Editorial Type:
Article
Article Type:
Research Article

Observed Trends in Canada’s Climate and Influence of Low-Frequency Variability Modes

L. A. Vincent Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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X. Zhang Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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R. D. Brown Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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Y. Feng Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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E. Mekis Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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E. J. Milewska Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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H. Wan Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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X. L. Wang Climate Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

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Print Publication:
01 Jun 2015
DOI:
https://doi.org/10.1175/JCLI-D-14-00697.1
Page(s):
4545–4560
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Abstract

Trends in Canada’s climate are analyzed using recently updated data to provide a comprehensive view of climate variability and long-term changes over the period of instrumental record. Trends in surface air temperature, precipitation, snow cover, and streamflow indices are examined along with the potential impact of low-frequency variability related to large-scale atmospheric and oceanic oscillations on these trends. The results show that temperature has increased significantly in most regions of Canada over the period 1948–2012, with the largest warming occurring in winter and spring. Precipitation has also increased, especially in the north. Changes in other climate and hydroclimatic variables, including a decrease in the amount of precipitation falling as snow in the south, fewer days with snow cover, an earlier start of the spring high-flow season, and an increase in April streamflow, are consistent with the observed warming and precipitation trends. For the period 1900–2012, there are sufficient temperature and precipitation data for trend analysis for southern Canada (south of 60°N) only. During this period, temperature has increased significantly across the region, precipitation has increased, and the amount of precipitation falling as snow has decreased in many areas south of 55°N. The results also show that modes of low-frequency variability modulate the spatial distribution and strength of the trends; however, they alone cannot explain the observed long-term trends in these climate variables.

Denotes Open Access content.

Corresponding author address: Lucie Vincent, Climate Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto ON M3H 5T4, Canada. E-mail: lucie.vincent@ec.gc.ca

Abstract

Trends in Canada’s climate are analyzed using recently updated data to provide a comprehensive view of climate variability and long-term changes over the period of instrumental record. Trends in surface air temperature, precipitation, snow cover, and streamflow indices are examined along with the potential impact of low-frequency variability related to large-scale atmospheric and oceanic oscillations on these trends. The results show that temperature has increased significantly in most regions of Canada over the period 1948–2012, with the largest warming occurring in winter and spring. Precipitation has also increased, especially in the north. Changes in other climate and hydroclimatic variables, including a decrease in the amount of precipitation falling as snow in the south, fewer days with snow cover, an earlier start of the spring high-flow season, and an increase in April streamflow, are consistent with the observed warming and precipitation trends. For the period 1900–2012, there are sufficient temperature and precipitation data for trend analysis for southern Canada (south of 60°N) only. During this period, temperature has increased significantly across the region, precipitation has increased, and the amount of precipitation falling as snow has decreased in many areas south of 55°N. The results also show that modes of low-frequency variability modulate the spatial distribution and strength of the trends; however, they alone cannot explain the observed long-term trends in these climate variables.

Denotes Open Access content.

Corresponding author address: Lucie Vincent, Climate Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto ON M3H 5T4, Canada. E-mail: lucie.vincent@ec.gc.ca
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