WARMER WINTERS

Evening Post, Volume CCXV, Issue 13, 17 January 1938, Page 11

WARMER WINTERS

BRITISH EXPERIENCE

EFFECT OF GULF STREAM

About this time last year there was a dramatic conflict of expert opinion as to the probable behaviour of the 1936-37 winter, wrote E. L. Hawke, secretary of the Royal Meteorological Society, in the "Daily Mail" at the end of November. The intrepid French prophet, Abbe Gabriel, who believes that the earth's weather is made to repeat itself very closely at intervals of 372 years, foretold a winter resembling the severe one of 1564-65, when the Thames was frozen solid. As a saving clause, however, he added that this undesirable recurrence might possibly be delayed until 1937----38. , Meanwhile, the Swedish meteorologist ' Professor Sandstrom, a leading authority on the Gulf Stream and its habits, was predicting a mild, stormy season. The professor, as it turned out, hit the bull's-eye;-the Abbe, who, it must in fairness be added, had successful long-shot forecasts to his credit before his Swedish rival had been heard of, could only say, "Wait and see what happens next winter." PROPHECY REPEATED. Well, that "next winter" is here. And now Professor Sandstrom, after his annual expedition to study the vagaries of the Gulf Stream, has reiterated his prophecy of a year ago. In Northern and Western Europe, he declares, the coming winter will probably be even milder than last. So, once again, doctors differ. The Gulf Stream has long been a bone of contention among geographers and meteorologists. There are still disputes about the origin of this darkblue, highly saline river of turbulent tropical water, so warm that ships entering or leaving it have recorded temperatures differing by 30 degrees between bow and stern. According to some authorities the Gulf of Mexico, and according to others the Gulf of Guinea, provides the bulk of the current. What we do know for certain is that the main.and more rapid branch of the Stream skirts the eastern coastline of North America, while its European offshoot, called the "North Atlantic Drift," laps our own western shores as it meanders northward, at a leisurely three to five miles a day, bound for the Arctic. One school of thought holds that winters in Britain, Iceland,. and Western Scandinavia would be from 20 to 50 degrees colder than they are today were it not for the Gulf Stream; another school denies that its absence would make much difference. The truth doubtless lies, as usual, between the two extremes. COMMANDS ATTENTION. However that may be, Professor Sandstrom has satisfied himself of the Gulf Stream's potency as a controlling factor of Europe's winter weather, and the accuracy of his recent forecasts, as well as his status as a meteorologist, must command our respect. ■. . During the past few decades something or other has brought about a marked reduction in the frequency of •hard winters in. Britain and neighs -bouring Continental lands; something or other has lessened the rigour of Greenland's climate and has caused a slow dwindling in the size of the Arctic ice-cap. From the records kept by the Soviet scientists within a short distance of the North Pole since last May, it seems, too, that the weather at the extreme "top" of, the world is not so cold as it was when Nansen carried out his famous survey in the Fram towards the close of the Victorian era. There can be little doubt that a general increase in the volume and strength of the Gulf Stream has been, in the main, responsible for all this. In Professor Sandstrom's view, the best means of foreseeing the character of a" winter is to keep a finger on the Stream's pulse and a thermometer in its mouth, so to speak, during the summer and early autumn. This he has been doing for ten years or more. His findings confirm what many meteorologists had suspected long before —that a strong Gulf Stream from July to September favours, a mild winter for North-West Europe. The outlines of the mechanism can be described in a few words. Abundance of diffused tropical water in the Greenland-Iceland area makes for a high frequency of cyclone-development there, because the air warmed by contact with the Gulf Stream's imports of tepid sea is apt to be repeatedly undercut by very cold, heavy air cascading off the land masses during the long Arctic night. MILDNESS PERPETUATED. Once formed, these cyclones (or "depressions") tend to perpetuate mild weather by drawing sub-tropical air to Europe and the north-east Atlantic. Moreover, the eastward pressure of the strong south-westerly to northwesterly winds that they necessarily produce operates to prevent the westward escape, via the Baltic and Scan-dinavia,-of the intensely cold air which accumulates over. the interior of the Continent every winter. Finally, it should be pointed out that if Professor Sandstrom's expectations are again fulfilled, we shall probably suffer yet another cold, late spring next year. Excessive winter warmth of the sea in the far north causes an early break-up of the Arctic ice-pack. Premature southward drifting of the floes in February and March progressively chills the surface water in .the north-eastern corner of the Atlantic, with the result that anti-cyclones soon form there and inflict on Britain long spells of biting north-east or north winds in March and April. . The latter month, let us note, is the only one of the twelve that has given London sub-normal temperature on the average of the past five years. We may thank the Gulf Stream for our recent mild winters, but we must blame it for the-miserably cold Easter holidays which have so often followed.