Edge of the Arctic Shelf

Tom agreed to answer some questions for me about this very important body of water.

It's difficult for me to picture how much water flows through this Strait, can you put it in perspective?
"On average the transport here is about 800,000 cubic meters per second northward through this narrow (85 km) and shallow (50 m) strait. This seems like a huge amount of water, and it is, when compared to major rivers such as the Mississippi (18,000 cubic meters per second) or the Yukon (passed earlier yesterday) with an average transport of about 6,000 cubic meters per second. On the other hand, the flow through Bering Strait is merely a trickle compared to the 20 - 100 million cubic meters per second carried by major ocean currents. Thus oceanographers consider the volume of water flowing through Bering Strait to be small, while landlubbers would argue that it is tremendous. Regardless of your perspective, the flow through Bering Strait affects us all, because it has a tremendous influence on the Arctic Ocean and probably on global climate."

Could you elaborate on that? How does this little gap between the continents affect us?
"The waters flowing through Bering Strait are enriched in the nutrients (nitrogen, phosphorous, and silicon) required by phytoplankton. These nutrients come from the deep Bering Sea and fuel the tremendous biological production of the northern Bering and southern Chukchi seas. Indeed this ecosystem is amongst the most productive marine ecosystem on Earth. Some of these nutrients and plankton are carried northward across the Chukchi Sea and into the Arctic Ocean, where they feed the phytoplankton, invertebrates, and arctic cod that in turn feed whales, seals, walrus, and polar bears. In turn these mammals are an important food source for the many Siberian and Alaskan Eskimo coastal communities along the Chukchi Sea. One might speculate that these communities would not exist if Bering Strait had never been established. The strait is also a migratory pathway for a remarkably rich and diverse annual movement of plankton, marine mammals and birds over distances that bridge polar, temperate, and, for some species, tropical waters. And sadly, the strait delivers to the Arctic Ocean pollutants deposited elsewhere into the North Pacific that are eventually carried into the Bering Sea."

You mentioned the global climate. The Strait affects the climate too?
"Definitely. Let me start from the beginning, though--hang with me on this one. The waters flowing through Bering Strait are relatively fresh compared to Arctic and Atlantic Ocean waters. Within the Arctic Ocean, Bering Strait waters form a cold, fresh layer between the surface and 150 meters. That layer is important because it effectively insulates the sea ice cover from warmer (and saltier) waters found at greater depths.

Eventually the waters from Bering Strait flow across the Arctic Ocean and into the northern North Atlantic Ocean and, by so doing, play a vital role in the global hydrologic cycle. The reason for this is that evaporation exceeds precipitation in the Atlantic Ocean, while precipitation exceeds evaporation in the North Pacific Ocean. Thus Bering Strait drains some of the excess precipitation received by the North Pacific into the Atlantic Ocean. This offsets some of the freshwater lost to evaporation in this basin. Changes in the amount of freshwater transported from the Arctic Ocean to the North Atlantic Ocean are believed to play a major role in global climate change. Thus changes in the amount of freshwater carried through Bering Strait are likely important to global climate."

Many thanks to Tom for those answers.

Since there were no scientific tasks scheduled for today, it was a relaxing day. The science crew spent the day reading, watching for wildlife, typing emails to family and friends, or catching up on other research projects... and we'll need that rest, because around-the-clock science is starting up tomorrow evening!