 Most climate models tend to agree on the Earth's future when it comes to temperature. At our current pace of greenhouse gas emissions, it's going to get hotter everywhere. That makes intuitive sense. What's less obvious is what's going to happen to precipitation. Models are generally in much weaker agreement about precipitation changes, but they seem to converge in predicting that certain areas are definitely going to get wetter and others drier. Among these, the Mediterranean stands out. Locally, the region may lose up to 40% of its winter precipitation. For the millions who depend on these seasonal rains, it's a serious threat to their way of life. But researchers have yet to explain why numerous climate models settle on the same fate. Now, researchers from MIT have discovered two mechanisms that could converge to create this dire scenario, strengthening winds in the upper troposphere at an altitude of about 10 km and a diminishing temperature difference between land and sea. Both mechanisms have the same general effect of creating higher pressure over the Mediterranean. The distribution of winds in the upper troposphere is related to surface pressure patterns. An overall strengthening of these winds around the latitude of the Mediterranean will cause an eastward expansion of the high pressure zone currently above the North Atlantic. During winter, the Mediterranean sea is, on average, warmer than the surrounding land thanks to water's high capacity to absorb heat. But relatively enhanced warming over land due to climate change means that the wintry temperature differential will likely shrink over the next century. This is equivalent to a relative cooling over the sea which in turn will translate into higher pressure over the Mediterranean. When tested on various climate models, adjustments accounting for each of these mechanisms are intended to reproduce well-known future climate trends. About 40% of the projected increase in Mediterranean sea-level pressure can be attributed to wind-flow anomalies in the upper troposphere with another 40% linked to the half-degree dip in the sea-land temperature gradient. Much work remains to understand the variations in pressure and precipitation patterns across the climate models used by the team. But altogether, the circulation and temperature mechanisms they've teased out to explain the dry winters predicted for the Mediterranean under unmitigated change. Understanding these forces could provide some measure of preparedness for those who call this region home.