February 20, 2018

Livestock under threat from dwindling grazing lands due to changing climate

Precipitation variability over the past century has increased significantly on 49% of the world's grazing lands, affecting vegetation and constraining their ability to support livestock, according to a new study published in Nature Climate Change journal.

The study used climate data from 1901 to 2014 to create global maps of precipitation variability trends.

While some grazing lands showed decreases in rainfall variability, the overall trend is an increase in fluctuation, both within and between years, says the study, conducted by a team from the University of Minnesota Institute on the Environment (IonE).

The authors of the study said some 800 million people around the world depend on livestock that graze on natural vegetation for their livelihoods and food security.

"Visualizing precipitation variability trends 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", said lead author Lindsey Sloat, a postdoctoral research associate with IonE's Global Landscapes Initiative (GLI).

The study said grazing lands have reached a point that they are already typically marginal: unsuitable for crops, either too dry or with poor soils.

"Even small changes in rainfall put them at more risk", said GLI co-director Paul West, adding that some grazing lands are even more inhospitable than others. These more vulnerable lands, he said, tend to be home to the smallholder farmers and pastoralists who most depend on livestock for food.

The researchers found that regions with high year-to-year precipitation variability support lower livestock densities than less variable regions. Rick Alberto