Polarforskare 2012-01-19
http://www.ub.gu.se/portaler/polarportalen/biografier/ahlmann/
Han skrev om hur glaciärerna smälte på 30- och 40-talen och klimatförändringar som var på gång med den uppvärmning som var då. När The ”Sydney Morning Herald” Saturday 29 September 1951 skrev om klimatförändringarna på den tiden var det en självklarhet att citera Ahlmann.
The Sydney Morning Herald (NSW : 1842 - 1954), Saturday 29 September 1951, page 6
National Library of Australia http://nla.gov.au/nla.news-article18233023
Du kan läsa artikeln genom att klicka på länken. Men texten är lite svår att läsa så jag har kopierat av texten och justerat till den.
Don´t scoff when you hear an oldtimer say: "Summers are hotter than they used to be." This remark could once have been classed with "Stairs are steeper than they used to be, "and "Young people are wilder than when I was a boy." But today an impressive number and a lot scientists, both old and young, are convinced that the oldtimers are right.
Summers are getting warmer and, despite the unusual temperatures this year along Australia's east coast, winters generally are not as cold as they used to be. This climatic fluctuation which began a century ago and has been more noticeable in the last 20 years has been discussed since the nineteen-twenties almost exclusively in scientific circles. Recently, however, it has become a subject of more than academic interest. The scientists hasten to assure the world that there is no immediate cause for alarm. The change is merely part of the endless of heat and cold which started with the first ice age about one million years before the birth of Christ.
There is not yet reason to assume, say the scientists, that the mercury in the world's thermometers will now rise any higher than it would have risen during two or three other unusually warm periods since the beginning of our calendar. These were not years which scorched the globe as fatally as the ice ages had frozen it. But they were years of mild winters and hard summers. In some parts of Central Europe, Africa and the Americas they brought drought.
Since the turn of this century, meteorologists and their grander associates, the climatologists, have been laboriously gathering evidence of the latest change. The account of these labours from Alaskan glaciers to African lakes is as fascinating as any detective story. New seasons come gently with falling leaves, the glint of hoar, frost and the sort: of birds. New climates come spectacularly. Their harbingers are shrinking glaciers, disappearing lakes and the crunching of a moving icepack.
Dr. Hans W. Ahlmann, director of the Swedish Geographic Institute, is an authority who has spent most of his life reading these signs. A recent report based on his work shows that the new climate is coming just as surely as winter or summer. Sub-zero temperatures occur only half as frequently in northern cities as they did 75 years ago. Greenland's ice is melting and the ruins of mediaeval farmhouses hidden by icef' for centuries have already been exposed. In Spitsbergen the mean annual temperature has risen by four degrees since 1912. Ships ply the White Sea and the Gulf of Bothnia three or four weeks longer than they used to. In Iceland and the higher latitudes of Norway farmers are growing barley in soil that was once frozen for seven months each year.
But the coming of the new climate 'is most noticeable above the world's snow lines. Glaciers present the most striking evidence. The American geographer, F. E. Matthes, has reported that "glaciers in nearly all parts of the world receded regularly during the last sixty years but especially rapidly during the 1930-40 decade." All glaciers examined from Greenland through Scandinavia to Europe are shrinking. And the shrinkage is not limited to high latitudes. Some glaciers in the European Alps have vanished completely. In East Africa, the glaciers on three high volcanoes-Kilimanjaro, Mt. Kenya and Ruwenzori have- been diminishing since they were first observed in 1880. The vast Muir Glacier in Alaska's Glacier Bay has retreated a full 14 miles since 1902.
A young professor at the University of Wisconsin in the far north of the United States, Joseph Hickey, has been watching the birds of his State for the last ten years and he too, is convinced that the climate is warming up. Comparing his observations with existing records, he says that many species of American birds and mammals have moved as much as 100 miles northward over the last 40 years. The Titmouse, the Turkey Vulture, the Whip-poor-will, the Swallow and the Opossum have detected the change in the climate much more quickly than we have and have moved north to find their accustomed climatic environment.
