Global Warming May Not End up Being Warm at All

Most scientists are now certain that global warming is taking place. Gases such as carbon dioxide produced by burning of coal, oil, wood, together with industrial pollution, are creating a warm blanket around the earth. This blanket is trapping heat in the atmosphere (the process known as "the greenhouse effect"), and so raising the temperature of the earth (global warming).

The evidence for global warming can now be seen in the world's changing climate statistics. In Europe, eight of the last ten years have seen record high temperatures. For northern Europe, this has generally been a change for the better. Gardeners can now even grow some tropical plants in England, though London may never see a "White Christmas" again. On the other hand, the countries around the Mediterranean Sea, and those south of the Sahara desert are receiving even less rain than before. In sub-Saharan Africa the crops are drying out in the fields and people are dying of starvation. In the Americas, the climate is becoming more extreme—the summers are getting hotter and the storms are becoming more violent. In 1999 the southern United States was struck by a series of destructive hurricanes, while the end of 1999 saw the worst floods ever in Venezuela. Meteorologists expect such trends to continue, and indeed to worsen, if global warming cannot be halted.

In addition to worrying about rising global temperatures and more extreme weather conditions, scientists are closely monitoring sea levels around the world. These are slowly rising, as the northern and southern polar ice caps start to melt. This will have serious consequences for low-lying countries near the sea, such as the coral islands in the Pacific, and Bangladesh where the River Ganges already floods the delta every year. Already parts of these places are disappearing under the rising tides.

According to new research, one contradictory feature of global warming is that it will probably lead in the end to a period of much colder weather, at least in Europe. Scientists base their theory on what happened the last time the world warmed up, 8,300 years ago. They have discovered that when the ice melted from the northern polar ice cap it became trapped in an enormous lake in northern Canada. As more ice melted this lake suddenly burst open, releasing millions of tons of freezing fresh water into the North Atlantic. This flood of water was so large that it prevented the normal flow of water in the Atlantic, which takes warm water from the tropics north to Europe. When this flow of warm water was cut off, temperatures in Europe dropped by between three and eight degrees Celsius over the next two hundred years. Scientists believe that a similar process could occur in the next century if the Greenland Ice Sheet starts to melt. "Ultimately, that's the interest here," says Richard Alley, an American climate expert. "The climate hasn't varied much in 8,000 years. But the big changes could come back!"