MAN CHANGES CLIMATE.

Otago Witness, Issue 2756, 9 January 1907, Page 71

MAN CHANGES CLIMATE.

S. L. Bastin writes in the Monthly Review on the effects of civilisation upon climate. He mentions the remaikable variations of weather within a few miles' distance as an indication that local causes may produce changes in the weather. "The presence of a large number of building.' in any situation will raise the temperature of the locality, whilst the influence of the warmth arising from a large number of fires must not by any mtans be overlooked. Experiments conducted in London, Berlin, and Paris serve to show that the average annual temperature in the cities i& two or thiee degrees higher than in the ssurrounding country. At certain times of the year there is often a greater difference still, and it is noticeable that in cities sudden changes are not felt to the same extent that they are in the open country."

Taking England as a whole, there has been during the last two centuries an immense reduction in the amount of marsh

lanfl. Damp soil being always colder than dry, some change may be expected. It is actually taking place. It is a proved fact that the temperature in this country is appreciably higher than it was some centuries ago. Some old people, who might be supposed to be more sensitive to cold as they grow older, continually affirm that winters are not so severe as they used to be. The old-fashioned winter often began in December, or even November, but now it is very rarely that any prolonged spell of cold is experienced until the New Year. The writer speculates whether the'draining of the boglands of the tundras in Siberia would not alter the climate of that deso-late-region. It has been definitely, established, he says, that the presence of large numbers of trees in tropical regions tends to reduce the temperature. Belts of forest lands will also protect a ceuntry from wet and strong winds. The rainfall is said to be largely dependent on the presence of trees. Cutting down virgin forests in America has resulted in long spells of drought. Deforestation having been proved to reduce the rainfall, the question arises how far in this rainy land of ours forestation is altogether desirable. He concludes: "To sum up the whole matter, it is impossible to deny that man and his works do inuence climate to a greater or less extent ; the spread of civilisation in a new land has a real effect on the airaual tale of weather. The study of the subject is in its infancy."