A Multi-Millennial Context for the Modern Droughts in the Fertile Crescent

The ancient Fertile Crescent—a quarter-moon shaped region stretching from the Persian Gulf to the eastern Mediterranean, what is now modern-day Iraq, Syria, Jordan, Lebanon, Israel and northern Egypt, has been home to some of the world's oldest civilizations. The region has been struck by several multi-year droughts in the last two to three decades and the seasonal precipitation over the region has declined by as much as 15% over the last 100 years. Furthermore, some climate models suggest that the current drying trend may well persist into the future so much so that the entire 'Fertile Crescent' may "disappear" by the turn of this century. Here we assess the severity of modern droughts and the drying trend in the longer context of its regional hydroclimate variability over the past four millennia. We have developed a high-resolution history of climate change in the Fertile Crescent using temporal variations in speleothem oxygen and carbon isotopes from Kuna Ba Cave in northern Iraq. Our records reveal a wide spectrum of hydroclimate variability characterized by multi-centennial trends and quasi-oscillatory variability with several step-like shifts in the mean climate. Importantly, our data indicate that the severity of modern droughts in the region has likely surpassed all of the previous (inferred) droughts in the region over the last four millennia. These observations imply a possible role of anthropogenic forcing in shaping the modern climate trends in the Fertile Crescent.