What is Climate Change?

Climate change is a long-term shift in atmospheric conditions occurring worldwide. For thousands of years, the Earth's climate has remained relatively stable. Temperatures, rainfall, the length of the seasons, and other environmental factors have sustained humans, animals and plants. This stability has existed thanks, in part, to the greenhouse effect.

Just as the glass of a greenhouse keeps the sun's warmth inside, a blanket of greenhouse gases traps solar heat in the planet's atmosphere. Without these gases ─ mainly water vapour, carbon dioxide, nitrous oxide and methane ─ the heat of the sun would escape into space, and the average temperature on Earth would plunge from 15 to -18 C.

However, the substantial increase in greenhouse gases produced by human activites in the last 100 years has enhanced the natural process and provided an accelerated change in climate.