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Rainfall variability increases in global grazing lands

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February 20, 2018

A new study published in Nature Climate Change has found year-to-year variability in rainfall has increased in the world’s grazing lands over the last century.

Pastures and rangelands underpin global meat and milk production and are a critical resource for millions of people dependent on livestock for food security.

An estimated 22% of the Planet’s ice-free land is used for livestock grazing. “Grazing lands are naturally known for their highly variable rainfall; about 25% more year-to-year variability than other lands,” co-author CSIRO Agriculture and Food Chief Research Scientist Mario Herrero explained.

“This study is showing us that grazing is potentially highly vulnerable to climate change; right across the world, from Australia to Central Asia, sub-Saharan Africa and the Americas” said Mario Herrero.

The study looked at historical climate data in the major grazing regions of the world from 1901 to 2014.

“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 the University of Minnesota.

The study found that 49% of global grazing lands experienced significant increases in year-to-year rainfall variability and 31% experienced significant decreases.

“What is particularly worrying is that the areas especially affected by the increasing variability trends are areas where livestock grazing is important for food access and economies” said co-author Cecile Godde, PhD candidate with CSIRO Agriculture and Food.

There are around 600 million rural poor who rely on livestock for their livelihoods.

“If a region such as the Sahel in Africa experiences a lot of variation in rainfall, pastoralists will not be able to maintain their herds and this could exacerbate poverty and malnutrition” said Cecile Godde.

In Australia, the researchers say, we have a long history of climate variability, which has meant our graziers have found innovative ways to adapt to these conditions.

In recent times, graziers have tended to alter the number of livestock they keep in response to how much feed is available. They also hold off on restocking after droughts to give pastures enough time to recover.

“Strategies such as these will become ever more vital as our climate becomes increasingly variable,” said Mario Herrero.

For a visual summary of the work see Food Matters.