very open question."
In the 1930s Dust Bowl a land speculator– and government-encouraged plowing frenzy removed windbreaks and grasslands that stabilized soil. The dry, windy weather that followed created one of the worst man-made ecological disasters ever. Powerful windsscoured bare soil from the ground and carried it long distances. Farms failed across Colorado, Kansas, Oklahoma and Texas.
This October's dust storm, which followed preparation of fields for fall planting, could be the first act of an encore performance. "If the drought holds on for two or three more years, as droughts have in the past, we will have Dust Bowl conditions in the farm ng belt," says Craig Cox, an agriculture and natural resources expert with the Environmental Working Group, a nonprofit using public information to protect public health and the environment.
"It could be in a sense an invisible Dust Bowl—not like the big storms before, but withered crops, dry streams and other disasters that accompanied the Dust Bowl. Wind erosion is tremendously damaging and hard to control. A lot of practices that control wind erosion require growing things, and if those weren't in place when the drought hit, it's almost impossible to put them in place now."
Since the 1940s agriculture on the semiarid southern Great Plains — Colorado, Kansas, Oklahoma and Texas — has relied on irrigation. On the high plains of Texas, tens of thousands of wells pumping from the 10-million-year-old Ogallala Aquifer have depleted it by 50 percent. Given variation in its depth and the difficulty of pumping at low water levels, most of the remaining reservoir will likely be useless for irrigation within about 30 years.
At the same time, climate change has brought less rain as well as hotter temperatures that increase evaporation — forcing farmers to use even more water for irrigation. "We have agriculture systems in semiarid areas," Hayhoe says. "We built these vulnerabilities into the system and climate change is the final straw that may break the camel's back."
Agriculture on the southern plains isn't necessarily doomed, though, Hayhoe stresses. "There are techniques being developed already, such as dry-land farming, rotating crops and using waste as biofuel that will keep the economy going." Actions also can be taken at the local level to reduce the vulnerability of agriculture, she says, including using energy more efficiently and developing sounder management and development policies.
Other adaptations include switching to more heat-tolerant breeds of livestock and even away from cattle altogether, says Wayne Polley, research ecologist at the USDA's Grassland, Soil and Water Research Laboratory. "Major changes in agricultural land use will mean changes in our eating habits and our family budgets as well."
"There are absolutely things farmers could do to deal with climate change," Cox says. "This is not a technical problem. There is a whole suite of practices that would make farming systems more resilient and able to stand up to climate change. Yet instead of making farming more resilient to the challenges, current government agricultural policy actually takes us in the opposite direction."
Ending mandates for corn ethanol and once again tying crop insurance to land conservation would help reduce erosion and drainage of wetlands on farmland, he says, reducing the risk of returning Dust Bowl conditions.
The good news, Hayhoe adds, is that whatever happens, the land will still be here. "In the southern Great Plains we may have a major shift to dry-land crops. We may have to shift when we plant. But we have the option of trying different things — as opposed to, say, Bangladesh, where cropland is being lost to sea-level rise.
"We can save ourselves by wise planning," she says. "But a lot of change has been hampered because people don't want to do anything that has a 'climate change' label on it, and also because industrial, large-scale systems are resistant to changes because changes are expensive. But that's true only in the short term. Not doing anything will be way more expensive in the long term. Business as usual is not going to be a viable option 30 years from now, or even sooner."
Fifty miles south of Hayhoe's Texas Tech office, agricultural fields line an arrow-straight highway. On a dry, windy day, in circular fields created by wheeled irrigation contraptions that spin from a well in the center, water sprays onto new autumn crops.
Enormous bales of recently harvested cotton stacked up at nearby gins render bits of the snowy fluff to the wind, which catch the grass along the road's edge to gather into miniature drifts. As temperatures rise and the aquifer levels fall, these iconic images of high plains agriculture may be blown away with the dust.