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

More than half of the earth’s terrestrial surface is routes – open areas of native vegetation, suitable for pasture. These areas have 50% of world cattle and support the means of subsistence of more than 2 billion people. The US continental is around a third of the course.

Overcoming has long been considered a key factor in the degradation of routes – and is the reason for herd size restrictions or breeding taxes which, in certain places, can limit the ability of breeders to earn a living. But a new Cornell study indicates another variable: climate change.

Using four decades of detailed data from Mongolia, where 70% of the land zone is courses, researchers from Cornell SC Johnson College of Business have found that if larger herds can slightly reduce the productivity of year -year -old journeys, weather and climate have a much greater effect.

“When we look at the equivalent of the county scale very carefully throughout the country, over 41 years, we find that the longer term changes in the conditions of course are fully attributable to climate changes,” said Chris Barrett, The Stephen B. and Janice G. Ashley professor of economics and applied management, in the public policy of Cornell SC Johnson.

The Barrett team found that Mongolian courses are more affected by collective behavior in greenhouse gas emission in the world than by local breeders. They urge decision -makers to focus more attention on global mitigation, as well as the international remuneration of climate damage, and less on tax farmers in a nation that contributes little to global greenhouse gas emissions.

Barrett is the main author of “Climate rather than overgrazing explains most of the primary productivity changes in Mongolia”, published in Science.

Barrett co-authors are Tumenkhusel Avirmed, now research data analyst at Stanford University; Avralt-Ode Purevjav, Ph.D., consultant at the World Bank; And Steven Wilcox, Ph.D., assistant professor of economics applied to Utah State University.

Avivumed grew up on the courses of Mongolia and directed this research, with Purevjav, which is also from Mongolia. Avirmed approached Barrett, who did in -depth research on the courses in Africa, and asked if he had already studied Mongolia.

“I said no,” said Barrett, “and he explained that he was interested in doing research, and he is from Mongolia, and he had access to the data.”

The Mongolian government has an annual end -of -year census of all the country’s cattle, then in June investigations and vegetation samples to determine the conditions. Based on this rich mine of data, in 2021, the Government informed a head -to -hood tax on a national scale, aimed at inducing lower flock levels to combat the unfavorable impacts perceived.

The Barrett team used this data with a sophisticated statistical analysis method in two stages, using the flock census data at the “SOUM” level – a SOUM is similar to a county – as well as “DZUD” events (extreme winter storms that cause massive livestock mortality) on the winter cake ranges, to predict the variation in the hem. This analysis covered the whole country over a period of 41 years.

In the second stage of the study, the researchers used the planned size of the June herd to generate causal estimates of the effects of the size and climate of the herd on the productivity of summer routes. To distinguish between climatic variations and short -term variations, depending on the annual sliding comparisons, the team has built multi -year averages of each variable and compared them over periods of 10 and 20 years.

By analyzing the vast thoroughness of data, the group found that the greater herd sizes have a modest negative effect on the productivity of short -term routes, but no significant effect over longer periods. The climate and even variations from one year to the next had a much more important impact.

The difference was striking, said Barrett.

“I was surprised by the magnitude of the climatic effect in relation to the effects of the size of the herd, even in the short term,” he said. “Even weather changes from one year to the next have had about 20 times the effect of the size of the herd.”

Barrett thinks that this research could encourage Mongolia officials to rethink current methods to preserve the productivity of the courses – methods that can carry out financial pressure on the shepherds.

“It always considered me confusing, why people in costume and bonds in capitals seem to think that pastors do not understand very well how to manage these lands,” said Barrett. “And yet, there is this common belief that you should bring them to reduce their flock sizes. It just hurts the breeders.”