WASHINGTON - It's the kind of scenario that climate scientists have long predicted.
According to a new study, climate change helped set off a chain of events leading to the Syrian civil war.
Another study in the same issue of the Proceedings of the National Academy of Sciences found the record-breaking drought crippling the most populous and most productive state in the U.S. bears the same hallmark of climate change.
The two studies point to the possibility of clear and present dangers from a threat often considered to be far in the future.
From 2007 to 2010, Syria was devastated by the worst drought in the country’s recorded history. Crops failed and livestock died, driving an estimated 1.5 million people from their homes.
“These people picked up their families and en masse migrated to the urban areas to try and survive,” said climatologist and lead study author Colin Kelley. “They weren’t thinking about the future. They were thinking about the present.”
The new arrivals came on the heels of as many as 1.5 million refugees who fled Iraq after the U.S. invasion in 2003. The exodus of internally displaced people “was a very large population shock for these urban areas in Syria that you could argue were on the margin of sustainability in their stress for food and water even before this occurred,” Kelley added.
Neglected by the government, these overcrowded and underserved settlements became breeding grounds of discontent that erupted in April of 2011, the study said.
Working at Columbia University, Kelley and colleagues studied temperature and precipitation trends since 1931 and climate models of greenhouse gas impacts. They found that the warming and drying the region has experienced since the mid-20th century fits well with the models of climate change. They calculate that global warming has raised the odds of a devastating drought in the region two- to three-fold over natural variation.
“We’re not saying that global warming or climate change triggered or caused the uprising,” Kelley said. “What we are saying is that it basically exacerbated the drought that occurred, made it more severe -- the most severe in the observed record. And that this set about a chain of events that ultimately led to the uprising.”
“But,” he added, “this was also due to Syria’s acute vulnerability when the drought hit.” He noted that government policies had encouraged farmers to drain groundwater reserves, leaving them exposed when drought hit. And the country’s population had been growing rapidly before the uprising, putting more strain on resources.
Meanwhile, another study suggests climate change has made more likely the kind of crippling drought facing the U.S. state of California.
One in eight Americans lives in California. The state produces 12 percent of the nation’s GDP, and more than 10 percent of its farm income.
A recent study did not find climate change had altered the state’s precipitation patterns. It concluded that the drought is mostly due to natural weather variations.
But precipitation is only half the equation, according to study author Noah Diffenbaugh, climate scientist at Stanford University.
California has wet years and dry years, Diffenbaugh said, but “we do know from looking at the historical record that low precipitation years have been much more likely -- greater than two times more likely -- to produce drought if they co-occur with warm conditions. And what we’ve found in California is that there’s been a very clear long-term warming.”
That has raised the odds that a year will be both warm and dry, which makes drought much more likely.
“That increase in probability doesn’t occur without the human contribution of greenhouse gases to the atmosphere,” he added.
And in both California and Syria, the future looks to be warmer and drier still.
Diffenbaugh said when global climate reaches 2 degrees C above pre-industrial temperatures, which the U.N. has set as the limit of tolerable warming, every year will be warm or exceptionally warm in California. That means that regardless of whether precipitation patterns change, drought will be very likely in those years with little rain.
Climate models also predict that Syria and the surrounding region will get drier in the coming decades.
“From a farmer’s point of view, it doesn’t bode well for the future if what the climate models are predicting is true,” he said.
And, he added, it raises questions about future civil stability if the trends continue.