The climate of Canada is governed by a number of elements of climate which lead to a regional variety of weather patterns in the country. These weather patterns are pertinent in determining the type of climate which each particular region experiences. Climate has many impacts on a country’s ecosystem, sociology and economy, and is therefore a key component in the overall health of any economy. Disruptions to climate can have enduring outcomes for Canada and its people. This paper attempts to discuss the current climactic patterns which occur in Canada, and outlines some ways in which climate change may impact upon the country and its ecosystems.
Canada is a vast country divided into seven climate zones all of which show regional variations in climate. The Pacific Zone is characterised by warm to cool summers and mild winters with rain falling throughout the year, reaching a maximum in the winter months. The Cordillera experiences cooler temperatures to other regions at similar latitudes because of its higher elevation . Extremes of hot, dry summers and long cold winters with low rates of precipitation are characteristic of the Prairie Zone. The Great Lakes-St. Lawrence Lowlands Zone experiences hot humid summers and short cold winters with little seasonal variation of moderate annual precipitation . The Atlantic Canada Zone is characterised by cool to warm humid summers and short, cool winters . Long, cold winters are characteristic of both the sub-Arctic and Arctic zones, and although annual precipitation is low in both zones, in the Arctic Zone annual precipitation is very low . The coldest temperatures recorded in Canada are in Yukon, the Northwest Territories and Nunavut, being as low as - 63C, which was recorded in 1947. The map above gives a general outline of Canada’s regional variations in temperature.
The Continental effect, where distance of locations from the oceans has an effect on temperature and precipitation, is very evident in the climate patterns of Canada. Mean summer and winter temperatures across Canada, vary depending of the location. In the interior and the Prairies, winters can be extremely harsh, with temperatures as low as -15C, becoming as low at -40C when taking into account the wind chill factor. Summer temperature means can range from 25C to 30C, but in the coastal area to the east and west of the county they are usually in the low 20Cs range.
Precipitation rates vary from region to region, with the highest precipitation being experienced in the Pacific Zone and Atlantic Canada Zone where up to 2500mm of rain is recorded annually. The lowest rate of precipitation is experienced in sub-Arctic and Arctic Zones, where less than 250mm is recorded annually. The high rates of precipitation on the west coast are a result of a rain shadow, where the leeward side of a mountain receives much less precipitation than the windward side. The windward slopes receive high precipitation totals due to the storms which come from the northern Pacific Ocean and dump their loads of moisture against the barrier of the Rocky Mountains. Precipitation here is also enhanced because air rises due to the presence of mountains – a process called orthographic lifting.
Figure 2. Variations in Canadian Precipitation Rates
Canada’s weather is affected by four air masses: the continental arctic, continental polar, maritime polar and maritime tropical air masses. These large bodies of air, extending hundreds or thousands of kilometres, acquire their temperature and moisture characteristics from the land or ocean conditions over which they pass . Continental air masses are generally dry whilst maritime air masses contain large amounts of water vapour which are ultimately deposited as rain or snow. The extreme conditions of Canada’s winters are caused by the continental arctic air mass which originates in the frozen north. The Beaufort Sea is ice-covered during the winter and spring and the continental polar air mass which travels over this region does not have an available source of moisture which explains the low annual precipitation rates in the areas which this air mass affects. The amount of moisture which an air mass is able to contain is related to its temperature. If an air mass is cold, it contains less moisture than it could if it was warm.
The maritime air masses, which travel over the Atlantic and Pacific Oceans, collect moisture which is later deposited when it reaches the Rockie Mountains in the west and the warm land temperatures in the east of the country, bringing with it snow, rain and fog. The map following shows the air masses which have an effect on Canadian climate.
Figure 3 Air Masses affecting Canada's Weather
The maritime tropical air mass which affects the western side of Canada originates in the Gulf of Mexico. It carries warm air from that region which results in the high temperatures and humidity experienced in eastern Canada in the summer months. In contrast, the maritime tropical air mass arising in the Pacific has brings precipitation and a mass of cooler air. When air masses meet, usually in the spring, they result in tornadoes and thunderstorms.
