Scientists are watching the Arctic Ocean closely and measuring the growing amount of freshwater to see how it could affect the Earth's climate. "Changing Planet" is produced in partnership with the National Science Foundation.
Fresh Water in the Arctic
ANNE THOMPSON, reporting:
The Arctic can be a harsh and forbidding place. But this ice-covered ocean, the Earth's smallest, is feeling big impacts from a warming world – with scientists recording unprecedented changes in the balance of fresh and salt water.
RICHARD KRISHFIELD (Woods Hole Oceanographic Institution): The Arctic is a key. I mean, it's one of the places that is very sensitive to climate change. It's likely to respond, you know, very extremely to climate change.
THOMPSON: Rick Krishfield is part of a scientific team documenting what's happening in the Arctic Ocean. His annual trips to record water temperatures and the amount of salt in the water are supplemented by daily emails from buoys he left behind, sending data twice a day to his laboratory at the Woods Hole Oceanographic Institute in Massachusetts.
The buoys are deployed in an area called the Beaufort Gyre. It's the dominant current in the Arctic, slowly moving and mixing the waters, including a massive amount of fresh water from northern rivers and the Bering Strait.
THOMPSON: What's happening up in the Arctic Ocean, some 5,000 miles north of Woods Hole, could have a big impact on the climate here, and along the Eastern Seaboard of the United States.
In the Arctic, cold, fresh water sits on the surface of the ocean, protecting the polar ice from the warmer water below. The clockwise circulation of the Beaufort Gyre traps that freshwater in place up north. But periodically the Gyre weakens, releasing some fresh water south. If the Gyre releases too much fresh water, it can flow into the North Atlantic and act as a barrier, keeping warmer Gulf Stream water from releasing its heat into the atmosphere. Arctic Group leader Andrey Proshutinsky says too much fresh water there could impact the climate of the entire northern hemisphere, putting a chill in North America and Europe.
Dr. ANDREY PROSHUTINSKY (Woods Hole Oceanographic Institution): And that's why we have to know how much fresh water we have in this upper layer. If we have too much, heat cannot penetrate to atmosphere, and atmosphere is getting colder and climate is cooling.
THOMPSON: So, the fresh water, in effect, is a blanket?
PROSHUTINSKY: This is--yeah, this is--works like a blanket. So if you interrupt this flow of heat, or cover it with blanket of fresh water, we will observe cooling.
THOMPSON: In his younger days, Proshutinsky flew on some of the earliest Soviet missions to unexplored areas of the Arctic. Science has come a long way since then, but doing research in the Arctic is still extremely difficult, and people still can't make observations there year-round.
THOMPSON: To track the daily course of fresh water, scientists and engineers went back to the drawing board. They developed new instruments to give them information they could only guess at until now.
The team at Woods Hole developed the “ITP,” or Ice-Tethered Profiler, a yellow buoy that they've successfully deployed on the Arctic ice year round. It's neat, compact, and only occasionally attracts the stray polar bear.
RICHARD KRISHFIELD: Polar bears are known to frequent whatever buoys and things that they can find on the ice. And they're gonna grab ‘em and they’re gonna bite ‘em, and they’re gonna see if they're edible or not. And this guy, apparently, you can see, punctured it with his claws a few times here. And then he ripped some chunks out of it to see whether it tasted good or not.
THOMPSON: The ITP sends an instrument 700-meters, or about 23-hundred feet, up and down a wire deep in the Arctic water, taking measurements every 25 centimeters, or about 10-inches, recording water temperature and salt content. The data shows that fresh water has been accumulating dramatically in the Arctic Ocean over the last twelve years.
KRISHFIELD: The redder contours mean that it's more fresh water. The bluer means less.
THOMPSON: Wow, look at the difference there, 2005 and 2009, just in four years.
THOMPSON: A build up Proshutinsky finds alarming.
PROTUSHINSKY: Ocean accumulates fresh water and releases, accumulates and releases. But if it is unbalanced, it's possible that too much fresh water will be released. And in this case, we can have some dramatic changes in climate.
THOMPSON: Is the Arctic Ocean out of balance?
PROSHUTINSKY: Right now, it's at a very unstable situation.
THOMPSON: Scientists admit they don't understand everything about the impact that Arctic fresh water could have on global climate. But they do know that how the ocean responds to the threat of climate change will depend on the delicate balance of air, sea and ice at the top of the world.
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