A recent NASA research shows that a drought which has been affecting eastern Mediterranean Levant region, including Turkey, Cyprus, Israel, Jordan, Lebanon, Palestine and Syria, since 1998 is the most severe drought in last 900 years.
Scientists studied tree rings to understand climate change and water shifting in the region all over the Mediterranean area. Thin rings confirm that quantity of water was lower and these years are considered dry years, and vice versa that thick rings attest water was plentiful in those years.
Research data on the rings was collected from trees across the region including northern Africa, Turkey, Greece, Lebanon, Jordan and Syria. To analyse precipitation level between 1100 and 2012, the team compared the results obtained from tree-ring record and historical documents written and thought the correlation between two ranges of the results.
Even though the scale of wet or dry periods were wide, recent drought in the Levant region, from 1998 to 2012, is up to 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, according to Cook.
The study was published in the journal Geophysical Research Letters.
After identifying the driest years, the researchers noticed geographical patterns which reflect geographic distribution of droughts to plainly grasp fundamental reasons in the long periods. Using the collected data, they try to differentiate droughts caused by natural change and human-involved damage.
"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.
Main criterion to distinguish drought whether it occurred naturally or due to human-caused damage is to compare it with the scale of natural change.
Drought occurs when a region receives extremely little rain for an unusual period, and it deepens in case of increased temperature and lower humidity, called meteorological drought.
"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.
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 concluded.