In recent years, climate change has become one of the most important issues on the planet. Climate change is a change in the 'average weather', affecting all the features we associate with weather, including temperature, wind patterns, precipitation, and storms.

Myth : A cool summer or colder than average winter means that global warming is not really a problem.

The average temperature at the Earth's surface is 15°C because of a natural phenomenon called the 'greenhouse effect'. If it were not for certain gases that function as a greenhouse to trap the sun's heat close to the Earth, the average temperature would drop to -18°C, and life as we know it could not exist.

Since the beginning of the Industrial Revolution, this natural effect has been enhanced by human activity (use of fossil fuels, agriculture, deforestation). This enhancement of the greenhouse effect contributes to global warming and may have various environmental repercussions.

(Environment Canada, 1993)

In addition to water vapour (H₂O), the main greenhouse gases are carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Methane and N₂O have a greater capacity to absorb heat than CO₂ and are therefore more powerful greenhouse gases. However, CO₂ has the greatest impact because it is the most abundant. Since the Industrial Revolution began, concentrations of methane (CH₄) have risen by 145%, whereas those of carbon dioxide (CO₂) and nitrous oxide (N₂O) have increased by 30% and 15%, respectively.

Scientists anticipate that in 40 to 60 years, the quantity of CO₂ in the atmosphere will be double that of the pre-industrial era. They also consider that this dramatic increase in the concentration of CO₂ and other greenhouse gases will have an impact on climate.

Numbers are in billions of tonnes of carbon transferred annually or stored.

Did you know?
Weather and climate are not the same thing. Climate = average weather over at least 20 to 30 years. When describing climate change, it is important to distinguish between long-term and short-term changes.

How can we reduce the amount of carbon in the atmosphere?

Did you know?
Even if emissions of greenhouse gases were to stop immediately, earlier emissions would continue to affect climate for centuries to come.