During the cold winter of 1717, snow fell steadily for five days in New England, lay five or six feet deep in Boston for a long time. In March 1741, people sleighed from Stratford, Conn. to Long Island across the solidly frozen Sound. In 1779-80, according to Thomas Jefferson, "the Chesapeake Bay was frozen solid from its head to the mouth of the Potomac. At Annapolis the ice was five to seven inches in thickness, quite across. . . ."
It was plenty cold in Europe last week (see p. 10), but gaffers who claim that winters were harder when they were boys are quite right—except that the change is too small to be detected except by instruments and statistics in the hands of professional meteorologists. Weather men have no doubt that the world at least for the time being is growing warmer.
A group of Soviet meteorologists, who have recorded Arctic temperatures for a decade, reported last fortnight that the Arctic is warmer. They are backed up by Harald Ulrik Sverdrup, onetime chief of Explorer Roald Amundsen's scientific staff, now head of the Scripps Institution of Oceanography in California, who found Arctic sea water warmer in 1931 than it was in 1918. The Northern Hemisphere is still recovering from the last great glaciation of the Ice Age, though for chronological purposes this period is considered to have ended some 20,000 years ago. The continental ice sheet which once covered the northern United States still exists in Greenland where it is still retreating. Despite various speculations, the reason for such climate changes is obscure.
In 1932 the U. S. Weather Bureau assembled all available records covering a century or more, found that they showed a trend towards warmth. In Manhattan, white-thatched James Henry Kimball, famed weather adviser of transatlantic fliers, found that in his territory average annual temperatures rose 2.1° from 1831 to 1900, 1.4° more from 1900 to 1938. Meteorologists do not know whether the present warm trend is likely to last 20 years or 20,000 years.