The third control affecting Canada’s climate is the receipt of energy from the sun. Due to the Greenhouse Effect, some of the energy received by the sun is reflected back into the atmosphere, but the remainder is absorbed by the land and the oceans. The sun’s energy is lowest at the poles and highest at the equator, which explains the difference in temperatures in these different ecosystems. This difference in energy distribution is one factor influence the presence of ocean currents as the oceans attempt to balance the differences in heat between the tropical and polar regions. This disparity in heating of the earth’s surface is the main source of atmospheric circulation, ocean currents, evaporation and precipitation which causes the weather on the earth.
Climate Change
Scientists have projected a vast range of impacts which will occur due to global warming, from an increase in road accidents to changes in whale migration. Most of these impacts are in some way related to increases in precipitation and temperature. Global warming in Arctic regions has caused changes to the weather, the physical environment, to food resources and to t Global warming will impact on cetaceans in a number of ways.
While attending the Year 2000 Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC), indigenous elders and hunters spoke about the changes they had been witnessing in the Arctic. Longer, ice-free seasons and melting permafrost were reported throughout the Arctic, together with a decline in some animal species and emergence of others. The melting of sea ice was a major concern, as was its potentially impact on marine mammals, including seals, walruses and polar bears. Since the 1980s, temperatures in the Arctic have risen rapidly, and as a consequence the behavior of whales in the region has changed. Climate change affects whales in numerous ways. The loss of sea ice reduces suitable habitats for feeding as well as areas where whales can rest and breed . Changes in prey species, and to the food webc an cause whales to lose condition and make them susceptible to pathogens. Concentrations of contaminants in their food sources, resulting from the melting of sea ice, may be lethal . Increased human habitation in this region would expose marine mammals to increased risks of boat strike and exposure to pathogens. Whale immigration routes are likely to change, allowing an intermingling of the Pacific and northern Atlantic populations, which would have disastrous consequences for biodiversity and the stability of whale populations. .
Other concerns regarding the Arctic region’s potential depletion of sea ice include the opening up of the North West passage and it subsequent environmental issues including marine pollution and oil spills. A reduction in sea ice will allow an increase in the presence of humans in the region. It may also allow access by mining companies to previously unavailable mineral resources such as oil and gas. .
Canadian residents in the north of the country have reported that the time of spring river break-up is now occurring earlier and more quickly They stated that the ice no longer breaks up, but melts away, and chunks of ice are no longer seen flowing down . Changes in the type and numbers of fish in the rivers are attributed to warmer water temperatures in summer and the melting of permafrost, which has increased river sedimentation and disrupted the ecosystem of the fish population and reproduction. .
Recent changes in the intensity and frequency of wildfires can be attributed to global warming, which has lengthened drought periods and lessened moisture and precipitation in boreal forests. Forest fires are heavily influenced by summer weather patterns and also contribute to the drying of wetlands and increased permafrost melting .
Numerous factors have an influence on the patterns of Canada’s weather. The weather is Canada is not isolated but rather is but one component in a global pattern of atmospheric circulation, ocean currents and temperature variations. Local topography and regional geography and air movement also have a part to play, but the various climatic elements influencing Canada’s climate are only one component of global patterns which influence regional climates. Any changes to these climate patterns, such as the earth is currently experiencing due to global warming, can have potentially devastating and irremediable consequences on the country as a whole, and indeed on the planet.
References
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Government of Canada. (2015, 11 10). Overview of Climate Change in Canada. Retrieved from Natural Resources Canada: http://www.nrcan.gc.ca/environment/resources/publications/impacts-adaptation/reports/assessments/2008/ch2/1032
Hambly, D. A. (2013). Projected implications of climate change for road safety in greater Vancouver, Canada. Climatic Change, 116(3-4), 613-629.
Kelly, R. C. (2013). Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years. PNAS, 10(32), 13055–13060. doi:10.1073/pnas.1305069110
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Figures
www.mapsofworld.com
http://www.theenergycollective.com/jim-baird/217791/anthropogenic-sea-level-potholes
A World of Weather: Fundamentals of Meteorology
