There's been growing chatter over the years suggesting that global climate change can spark wars, particularly in developing countries where drought conditions could lead to conflict over water rights. Just last week, the New Yorker's Michael Specter wrote that "the result of continued inaction is clear ... water wars are on the horizon."
According to some, those wars are already here. In a paper out today in Proceedings of the National Academy of Science, climate researcher and PACE fellow Colin Kelley and colleagues at Columbia University argue that the ongoing Syrian civil war was the indirect result of the planet's rising temperature.
The researchers became interested in the subject after reading editorials about the Arab Spring, specifically "about how environmental stresses, different in every Arab Spring country, had been overlooked in their contributions to the uprisings," Kelley writes in an email. "We knew there had been a severe multiyear drought in the years just prior to the Syrian uprising," he continues, which likely precipitated the Syrian conflict. That drought stretched from 2007 to 2010 and decimated the country's wheat production, driving farmers into urban areas and ultimately into conflict with their new neighbors.
Comparing scenarios with and without 20th-century human activities, the team reached much the same conclusions as they had by looking directly at their data: If climate change hadn't caused the civil war, it had certainly made it more likely.
But whether the drought has its origins in natural variation or in human-sourced climate change was less obvious, Kelley says. To sort that out, the team collected data on precipitation from around the Fertile Crescent covering the years 1931 to 2008. They then compared that data with long-term trends in global atmospheric carbon dioxide, allowing them to infer what the natural variability in rainfall would have been had CO2 levels stayed constant over the last century. Finally, they compared the hypothetical natural variability with the actual, observed variability in rainfall.
Their conclusion was stark: Severe, three-year-long droughts are two to three times more likely than they would be without human contributions to CO2 in the atmosphere. That was backed up by climate simulations from the CMIP5, a set of standard computer models that allow researchers to study how the climate evolves under different scenarios about human contributions to climate change. Comparing scenarios with and without 20th-century human activities, the team reached much the same conclusions as they had by looking directly at their data: If climate change hadn't caused the civil war, it had certainly made it more likely.
"These results, taken together, along with previous studies strongly argued that the trends were in fact human induced," Kelley writes. Though others have linked historical conflicts to major climate events, "we feel this is the first study in a major peer-reviewed journal that links climate change to modern civil unrest," he adds.