Even the fish in the ocean know about it, too. Ahlmann reports that Eskimos are catching and eating cod, a fish that they never saw before 1900. Julian Huxley has reported that herring and haddock have been moving north off Greenland at 24 miles per year for the last 30 years. The seas themselves are changing. Sea levels rose when the glaciers of the last ice age began to melt. And now they are rising again.
One geographer reports a general rise throughout the world to the order of one millimeter (per år) during the last 30 years. Ahlmann, however, has measured a specific increase of one millimetre each year in the level of waters off Spitsbergen. That distance may be only .0,39 of one inch but geographers think it important.
Inland lakes have fared worse. With no melting glaciers to replenish them, many lakes are slowly disappearing. Dr. E. Nilsson, of Stockholm University, visited Africa in 1947 and found that the water level in Lake Victoria had fallen seven feet in the last 10 years! In America, the Great Salt Lake in Utah has lost nearly 50 per cent, of its volume since 1850. Its salt content has doubled during that time.
These cases of the Vanishing Lakes, the Shrinking Glaciers, and the Frightened Birds have now been solved and the sun stands accused. Dr. L. B. Aldrich, an astro-physicist at the Smithsonian Institute in the United States, published a report this year showing that the sun has poured enough extra heat onto the surface of the earth to affect our climate noticeably. The Danish Royal Geographical Society issued a more conservative statement. In the Danes' opinion, "the question of the cause will remain open until sufficiently exact measurements of solar radiation for a longer time are available." Other scientists, however, feel that Aldrich's data is sufficiently detailed to provide an explanation for the curious evidence of a changing climate.
Aldrich's explanation is this that the radiation of the sun has increased by one
quartet of one per cent over the last 20 years And this theory is based on 16 000 measurements made in Chile during those years Aldrich says that summer is getting warmer all the time His data has been gathered in recent years by two young American university graduates.
These young men spend two years in Chile before they arc relieved by another pair from the United States. At a weather station on Mount Montezuma, high above the Atacama Desert in Northern Chile, these observers have been measuring the unit of the sun's radiation-the solar constant. Blue enamel skies over this rugged, nitrate desert are clear the year round.
Some scientists may not yet be prepared to agree with Dr. Aldrich when he says that the solar constant is rising. But all of them, even the cautious Dane agree that something is changing our climate.
I slutet av artikeln sägs det: What effect is this having? Equally important is the economic benefit derived from increased vegetation in northern Latitudes. Barley cultivation in Iceland has already been extended, while the prospects for agriculture in northern Sweden and Finland have similarly improved. Timber is now growing beyond what was once the snow line in northern Scandinavia and Alaska. Dr. Ahlmann has pointed out another effect which the new climate may have. If the Antarctic ice regions and the major Greenland icecap should continue to melt at their present rates, he says, the surface of the ocean may rise lo catastrophic proportions. "People living in lowlands along the shores would be inundated," he warns. In a happier vein, this same scientist adds: "It is the first fluctuation in the endless series ot past and future climatic variations in the history of the earth which we can measure, investigate and possibly explain. –Slut på artikeln-
Dessa tankar på en global uppvärmning kopplad till smältande glaciärer och stigande havsnivå slutade och något annat hände. Den globala temperaturen sjönk och rädsla för att vi skulle gå mot en ny istid kom istället. Sedan blev det en period av mer upp värmning och samma tanker som fanns på 30 och 40-talen dök upp igen.
PS: När det gäller avsmältningen av gaciärer på Grönland se min bloggpost 5 maj 2011.
Den som vill läsa mer om hans forskning om smältande glaciärer lan ladda ner ett arbete av honom på
http://www.archive.org/details/glaciervariation032833mbp .Det kallas "Glacier Variations And Climatic Fluctuations" (1953/00/00)