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Urban-induced Increase in Length of the Freeze-free Season and Its Environmental Implications

Published online by Cambridge University Press:  24 August 2009

Lawrence C. Nkemdirim  and
D. Venkatesan
Lawrence C. Nkemdirim
Affiliation:
Department of Geography, University of Calgary, Calgary, Alberta T2N 1N4, Canada
D. Venkatesan
Affiliation:
Department of Physics, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Extract

There has been a systematic increase in the length of the freeze-free season in several Canadian cities since 1940. This increase is believed to be due mainly to urbanization. Although the rate of urbanization during the period 1940–70 was not significantly higher than the rates in the preceding decades, urban growth during those thirty years was accompanied by higher levels of fossil-fuel conversion, which produced higher temperatures in towns and cities than in surrounding rural areas, and a generally reinforced ‘greenhouse effect’. The higher temperatures in turn combined with other urban factors to enhance the length of the freeze-free season.

In a northern climate where the growing-season is already precariously short, a longer freeze-free season should have beneficial effects on agriculture and affect other aspects of the environment. There is general agreement among research workers that the energetics of solar variability are too small to affect tropospheric or stratospheric processes directly to any significant degree. This study reinforces belief in the importance of local factors; such influences tend to override any subtle connection between solar variability and the weather.

Type
Main Papers
Information
Environmental Conservation , Volume 13 , Issue 4 , Winter 1986 , pp. 347 - 350
Copyright
Copyright © Foundation for Environmental Conservation 1986

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