Worksheet 1.1 Answers
Climate change in Canada

1. The IPCC's position is that human activity since 1750 has played a significant role in overloading the atmosphere with carbon dioxide (CO₂).
2. The chart illustrates an increasing trend in mean temperature over time. If annual mean temperature was plotted against the base period from 1881 to 1910, the magnitude of the trend would be greater.
3. One of the greatest concerns associated with climate change is the anticipated increase in the frequency of extreme weather events.
4. Other changes are more gradual. Lakes and rivers generally freeze later and thaw earlier than they used to, resulting in difficulties building and maintaining ice roads. The frequency of very cold winter temperatures in some regions decreases. This results in increases of some pest species, like the mountain pine beetle, that would typically be killed off by these cold winters. (Other examples are possible.)
5. Though Canada has only 0.5% of the world's population, it contributes 2% of greenhouse gases because of the large size of the country, the low density of its population, its high energy demands due to climate, its resource-based economy and the volume of goods it exports.
6. The greenhouse effect is a heat-trapping process that occurs naturally in the atmosphere. Without it, the earth's average temperature would be -19^oC instead of 14^oC. Incoming energy from the sun penetrates the atmosphere to warm the earth. The planet then radiates heat back out toward space. Some of the outgoing heat is absorbed by greenhouse gases in the atmosphere and re-emitted back to the earth, keeping the planet warm.
7. Climate is the average weather that a region experiences. It encompasses all aspects of weather and is a guide for the kind of weather to expect. While weather can vary dramatically from one day to the next, climate cannot.
   
   Climate change is the long-term change in average weather patterns and can be caused by both natural processes and human activities. Examples of natural factors are changes in solar output and volcanic ash.
   
   Global warming is an increase in average global surface temperature.
   
   Greenhouse gases (GHGs) are gases released into the atmosphere that contribute to the greenhouse effect. Some are made by both human and natural processes, while others are entirely human-made. Examples of a human-made source of GHGs are the combustion of fossil fuels by driving cars or producing electricity. GHGs include carbon dioxide, methane, nitrous oxide, sulphur hexafluoride, hydrofluorocarbons, perfluorocarbons.
8. Methane has 21 times the global warming potential of carbon dioxide.
   
   The relative impact of methane compared to carbon dioxide would depend on its proportion of the total greenhouse gases in the atmosphere. (To be seen in the next worksheet.)