Ocean Forces Threaten Our Climate

The warm water that is so important to Europe actually comes from the other side of the world, in the Pacific Ocean. This tepid stream, flowing unseen through the oceans, is the longest river in the world. It flows along the surface, both because it is warm (and warm water, like warm air, rises) and because it is less salty ‚ and so less dense - than the deeper water. The warm waters travel westward from the central Pacific, past the north coast of Australia and round the southern tip of Africa before moving up into the Atlantic.

The present state of the 'ocean conveyor belt' that transfers warm, less salty water from the Pacific to the Atlantic as a shallow current, and returns cold, more salty water from the Atlantic to the Pacific as a deep current flowing further south. This flow is threatened by melting ice in the Arctic, and disruptions off the Antarctic coast.

photo - Pioneer Online Ltd.

This great ocean river becomes the Gulf Stream by the time it heads up through the North Atlantic. But as the current surges past Europe, its nature begins to change. It cools down significantly as it gives up its precious heat to the European seaboard. And, all along its long journey, the warmth of this invisible river has encouraged water to evaporate from its surface layer, so it becomes increasingly salty. Around the latitude of Iceland, the moving stream becomes so dense that it sinks into the depths.

This stream now becomes a cold river, flowing back along the ocean floor. Rounding the south of Africa and Australia, it returns to the Pacific, where it is pushed to the surface and warms to complete the cycle. The whole effect is like a conveyor belt bringing Pacific warmth to the North Atlantic.

The ocean conveyor belt has run more or less smoothly since the end of the last Ice Age. But global warming may now throw a spanner into its workings. The planet is undoubtedly warming up, even if people still argue about how much of this is due to human activities, and the extra heat is melting ice in the Arctic Ocean. The ice turns into fresh water, which flows into the salty North Atlantic.