A new study conducted at the Potsdam Institute for Climate Impact Research (PIK) shows that grassland-based grazing systems – currently covering a third of the Earth's surface and representing the world's largest production system – will see a severe contraction as global temperatures rise. Depending on the scenario analysed, 36-50 percent of the land with suitable climatic conditions for grazing today will experience a loss of viability by 2100, affecting more than 100 million pastoralists and up to 1.6 billion grazing animals.
The study, published in the scientific journal PNAS today, identifies a 'safe climatic space' for cattle, sheep and goat grazing. To date, these agricultural systems have thrived within certain ranges of temperature (from −3 to 29°C), rainfall (between 50 and 2627 millimetres per year), humidity (from 39 to 67 percent) and wind speeds (between 1 and 6 metres per second).
"Climate change will shift and significantly contract these spaces globally, leaving fewer spaces for animals to graze. Importantly much of these changes will be felt in countries that already experience hunger, economic and political instability, and higher levels of gender inequity," commented lead author Chaohui Li, PIK researcher at the time the study was conducted and now with the Barcelona Supercomputing Center.
"Grassland-based grazing is highly dependent on the environment, including things like temperature, humidity, and water availability. What we see is that climate change is going to reduce the spaces in which grazing can thrive, fundamentally challenging farming practices that have existed for centuries," commented Maximilian Kotz, another of the study's coauthors and researcher at the Barcelona Supercomputing Center and PIK.
Africa a hotspot for impacts on grazing
The authors highlight that Africa will be particularly vulnerable. Grasslands in Africa could reduce by 16 percent in a low emissions scenario, or up to 65 percent in a future in which fossil fuels continue to expand, as temperatures on the continent already sit at the upper end of the safe climatic space identified as suitable for grazing.
As temperatures rise, the climate niches currently supporting critical grazing regions in the Ethiopian highlands, the East African Rift Valley, the Kalahari Basin, and the Congo Basin will shift southward. Because the African landmass terminates at the Southern Ocean, these suitable temperature belts would eventually extend beyond the continent's edge, resulting in a loss of viable grazing land.
"This shift away from what we're identifying as the safe climatic space really challenges the efficacy of adaptation strategies that have been used in places such as Africa in times of hardship, such as switching species or migrating herds. The changes are just too big for that," said Prajal Pradhan, assistant professor of the University of Groningen, PIK researcher and a coauthor of the study.
"Reducing emissions by rapidly moving away from fossil fuels is the best strategy we have to minimise these potentially existential damages for livestock farming," Li concluded.
