Warming climate–not overgrazing–is biggest threat to rangelands, study suggests

Summary

Credit: Pixabay/CC0 Public Domain More than half of Earth's terrestrial surface is rangeland—vast open areas of native vegetation, suitable for grazing. These areas feed 50% of the world's livestock and support the livelihoods of more than 2 billion people. The continental U.S. is about one-third rangeland. Overgrazing has long been seen as a key factor in rangeland degradation—and is the reason for herd-size restrictions or livestock taxes that in some places can limit herders' ability to make a living. But a new Cornell study points to another variable: climate change. Using four decades' worth of detailed data from Mongolia, where 70% of the land area is rangeland, researchers in the Cornell SC Johnson College of Business found that while larger herds can slightly reduce rangeland productivity year to year, weather and climate have a much bigger effect. "When we look really carefully at the equivalent of county scale over the whole country, over 41 years, we find that the longer-run changes in rangeland conditions are entirely attributable to changes in the climate," said Chris Barrett, the Stephen B. and Janice G. Ashley Professor of Applied Economics and Management, in the Cornell SC Johnson College of Business and a professor in the Jeb E. Brooks School of Public Policy. Barrett's team found that Mongolian rangelands are impacted more by collective greenhouse gas-emitting behaviors around the globe than by local herders. They urge policymakers to focus more attention on global mitigation, as well as on international compensation for climate damages, and less on taxing herders in a nation that contributes little to global greenhouse gas emissions. Barrett is the senior author of "Climate Rather than Overgrazing Explains Most Rangeland Primary Productivity Change in Mongolia," published in Science. Barrett's co-authors are Tumenkhusel Avirmed, now a research data analyst at Stanford University; Avralt-Od Purevjav, Ph.D., a consultant at the World Bank; and Steve...