Governors' Biofuels Coalition

Climate change could prove a daunting foe for the U.S. ethanol industry in the next four decades, according to a new study led by researchers from the University of California, Davis, and Houston-based Rice University.

Changing weather patterns will decrease the amount of corn available for ethanol production while increasing its water needs, creating an unsustainable way forward, the researchers found. If the climate changes as currently forecast by the U.N. climate body, the United States will not meet its biofuel goals set out in the 2007 renewable fuel standard, the study predicted.

“We find that changes in climate in certain areas in the U.S. in the coming decades could lead to reductions in crop yields and an increase in irrigation demand,” the study found. “These projections highlight the need to re-evaluate the sustainability of transportation biofuel policy.”

The study released today by the universities was published online late last month in Environmental Science and Technology, a journal of the American Chemical Society. Its authors, who did not receive outside funding for the study, have previously raised questions about the sustainability of ethanol production and the ability of biofuels to reduce greenhouse gas emissions.

“Whereas biofuels offer a means to use more renewable energy while decreasing reliance on imported oil, it is important to recognize trade-offs,” Pedro Alvarez, principal investigator and chairman of Rice University’s Civil and Environmental Engineering Department, said today.

Basing results off a computer model designed by the Agriculture Department, the study found that climate change will decrease the corn yield in 10 major corn-producing states by an average of 7 percent over the next four decades. Irrigation needs during that same time period will increase by 9 percent.

The results varied by region. In Nebraska and Kansas, where corn acreage is already largely irrigated, irrigation demand will increase by 10 percent due to climate change, the study found. In the Corn Belt states of Iowa, Illinois, Indiana and Ohio, where farmers currently rely on the rain to water their crops, irrigation demand could increase up to 25 percent.

In the Corn Belt, increasing irrigation could require the construction of infrastructure that is subject to economic and legal challenges, the study predicted. In states like Nebraska and Kansas, the increase in irrigation could further stress the already overburdened Ogallala Aquifer, which is losing water at a pace greater than it is recharging.

“The increased irrigation water demands to maintain a nonetheless reduced crop production might prove uneconomical for farmers, especially if water pumping is more costly, threatening the ability to meet the mandated biofuel targets domestically without further subsidies,” the study said.

The study also found that climate change will increase the amount of water that is released by corn crops into the atmosphere, leading to less water available to recharge local waterways. Overall, the adverse effects of higher temperatures brought on by climate change will likely outweigh the beneficial effects of increased atmospheric carbon dioxide concentrations on the corn crop, the study found.

While the model used by the researchers has uncertainties — it does not, for example, fully take into account technological advances that can increase the yield of corn — it has been used before in other academic studies. This most recent study assumes an infinitely available amount of inputs like fertilizers and pesticides

The 10 states studied — Iowa, Illinois, Nebraska, Minnesota, Indiana, Ohio, South Dakota, Wisconsin, Missouri and Kansas — currently produce 84 percent of the corn in the nation. About 40 percent of the nation’s corn currently goes toward producing about 13 billion gallons of ethanol, though byproducts are returned to livestock producers for feed. The renewable fuel standard calls for 15 billion gallons of corn ethanol production a year beginning in 2015.

Any biofuel policy changes going forward need to take into account climate change, the researchers said.

“Biofuels crops are vulnerable to droughts … and to long-term climate-induced water stress,” the study said. “Consequently, a sustainable biofuel policy should consider how climate change would alter both water supply and demand and, in turn, how related changes in water availability will impact the production of biofuel crops.”

Researchers from Switzerland, China and Austria contributed.

Previous | Next