Rapid Climate Change Occurs at Different Times in Different Regions

It turns out that climate change can occur extremely rapidly--at least in terms of the span of our climate history. Yet this change also occurs at different times in different regions. Scientists have discovered that on a regional scale, this rapid climate chance once occurred over different areas with a time difference of 120 years.

At the end of the last glaciation about 12,240 years before the present climate, the west German Eifel region and southern Norway became warmer. While this warming occurred about 120 years apart in the different regions, the warming was equally rapid in both areas. In order to find out about this warming, the scientists measured sediment cores from the Meerfelder Maar lake and sediments of Lake Krakenes in southern Norway.

After taking these cores, it was up to the scientists to reconstruct the climate. They had luck on their side, though. About 12,140 years ago, a major eruption of the Katla volcano occurred on Iceland. This gave researchers a time frame to work with when they encountered ash in the sediment deposits.

"It is a diligent piece of work to count and analyze thousands of these thin layers under the microscope to reconstruct climate year-by-year far back in time," said Achim Brauer, one of the researchers, in a news release.

The ash of the Katla volcanic eruption was deposited at the same time in Eifel and in Norway. Yet the sediments of the Eifel maar lake depict rapid warming about 100 years before the volcanic ash. The southern Norwegian lake sediment, in contrast, showed this warming about 20 years after the volcanic eruption. So why did this warming occur at such different times?

"We can explain this difference with the shift of hemispheric wind systems," said Brauer in a news release. "Climate changed in both regions very rapidly, but the polar front, that is the atmospheric boundary between cold polar air and the warmer air of the mid-latitudes, required more than 100 years to retreat from its glacial position at about the location of the Eifel at 50 degrees North to its southern Norwegian position at 62 degrees North."

The findings reveal a little bit more about rapid climate change and how, in particular, various regions can experience this change at different times. This has serious implications for current climate change, which may impact some areas sooner than others.

The findings are published in the journal Geology.