Test Design Lighthouse

In most maritime regions, the major currents are largely uninfluenced by local winds. Just like giant conveyors, they transport enormous volumes of water from North to South, from East to West, and enormous amounts of heat energy are distributed with the water.

Water is a much more efficient heat storage medium than air. In global climatic terms, the oceans not only store heat, they distribute it as well. The surface water heated up by the high levels of solar irradiation in the tropical and subtropical regions flows northwards and southwards, rendering the climate in the temperate and polar areas milder. A special feature of the Atlantic is the northwards flow of heat energy seen in both hemispheres in this ocean, the most important part of which in the northern hemisphere is the Gulf Stream. About one thousand million megawatts of heat energy are transferred to western and northern Europe in this way. Without this phenomenon, the winter in central Europe would be as cold as it is in northern Canada.

In the ocean region between Greenland and Norway, the waters of the Gulf Stream cool appreciably, becoming denser and heavier in the process. In the Greenland Sea, this water sinks: In columns only 15 kilometres wide, up to 17 million cubic metres of water per second sink to depths of around 2,000 metres. The effects of the rush of surface water to replace these sinking currents are felt throughout the Atlantic and on into the Indian and Pacific Oceans. This mechanism is also a reciprocal driving force sustaining the Gulf Stream.

The worst threat posed by the greenhouse effect would have direct consequences here: If global warming melts increasing amounts of glacial and polar cap ice, the saline concentration of the water will drop, making the water in the Greenland Sea lighter, so that it will no longer sink, vitiating the natural engine driving the Gulf Stream. Thus global warming would lead - astonishingly enough - to a colder European climate.