Continued elevated carbon dioxide concentrations in the atmosphere may reduce forage quality among the world's grasslands and lead to reduced weight gain among animals, according to Agricultural Research Service scientists and cooperators. Their five-year study was published in the journal Ecological Applications.

Plant physiologist Jack A. Morgan led the study with ARS colleagues and cooperators at Colorado State University. Morgan heads the ARS Rangeland

Atmospheric concentrations of carbon dioxide have been rising steadily during the last 150 years. The compound is considered a major greenhouse gas because of its ability to trap heat near the Earth's surface. Fossil-fuel burning, forest clearing and industrial manufacturing account for most of the increased carbon dioxide emissions.

An intergovernmental panel on climate change has estimated that atmospheric CO2 concentrations will double over today's levels by the end of the 21st century.

The scientists found that forage quality declined in all three dominant grasses under the elevated carbon dioxide conditions, due largely to lower tissue nitrogen content.