May 5, 2009

Glacier growth differs between hemispheres

U.S. scientists say that while the majority of the world's glaciers are retreating as the planet becomes warmer, glaciers south of the equator are growing.

The researchers at Columbia University's Lamont-Doherty Earth Observatory said they discovered glaciers in South America and New Zealand are inching forward, pointing to strong regional variations in climate.

Conventional wisdom holds that during the era of human civilization, climate has been relatively stable. The scientists said their findings are the latest to challenge that view, showing New Zealand's glaciers have gone through rapid periods of growth and decline during the current interglacial period known as the Holocene.

New Zealand's mountain glaciers have fluctuated frequently over the last 7,000 years, and glacial advances have become slightly smaller through time, said Joerg Schaefer, lead author of the study. This pattern differs in important ways from the northern hemisphere glaciers. The door is open now towards a global map of Holocene glacier fluctuations and how climate variations during this period impacted human civilizations.

The Holocene is a geological time period that began about 11,700 years ago and continues to the present.

The research is detailed in the journal Science.