The recent drought that began in 1998 in the eastern Mediterranean Levant region -- comprising Cyprus, Israel, Jordan, Lebanon, Palestine, Syria, and Turkey -- is about 10 to 20 percent drier than the worst drought of the past nine centuries, a NASA study has found.Scientists reconstructed the Mediterranean's drought history by studying tree rings as part of an effort to understand the region's climate and what shifts water to or from the area.Thin rings indicate dry years while thick rings show years when water was plentiful.The research, accepted for publication in the Journal of Geophysical Research-Atmospheres, is part of NASA's ongoing work to improve the computer models that simulate climate now and in the future."The magnitude and significance of human climate change requires us to really understand the full range of natural climate variability," said study lead author Ben Cook, climate scientist at NASA's Goddard Institute for Space Studies in New York."If we look at recent events and we start to see anomalies that are outside this range of natural variability, then we can say with some confidence that it looks like this particular event or this series of events had some kind of human caused climate change contribution," he said.
Cook and his colleagues used the tree-ring record called the Old World Drought Atlas to better understand how frequently and how severe Mediterranean droughts have been in the past. Rings of trees both living and dead were sampled all over the region, from northern Africa, Greece, Lebanon, Jordan, Syria and Turkey. Combined with existing tree-ring records from Spain, southern France, and Italy, these data were used to reconstruct patterns of drought geographically and through time over the past millennium. Between the years 1100 and 2012, the team found droughts in the tree-ring record that corresponded to those described in historical documents written at the time. According to Cook, the range of how extreme wet or dry periods were is quite broad, but the recent drought in the Levant region, from 1998 to 2012, stands out as about 50 percent drier than the driest period in the past 500 years, and 10 to 20 percent drier than the worst drought of the past 900 years.