Climatic Change Causes

The causes of climatic fluctuations have not yet been fully elucidated, although many different theories have been proposed.

Some scientists believe that small variations in the Earth's orbit around the Sun (which would affect the intensity of solar radiation reaching the Earth) are the principal cause. But others have hypothesized that minute alterations in the Earth's tilt on its axis may cause the climatic belts to shift, thus changing the climate as a whole.

It has also been suggested that long- and short-term fluctuations in the Sun's activity - those caused by the 11-year sunspot cycles, for example - may affect the climate.

Changes may also occur following prolonged volcanic activity. Volcanic dust can reduce the amount of solar radiation reaching the surface, causing changes in the weather.

After the eruption of Krakatoa in 1883, for example, dust stayed in the atmosphere for three years; during this period a 10 per cent fall in solar radiation was recorded in southern France.

There is also some concern that major climatic changes may result from Man's activities, such as deforestation and pollution of the atmosphere.