Though the precise circumstances and dynamics will vary from place to place, Syria’s experience illustrates the danger of major upheavals if environmental and resource pressures go unresolved. A recent scientific paper warns that due to climate change, some population centers in the Middle East “are likely to experience temperature levels that are intolerable to humans” by the end of this century. Elsewhere, melting glaciers, sea-level rise, highly variable rainfall, and parched farmland could have potentially dire consequences.

Violence captures the headlines, but there are other worrisome impacts, too; population displacements, for example. In 2008-2014, floods, storms, and extreme temperatures displaced a cumulative 158 million people globally — though the annual figures have fluctuated from a low of 13.9 million to a high of 38.3 million. No comparable data exist for slow-onset disasters such as drought.

The number of people displaced due to climate impacts is expected to rise as extreme weather events become more frequent and intense, and as droughts, desertification, sea-level rise, and glacial melt become more prominent. Yet it seems impossible to make any reliable projections. Outcomes will depend on the time, location, intensity, and frequency of disasters; but also on the level of preparedness and resilience of affected communities.