Climate change could boost cotton yields

December 12, 2001

BOULDER--A new study by scientists at the National Center for Atmospheric Research (NCAR) has found that cotton yields are likely to increase in the southeastern United States if carbon dioxide levels continue to rise as projected this century and if farmers adapt their agricultural practices to the resulting climate change. The findings are being presented this week in San Francisco at the annual meeting of the American Geophysical Union (AGU).

The researchers entered various scenarios into their computer models to simulate the effects of elevated carbon dioxide (CO2) in the atmosphere on cotton crop yields. If CO2 emissions increase at their present rate, many scientists believe that the atmospheric concentrations of greenhouse gases are likely to double compared to pre-industrial levels by the year 2060.

Along with climate change, atmospheric CO2 enhances plant growth by stimulating photosynthesis. In one scenario, adaptations to farming practices resulting from a lengthened growing season, elevated CO2- induced climate change, and enhanced plant growth were all factored into model simulations. The results predict that cotton yields would increase by as much as 26-36%.

"Cotton is a very important economic crop for U.S. agriculture," says NCAR's Linda Mearns, a co-author of the study. "This is the first time impacts of climate change on cotton production have been examined at this level of detail on a regional scale." Nevertheless, explains NCAR co-author Ruth Doherty, these cotton model projections are simplistic. For example, the climate models project climate change based on an instantaneous doubling of CO2, when in reality such increases would occur gradually over this century, possibly changing the outcomes. Still, in most of the scenarios there was a trend towards increased cotton yields in the future.

Two climate models were used in the study--a large-scale global climate model that used 300 by 300 kilometer (186 by 186 mile) grids, and a fine-scale regional climate model that used 50 by 50 kilometer (31 by 31 mile) grids. A climate model is a simplified mathematical representation of the earth's climate system, including data on the physical, geophysical, chemical, and biological processes that govern the climate system. Fine-scale models with higher resolution may be more accurate, but in order to gain information about the future regional climate, results from the global model must be used to initialize and control the regional model.

Using these two models, three scenarios were simulated. The first scenario simply looked at the impact that climate change resulting from an instantaneous doubling of CO2 would have on cotton yields in the southeastern United States, including Alabama, Arkansas, northern Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and part of Tennessee. For this scenario the fine-scale model predicted a decrease of 10% in cotton yield over the region, while the large-scale model showed a 4% increase in yields.

When the climate change resulting from CO2 doubling was combined with the potential for enhanced cotton plant growth as a result of greater carbon availability, the fine-scale model showed a 5% increase in yields, while the large-scale model predicted a 16% increase. Finally, when the first two factors of CO2 doubling and enhanced growth were combined with farming adaptations, such as planting crops earlier to take advantage of a longer growing season, the fine-scale model predicted a 26% increase, and the large-scale model predicted a 36% increase.

The research is part of a larger project that examines the impact of different spatial scales of climate change scenarios on yields of corn, wheat, sorghum, soybeans, and cotton in the southeastern United States. The findings will be published next year in a special issue of the journal Climate Change. NASA and the U.S. Environmental Protection Agency funded the study. NCAR's primary sponsor is the National Science Foundation.
UCAR and NCAR news:

To subscribe via e-mail send name, title, affiliation, postal address, fax, and phone number to

To unsubscribe, please send a message to with the subject line blank and the following instruction in the body of the message:

unsubscribe press-release [your subscribed e-mail address]

Krishna Ramanujan, NASA Goddard
301-286-3026 or
AGU press room: 415-905-1007

National Center for Atmospheric Research/University Corporation for Atmospheric Research

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to