Recent studies have shown that, since 1900, mean annual temperature over southern Canada has increased by an average of 0.9°C, with the largest warming during winter and early spring. Every season was associated with greater increases in minimum temperature as opposed to maximum, thus resulting in a significant decrease in the daily temperature range (DTR). The second half of the twentieth century was associated with significant winter and spring warming in the south and west, and cooling in the northeast. However, no significant changes in DTR were observed during this period. This investigation goes beyond the annual/seasonal scales by examining trends and variability in daily minimum and maximum temperature with particular emphasis on extremes. Using recently updated, homogenized daily data, spatial and temporal characteristics of daily and extreme temperature-related variables are analyzed on a seasonal basis for the periods of 1900–98 (southern Canada), and 1950–98 (the entire country). From... Abstract Recent studies have shown that, since 1900, mean annual temperature over southern Canada has increased by an average of 0.9°C, with the largest warming during winter and early spring. Every season was associated with greater increases in minimum temperature as opposed to maximum, thus resulting in a significant decrease in the daily temperature range (DTR). The second half of the twentieth century was associated with significant winter and spring warming in the south and west, and cooling in the northeast. However, no significant changes in DTR were observed during this period. This investigation goes beyond the annual/seasonal scales by examining trends and variability in daily minimum and maximum temperature with particular emphasis on extremes. Using recently updated, homogenized daily data, spatial and temporal characteristics of daily and extreme temperature-related variables are analyzed on a seasonal basis for the periods of 1900–98 (southern Canada), and 1950–98 (the entire country). From...

Precipitation responses over Canada associated with the two extreme phases of the Southern Oscillation (SO), namely El Niño and La Niña, are identified. Using the best available precipitation data from 1911 to 1994, both the spatial and temporal behavior of the responses are analyzed from the El Niño/La Niña onset to several seasons afterward. Composite and correlation analyses indicate that precipitation over a large region of southern Canada extending from British Columbia, through the prairies, and into the Great Lakes region is significantly influenced by the SO phenomenon. The results show a distinct pattern of negative (positive) precipitation anomalies in this region during the first winter following the onset of El Niño (La Niña) events. During this same period, significant positive precipitation anomalies occur over the northern prairies and southeastern Northwest Territories in association with El Niño events. Statistical significance of the responses is tested by the Student’s t-test a... Abstract Precipitation responses over Canada associated with the two extreme phases of the Southern Oscillation (SO), namely El Niño and La Niña, are identified. Using the best available precipitation data from 1911 to 1994, both the spatial and temporal behavior of the responses are analyzed from the El Niño/La Niña onset to several seasons afterward. Composite and correlation analyses indicate that precipitation over a large region of southern Canada extending from British Columbia, through the prairies, and into the Great Lakes region is significantly influenced by the SO phenomenon. The results show a distinct pattern of negative (positive) precipitation anomalies in this region during the first winter following the onset of El Niño (La Niña) events. During this same period, significant positive precipitation anomalies occur over the northern prairies and southeastern Northwest Territories in association with El Niño events. Statistical significance of the responses is tested by the Student’s t-test a...

Droughts have been recorded all across Canada and have had significant impacts on individuals and communities. With climate change, projections suggest an increasing risk of drought in Canada, particularly in the south and interior. However, there has been little research on the impacts of drought on human health and the implications of a changing climate. A review of the Canadian, U.S. and international literature relevant to the Canadian context was conducted to better define these impacts and adaptations available to protect health. Drought can impact respiratory health, mental health, illnesses related to exposure to toxins, food/water security, rates of injury and infectious diseases (including food-, water- and vector-borne diseases). A range of direct and indirect adaptation (e.g., agricultural adaptation) options exist to cope with drought. Many have already been employed by public health officials, such as communicable disease monitoring and surveillance and public education and outreach. However, gaps exist in our understanding of the impacts of short-term vs. prolonged drought on the health of Canadians, projections of drought and its characteristics at the regional level and the effectiveness of current adaptations. Further research will be critical to inform adaptation planning to reduce future drought-related risks to health.

The impacts of El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO) on winter (January–February–March) temperature variability over Canada are analysed for the period 1900–1995. Through linear regression, regional characteristics in the interannual temperature variability explained by these oscillations are firstly identified. Modulation of El Niño and La Niña winter temperature responses by various combinations of the PDO and NAO is then investigated via composite analysis. Results show the NAO as the dominant low frequency variability mode affecting winter temperature, however, the effects are mainly confined to north‐eastern regions of the country. The ENSO and PDO influences are somewhat weaker and occur over western and central Canada. It is determined that the associated winter PDO pattern has a significant modulating effect on ENSO related temperature responses. Impacts are stronger and more spatially coherent during El Niño episodes when positive PDO winters are associated with strong positive temperature anomalies over most of Canada, neutral PDO with weaker anomalies (positive in the west and negative in the east), and negative PDO with strong negative anomalies over western Canada. Analysis also suggests that La Niña and negative PDO combinations are associated with negative temperature anomalies, especially in the far west. Over eastern regions of Canada, El Niño (La Niña) events modulate the typical positive (negative) NAO temperature responses by generally making them warmer (colder). All observed relationships are explained by variations in associated mid‐tropospheric circulation over the north Pacific (i.e. Aleutian low region), and western and central North America. Results from this investigation aid in the understanding of relationships between low frequency oscillations and winter temperature variability over Canada. They also suggest the possibility of improved winter temperature forecasts based on conditions in the tropical and north Pacific, and the north Atlantic. Copyright © 2001 Royal Meteorological Society