American Geophysical Union: A new study finds that the recent drought that began in 1998 in the eastern Mediterranean Levant region, which comprises Cyprus, Israel, Jordan, Lebanon, Palestine, Syria, and Turkey, is likely the worst drought of the past nine centuries.

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.

In addition to identifying the driest years, the science team discovered patterns in the geographic distribution of droughts that provides a “fingerprint” for identifying the underlying causes. Together, these data show the range of natural variation in Mediterranean drought occurrence, which will allow scientists to differentiate droughts made worse by human-induced global warming. The research 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 Ben Cook, lead author and climate scientist at NASA’s Goddard Institute for Space Studies and the Lamont Doherty Earth Observatory at Columbia University in New York City. [Continue reading…]