SYDNEY, Aug. 10 (Xinhua) -- Giant ice sheets covering much of North America during the last ice age altered rainfall patterns in Australia, despite being thousands of kilometers away, a new study shows.
Researchers found that the height of the North American ice sheets produced the biggest changes in atmospheric circulation, redirecting winds across the globe and shifting the tropical rainfall belt southward, according to a release by Australia's University of New South Wales on Monday.
This southward shift strengthened the circulation that drives Australia's summer monsoon, increasing summer rainfall across much of Australia while reducing rainfall in parts of Indonesia and Papua New Guinea, it said.
The study, published in Climate of the Past, focuses on a climate about 49,000 years ago during the last ice age, when atmospheric carbon dioxide levels were very low and large ice sheets covered parts of North America and northern Europe.
The giant ice sheets in North America were not yet as large as when they reached their peak around 21,000 years ago, but they were already large enough to influence climate far beyond their edges.
Building ice sheets of this size required enormous amounts of water. As more water from the oceans became locked away as ice on land, sea levels fell by around 60 meters, exposing underwater landscapes, joining Australia and New Guinea into a single landmass known as Sahul, the study noted.
These results show that changes in one part of the world can trigger responses thousands of kilometers away through the atmosphere, the researchers said. ■