The long history of severe droughts across Europe and the Mediterranean has largely been told through historical documents and ancient journals. Now, for the first time, an atlas based on scientific evidence provides the big picture, using tree rings to map the reach and severity of dry and wet periods across Europe, and parts of North Africa and the Middle East, year to year over the past 2,000 years.
A paper describing the new atlas, coauthored by scientists from 40 institutions is released.
The new drought atlas could also improve understanding of climate phenomena like the Atlantic Multi-decadal Oscillation, a variation in North Atlantic sea-surface temperatures that hasn’t been tracked long enough to tell if it is a transitory event, forced by human intervention in the climate system, or a natural long-term oscillation.
Authors compare results from the new atlas and its counterparts across three time spans: the generally warm Medieval Climate Anomaly (1000-1200); the Little Ice Age (1550-1750); and the modern period (1850-2012).
The drought atlas provide a much deeper understanding of natural climate processes than scientists have had to date.
The hemispheric scale adds to the potential uses of what was already the gold standard of paleo-hydroclimate research. The fact that the drought atlases provide a nearly hemispheric view of hydroclimate variability provides an incredible amount of information that can be used to better understand what was happening in the atmosphere and ocean.
The atlas also tracks the reach of the great European famine of 1315-1317, when historical documents describe how excessive precipitation across much of the continent made growing food nearly impossible. The atlas tracks the hydroclimate across Europe and shows its yearly progressions from 1314 to 1317 in detail, including highlighting drier conditions in southern Italy, which largely escaped the crisis.
The atlas may also help shed light on more recent phenomena, including a record 2006-2010 drought in the Levant that a recent Lamont study suggests may have helped spark the ongoing Syrian civil war.
The tree ring data used to create the new atlas included cores from both living trees and timbers found in ancient construction reaching back more than 2,000 years. They come from 106 regional tree ring chronologies, each with dozens to thousands of trees, and were contributed to the project by the International Tree Ring Data Bank and European tree-ring scientists.
The North America atlas, published in 2004, has been used by other researchers to suggest that a series of droughts starting around 900 years ago may have contributed to the eventual collapse of native cultures. Likewise, the Asia atlas, published in 2010, has led researchers to connect droughts, at least in part, to the fall of Cambodia’s Angkor culture in the 1300s, and China’s Ming dynasty in the 1600s.