Scientists predict future impacts of climate change using oceanographic data

Washington, Nov 9 : Ecologists and oceanographers have predicted the future impacts of climate change by reconstructing the past behavior of Arctic climate and ocean circulation.

The research team comprised of Charles Greene of Cornell University and colleagues, who reconstructed the patterns of climate change in the Arctic from the Paleocene epoch to the present.

Over these 65 million years, the Earth has undergone several major warming and cooling episodes, which were largely mitigated by the expansion and contraction of sea ice in the Arctic.

"When the Arctic cools and ice sheets and sea ice expand, the increased ice cover increases albedo, or reflectance of the sun's rays by the ice," said Greene, the lead author on the paper. "When more of the sun is reflected rather than absorbed, this leads to global cooling," he added.

Likewise, when ice sheets and sea ice contract and expose the darker-colored land or ocean underneath, heat is absorbed, accelerating climate warming.

Currently, the Earth is in the midst of an interglacial period, characterized by retracted ice sheets and warmer temperatures.

In the past three decades, changes in Arctic climate and ice cover have led to several reorganizations of northern ocean circulation patterns.

"When Arctic climate changes, waters in the Arctic can go from storing large quantities of freshwater to exporting that freshwater to the North Atlantic in large pulses, referred to as great salinity anomalies (GSA)," Greene explained.

"These GSAs flow southward, disrupting the ocean's circulation patterns and altering the temperature stratification observed in marine ecosystems," he added.

The team reported that if current patterns of change in the Arctic and North Atlantic Oceans continue, alterations of ocean circulation could occur on a global scale, with potentially dramatic implications for the world's climate and biosphere.

"If the Earth's deep ocean circulation were to be shut down, many of the atmospheric, glacial and oceanic processes that have been stable in recent times would change, and the change would likely be abrupt," said Greene.

"While the ecosystem consequences of gradual changes in the ocean are somewhat predictable, all bets are off after such abrupt changes occur," he added.

"This research presents a compelling example of how climate change has altered marine ecosystems," said David Garrison, director of the National Science Foundation (NSF)'s Biological Oceanography Program, which funded the research.

"It illustrates the value of basic research in understanding the underlying mechanisms and consequences of rapid climate change," he added.

ANI