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Greenland and Climate Effect: Sun May Be Driving Key Ocean Circulation

Jul 21, 2015 06:06 PM EDT
Greenland's cycles may have differed from rest of North America's because of the sun, says new study.
This map shows the average difference in surface temperatures between 1920-1940 and 1975-1995. Gray areas indicate regions where data was insufficient to calculate long-term temperature changes.
(Photo : Credit: Takuro Kobashi)

Many changes in Greenland could potentially be traced to the sun, researchers think.

That is, in answer to the long-asked scientific question, why did Greenland cool during the 1970s through early 1990s while much of the Northern Hemisphere had rising temperatures, scientists believe they have an answer. The sun is affecting the particular ocean circulation that regulates Greenland's climate, researchers at University of Bern said recently in the journal Geophysical Research Letters.

Here's how they made their findings: The team drilled ice cores from the Greenland ice sheet, let it melt under a vacuum, then measured the argon and nitrogen gases trapped in a container to learn small changes in temperature at 10- to 20-year increments, the release said.

They learned that Greenland temperatures for the past 2,000 years have generally followed temperature shifts in the Northern Hemisphere. However, vacillations that occurred coincided with changes in the sun's energy output, they wrote in the report. 

High solar activity that started in the 1950s and continued through the 1980s had a hand in slowing ocean circulation between the South Atlantic and the North Atlantic oceans. This combined with fresh water from melting glaciers to slow warm water and air from reaching Greenland for that period, the release noted.

The type of weak solar period in which we currently find ourselves could slowly fire up the ocean circulation, driving warmer water and air toward Greenland.
If this is the case, around 2025, temperatures in Greenland could increase more than anticipated, and compounding projected sea-level rise, thinks lead author on the study Takuro Kobashi, in the release.

"We need to really consider how solar activity will change in the future," Kobashi said in the release. "If solar activity becomes really low, as scientists expect, the Greenland ice sheet will melt faster than we expected from the climate model with just greenhouse gas [warming]."

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