Climate swings in northern hemisphere linked with changes in tropics

Washington, September 26 (ANI): In a new study, scientists have found evidence that climate swings in the northern hemisphere over the past 12,000 years have been tightly linked to changes in the tropics.

The scientists found that a prolonged cold spell that caused glaciers in Europe and North America to creep forward several hundred years ago may have affected climate patterns as far south as Peru, causing tropical glaciers there to expand as well.

Glaciers in both the tropics and North Atlantic region reached their most recent maximum extents during the so-called Little Ice Age, about 1650 AD to 1850 AD, according to the scientists conducting the research.

To make the discovery, they employed a cutting-edge technique for dating glacial deposits.

"The results bring us one step closer to understanding global-scale patterns of glacier activity and climate during the Little Ice Age," said lead author Joe Licciardi, a glacial geologist at the University of New Hampshire.

By understanding how glaciers behaved in the past, the geoscientists hope to predict how parts of the world will react as the planet warms.

Human civilization arose during fairly stable temperatures since the end of the last ice age, about 12,000 years ago.

But research shows that even during this time glaciers fluctuated in large and sometimes surprising ways.

Most of the world's glaciers are now retreating, as manmade greenhouse gas levels rise.

When glaciers advance, they drag rocks and dirt with them.

When they recede, ridges of debris called moraines are left behind, and the newly exposed deposits are bombarded by cosmic rays passing through Earth's atmosphere.

The rays react with the rock and over time form tiny amounts of the rare chemical isotope beryllium-10.

By measuring the buildup of this isotope in glacial rocks, scientists can calculate when the glaciers receded.

Using this technique, the research team showed that glaciers in southern Peru moved at times similar to those in the northern hemisphere.

"The results are based on the CRONUS-Earth Project, which aims to improve measurements of these isotopes so precise ages may be assigned to 'young' glacial moraines," said Enriqueta Barrera, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.

With Peru's climate now linked to northern Europe's, the scientists plan to expand their research to other parts of the South American tropics. (ANI)