Changes in precipitation and plant cover in Europe occurred 170 years after temperatures first fell during the Younger Dryas, a period of abrupt cooling around 12,800 years ago, reports a paper published online in Nature Geoscience. The authors suggest the precipitation change only occurred once sea ice in the North Atlantic expanded far enough southwards to affect the location of the westerly winds.
Dirk Sachse and colleagues assessed the timing of temperature, hydrologic and vegetation change in a lake sediment core collected from western Germany. Annually deposited layers of sediments allowed them to count the years between the initial temperature change - as recorded by hydrogen isotopes - and changes in precipitation and vegetation, reflected by hydrogen isotopes and pollen content. They find that precipitation over the region decreased 170 years after temperatures first cooled. This reduction in precipitation was accompanied by an expansion of vegetation types accustomed to lower humidity.
In an accompanying News and Views, Ana Moreno states that "this work highlights the potential for rapid environmental change to take place over the course of just a few human lifetimes.”