Hot and Cold Running Oceans

How can we believe the news about global warming when the eastern half of our country is blanketed in snow with the coldest temperatures in recent memory? Evidence shows that the Arctic ice cap is melting and the glaciers on Greenland are shrinking at an alarming rate. When the disappearing ice exposes the water at the pole, two conditions result: first, evaporation of the water takes place bringing more snow to the areas to the south, namely Canada and the northern United States; secondly, the ice that previously reflected heat back into the atmosphere is gone allowing more heat to be absorbed into the water. As the ice cap and glaciers melt, fresh water mixes with salt water so that the northern oceans become less salty.

To explain the effect of the fresher water one needs to realize that the Gulf Stream, dominating the flow in the Atlantic Ocean, resembles a conveyer belt with cold water off the coasts of Labrador and Greenland, sinking as it meets warmer waters to the south. This cold salt water flow travels southward at depth along the eastern coast of North America, warming as it mixes with tropical waters. Then this warm water is propelled northward as the top layer of the conveyer belt. Thus the Gulf Stream travels toward northwest Europe bringing warm weather to that area. When we realize that London and Paris are at the same latitude as Labrador, the effect of the Gulf Stream warmth is vital to the survival of northern Europe.

Fresh water is not a dense as salt water and thus will not sink as readily. This could weaken and eventually shut down the belt of water driving the Gulf Stream. Once this happens, it cannot be restarted. Europe would be plunged into another ice age.

We are at a critical point in our climate history. Understanding these changes help us make choices vital to protect our planet as we know it.—Gene Kaula-Slater

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