Canada is an energy superpower on a warming planet.

Industrial and human activities, from producing cement to burning gasoline in cars and generating electric power from natural gas and coal, have caused excess heat-trapping gases like carbon dioxide and methane to be emitted into the atmosphere. According to the Intergovernmental Panel on Climate Change, (IPCC, a UN scientific body that won the 2007 Nobel Peace Prize along with former U.S. Vice President Al Gore) there is 35 % more carbon dioxide in our atmosphere now than there was before industrial times. Scientists have also observed an average increase in world temperatures of at least 0.55 of a degree centigrade in the past thirty years. The IPCC has concluded that most of that temperature increase is “very likely due” to the increase in greenhouse gas concentrations.

Although half a degree centigrade does not sound like much, there is substantial evidence that climate change is already affecting natural systems. Permafrost is becoming less stable, polar ice is melting, oceans and lakes are becoming warmer, glaciers are melting faster, birds are laying their eggs earlier each spring and plant and animal species are expanding their ranges toward the north and south poles. Many scientists say that the greenhouse effect is responsible for the recent spate of warm winters in British Columbia that have allowed the pine beetle to thrive, wiping out much of the province’s pine forests. Worse is yet to come. Environment Canada warns that the “speed and magnitude” of the temperature increases are “expected to cause severe storm patterns, more heat waves, changes in precipitation and wind patterns, a rise in sea level and regional droughts and flooding.”

Although there is general agreement on the overall direction of climate change, scientists still quibble over how profound or immediate these effects will be, just as economists argue about the costs of action—or inaction—to mitigate climate change effects. Some scientists warn that we are approaching a so-called “tipping point,” or a point of no return, where climate change will spiral beyond our ability to reverse its effects. Where that tipping point is exactly is unclear. Some experts suggest that beyond “a threshold of 2°C the risk of large-scale human development setbacks and irreversible ecological catastrophes will increase sharply.”

Next section: What has been done so far?