Nearly half of the world's pastureland is experiencing notable changes in precipitation, driving up the risk to grazing and herding communities around the world, according to data collected by a team of U.S., Australian and Brazilian scholars.

The research, led by the University of Minnesota's Institute on the Environment and published in the journal Nature Climate Change, relied on climate data from 1901 to 2014 to create global maps of precipitation variability trends across the world's primary grazing regions.

While some grazing regions showed decreases in water variability, the dominant trend is increased fluctuations in precipitation, the research shows.

Globally, grazing lands experienced about a 25 percent increase in year-to-year precipitation variation compared with the average global land surface area, with 49 percent of pasture area seeing more variability while 31 percent saw less variability.

Such findings could have substantial implications for the roughly 800 million people around the world who depend on grazing livestock for their livelihoods and for food security.

"In a good season, grasses and other plants flourish, supporting robust herds," the researchers said. "In a bad season, the system suffers—as do the people who rely on it. The difference between a good and bad year? One significant and increasingly volatile factor is precipitation."

Lindsey Sloat, the study's lead author and a postdoctoral research associate with the Global Landscapes Initiative at the University of Minnesota, said the research effort "allows us to identify grazing lands that have undergone large changes—and to learn from those places where people have managed to adapt well despite increased variability."

Paul West, co-director of the Minnesota research group, said the findings are especially important because many of the world's grazing lands are considered marginal, meaning they are unsuitable for growing crops because they're either too dry or have poor soils.

"Even small changes in rainfall put them at more risk," West said. Moreover, greater precipitation variability poses the most consequence to marginal lands. Those lands tend to be held by small farmers and pastoralists who depend on livestock for income and sustenance.

Study co-author Mario Herrero of Australia's Commonwealth Scientific and Industrial Research Organisation said the research reinforces the idea that "grazing is potentially highly vulnerable to climate change, right across the world, from Australia to Central Asia, sub-Saharan Africa and the Americas."

Globally, some of the greatest increases in variability have been seen in Central Asia, northern Australia, the Sahel region of Africa and portions of South America. In the United States, precipitation variability has increased in the Intermountain West and Baja California, while variability has decreased in the Great Plains.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at