Newsletter No.6 March-1999

Motoyoshi Ikeda
Professor of Hokkaido Univ.
IARC Program Director,FRSGC

The climate change research on the Arctic region is very important for understanding and predicting global warming.

The key to solve the global warming issue seems to be found within the research. Many scientists have been insisting that the effects of global warming appear predominantly in the Arctic Ocean/region. However in the following figure I would like to explain a mechanism, in which the phenomena do not always agree with this supposition.

In this figure, all of the oceans on the Earth are extended from the Arctic Ocean through the Greenland Sea, the Atlantic Ocean, the South Pacific and the North Pacific Oceans. Namely, all the ocean currents are expressed in this plane. For example, fresh water flows into the Arctic Ocean from Russian rivers, and as a result, the less saline surface water is cooled by the atmosphere, and sea ices are created. They sometimes go out of the Arctic Ocean into the Greenland Sea by winds and/or ocean currents. In fact the Greenland Sea is thought to be a very important sea area, which we now observe most carefully. There, more saline, and high temperature seawater flows from the Atlantic Ocean, and collides with less saline, low temperature sea ices/ocean currents from the Arctic Ocean in the Greenland Sea. The heat-losing seawater, being cooled by the atmosphere, increases in density, and there occurs sinking. This is called deep-layer water (deep-layer water in the North Atlantic Ocean), which flows into deep layers in the oceans all over the world.

However, as the amount of water flowing out of Russian rivers increases and the ice in the Arctic ocean melts, so the flow of sea ice swells and surface water in the Greenland Sea becomes less saline. The surface water does not contain enough salinity and so cannot reach enough density to sink there. Then sinking of the water stops. Consequently high temperatures and more saline water coming through the Gulf Stream also stop moving. That is to say, the following phenomena occurs: that heat transportation by the Gulf Stream decreases, and the climate in the north Atlantic region becomes colder than the present. At present they say that the temperature in the Arctic region will become higher due to the global warming, but I am afraid that the period of increased cold in its surrounding area would last for several decades. There remains some evidence that there occurred, in a large scale, such kind of phenomena after the end of the ice age.

As mentioned above, I will proceed with the research on the Arctic region, which has an important role in the global warming, at the International Arctic Research Center (IARC). I think this is a good opportunity for Japanese researchers to test their knowledge, as they have not taken much of a the leadership role in international researches.

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