Water Cycle Amplifies Abrupt Climate Change

It turns out that the water cycle might have more of a role when it comes to climate change than scientists first thought. Researchers have discovered that the water cycle was the main driver of widespread environmental change in western Europe during the Younger Dryas period 12,680 years ago.  The findings could have implications for climate change today.

The Younger Dryas period was the last major cold period at the end of the last glaciation. It lasted for about 1,100 years when an abrupt change in the pathway of the westerly wind systems over Europe led to massive environmental change within a few, short years.

In order to better understand what might have driven the abrupt cooling of the Younger Dryas period, the researchers analyzed organic remains extracted from Meerfelder maar lake sediments in western Germany. More specifically, the researchers extracted molecular organic remains from plant fossils that were extracted from the precisely dated sediments. This allowed them to reconstruct changes in precipitation patterns in detail.

So what did they find? It turns out that there was an intrusion of dry polar air into western Europe that led to the collapse of local ecosystems and resulted in the observed widespread environmental changes.

"In our new study we can show for the first time that this change in the pathway of westerly wind systems brought dry polar air into western Europe and this was the ultimate cause for the widespread disappearance of forests in the area," said Dirk Sachse, one of the researchers, in a news release.

The findings reveal a little bit more about how climate change can be drastically impacted by atmospheric circulation patterns. Yet these patterns were changed by the southerward expansion of the sea ice in the North Atlantic following the onset of cooling. This led to a southward shift of the polar front channeling the air.

The findings are published in the journal Nature Geoscience.