The two major circulation patterns that influence when droughts occur in the Mediterranean are the North Atlantic Oscillation and the East Atlantic Pattern. These airflow patterns describe how winds and weather tend to behave depending on ocean conditions. They have periodic phases that tend to steer rainstorms away from the Mediterranean and bring in dryer, warmer air. The resulting lack of rain and higher temperatures, which increase evaporation from soils, lead to droughts.
“The Mediterranean is one of the areas that is unanimously projected [in climate models] as going to dry in the future [due to man-made climate change],” said Yochanan Kushnir, a climate scientist at Lamont Doherty Earth Observatory, who was not involved in the research. “This paper shows that the behavior during this recent drought period is different than what we see in the rest of the record,” he said, which means that the Levant region may already be feeling the affects of human-induced warming of the planet.
The 900-year record of drought variability across the Mediterranean is an important contribution that will be used to refine computer models that are used to project drought risk for the coming century, Kushnir said.