BOGOTA - Billions of people live on farmland that is deteriorating and producing less food, and this situation could force hundreds of millions of people to migrate over the next three decades, a major report said on Monday.
The study, which is backed by the United Nations, said climate change and worsening land quality could see crop yields halve in some regions by 2050, and warned that larger tracts of degraded land meant conflict over resources was more likely.
?Decreasing land productivity also makes societies more vulnerable to social instability ? particularly in dryland areas, where years with extremely low rainfall have been associated with an increase of up to 45 percent in violent conflict,? said Robert Scholes, the report?s co-author.
The report was written by more than 100 experts from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), a global scientific group.
The body said that as degraded land becomes less productive - through deforestation, overgrazing, flash floods or drought - people, many of them poor farmers, are forced to migrate to cities or abroad.
And, it warned, when arid, semi-dry or dryland areas degrade further, deserts spread - which means lower crop yields.
?In just over three decades from now, an estimated 4 billion people will live in drylands,? Scholes said.
?By then it is likely that land degradation, together with the closely related problems of climate change, will have forced 50-700 million people to migrate,? he said.
Increasing demand for food has led to the rapid expansion and unsustainable management of crop and grazing lands, which are key factors in worsening land quality.
It said the problem had reached ?critical levels? in many areas, with wetlands particularly badly affected.
Land degradation drives climate change, with deforestation - which contributes 10 percent of human-caused greenhouse gas emissions - and soil erosion worsening the problem, it said.
?Land degradation, biodiversity loss and climate change are three different faces of the same central challenge: the increasingly dangerous impact of our choices on the health of our natural environment,? said Robert Watson, an atmospheric scientist.
The report said land could be restored by planting trees, using salt-tolerant crops, and re-flooding drained wetlands.
More than 550 IPBES experts from more than 100 nations are meeting in Colombia where a set of peer-reviewed regional reports about the state of nature in the Americas, Asia and the Pacific, Africa, Europe and Central Asia have been launched.