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Global Change and Thermal History as Recorded by Northern North American Tree-Ring Data,

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Thermal regimes and heat exchange of the Polar and subpolar regions play a key role in global climatic change. Principal components analysis of instrumental data for the globe indicate that northern high latitude temperatures are a very strong component of global temperature variations. Tree-ring data from thermally responsive sites in Canada and Alaska yield records of polar and subpolar temperature changes for centuries prior to the relatively short period of instrumental measurements. Tree-ring width based reconstructions of Arctic and northern North American temperatures through 1973 reflect the general positive trend in large-scale instrumental data over the past century. These reconstructions, as well as the raw tree-ring measurements, show that this recent period of warming is unusual relative to the prior few centuries. More recently developed data from Canada confirm previous reconstructions. A maximum latewood density chronology from the Northwest Territories shows a stronger climatic response to warm-season temperatures than ring width data from the same trees. The density information also shows a response to several other temperature-related parameters, including ground-level solar radiation measurements. In detecting and quantifying global climatic change, tree-ring analysis of high latitude trees provides evidence of recent wide-scale warming in northern North America. This warming will affect boreal forests, northern waters, and human activities. However, more studies are needed to better determine the extent of recent and possible future climatic change and the resulting environmental consequences.

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  • Geography
  • Meteorology
  • Forestry
  • Snow, Ice and Permafrost

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