A conveyor belt of ocean water that loops the planet and regulates global temperatures could be heading for a tipping point.
Sea ice over the Greenland Sea near northeast Greenland. Arctic sea ice this summer was the second lowest on record, and ocean changes in the Arctic could dramatically change the climate for much of the rest of the planet.
THE HIGH ARCTIC, ABOARD THE R.V. KRONPRINS HAAKONSummer sea ice has been shrinking so dramatically here in the Fram Strait, high in the Arctic between Norway and Greenland, that researchers who make this trip annually point out missing patches like memories of departed friends.
“The first time I was here, in 2008, you could walk on the ice,” says Norwegian Polar Institute (NPI) oceanographer Paul Dodd, gesturing from the deck of this research icebreaker toward the spot, near the Prime Meridian, where his team is about to take samples for temperature, salinity, dissolved carbon, and other chemical measurements of what is now open water. It’s dotted with only a few random, battered-looking ice drifts.
Temperatures are rising and ice is melting all over Earth. But this place is special: The ocean changes that are happening right here could dramatically alter the climate for much of the rest of the planet.
Fram Strait and the waters to the south, in the Greenland, Norwegian, and Irminger seas, make up the control room of a global “conveyor belt” of currents that stretches the length of the planet. Only in this region and one other, in the Antarctic, does water at the sea surface become heavy enough—dense with cold and salt—to sink all the way to the seafloor and race downhill along the deepening ocean bottom. That sinking powers the conveyor, known as the Atlantic meridional overturning circulation, or AMOC—which in turn regulates temperatures and weather around the world.
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