Interpreting the meteorology of the late and post-glacial
Abstract In Baltic lands the Late Glacial “Allerod Oscillation” of North European climate has been recognized through its effects for upwards of 50 years and later confirmed in Britain. Studies of glacier behaviour in association with climatic fluctuations supported the probability that evidence for contemporary Late Glacial climatic oscillations should be found in other continents. About 1950 it began to appear from pollen analysis supported by early radiocarbon dating that a similar episode occurred in eastern North America. Subsequently, more detailed studies in the longitude of the Upper Great Lakes have failed to support the occurrence of a climatic recession precisely contemporary with that in northwest Europe. Assemblage of dates with regard to the Late Glacial on a global scale is now possible and Dr. J. H. Mercer from Ohio University has recently argued that the climatic episode represented by the Allerod oscillation is virtually confined in its effects to Europe. He offers an explanations based on the consequences of the probable behaviour of the Arctic ice. Recent developments in knowledge of the behaviour of the high-altitude wave pattern in the upper westerlies allow for a reconciliation of the controversial evidence with regard to the character and timing of apparent climatic anomalies in differing longitudes. The Allerod oscillation should not be expected to be world-wide in its effects, or even in the Northern Hemisphere. Recent studies in northern Canada of the chronology of peat growth lend support to the view that a small but persistent change of the atmospheric circulation might cause the vegetation to register climatic effects differing considerably between, say, northern Manitoba and eastern Labrador. Further results from Siberia would be helpful.