September 2, 2009

Geologist solves an Asian glacial mystery

A U.S. geologist says he has determined how a group of glaciers advanced in the Southeast Himalayas 9,000 years ago, despite hotter Central Asian summers.

Brigham Young University scientist Summer Rupper said the glaciers advanced from 1 to 3 miles while most other Central Asian glaciers were retreating.

Stronger monsoons were thought to be responsible, said Rupper, Our research indicates the extra snowfall from monsoonal effects can only take credit for up to 30 percent of the glacial advance.

As Central Asia's summer climate warmed as much as 6 degrees Celsius, shifting weather patterns brought more clouds to the Southeast Himalayas, Rupper said, noting the additional shade created a pocket of cooler temperatures. Temperatures also dropped when higher winds spurred more evaporation.

Rupper said such seemingly anomalous glaciers underscores the important distinction between the terms climate change and global warming.

Climate change is any long-term change in the statistics of weather over periods of time ranging from decades to millions of years, Wikipedia said, while global warming is the increase in the average temperature of the Earth's near surface air and oceans since the mid 20th century.

Even when average temperatures are clearly rising regionally or globally, what happens in any given location depends on the exact dynamics of that place, Rupper said.

The study that included Gerard Roe and Alan Gillespie of the University of Washington appears in the journal Quaternary Research.