Water-free Bering Strait Influenced Climate Cycles, Study Says

The appearance and disappearance of a land bridge across the Bering Strait as sea levels rose and fell played an important role in global climate cycles from 116,000 years ago to 34,000 years ago, according to a new study. The study, conducted by scientists at the U.S. National Center for Atmospheric Research, said that as the climate cooled because of changes in the Earth’s orbit, northern ice sheets expanded, causing sea levels to drop. Falling sea levels opened up a land bridge between Asia and North America across the Bering Strait, which altered ocean currents by choking off the supply of relatively fresh north Pacific water through the Arctic Ocean to the Atlantic Ocean. The Atlantic then grew saltier and denser, which changed ocean circulation patterns, bringing warmer water north from the tropics. That warmth melted ice sheets, which caused sea levels to rise, inundating the Bering Strait. That, in turn, sent fresher water from the Pacific into the Arctic and Atlantic Oceans, which once again changed oceanic circulation patterns and cooled the Arctic, setting the entire cycle in motion again. That cycle was broken 34,000 years ago when the Earth’s orbit placed it far from the sun, ushering in the last Ice Age. One researcher said the study, published in the journal Nature Geoscience, showed that “even small processes, if they are in the right location, can amplify changes in climate around the world.”