Canada predicts two degrees of warming by 2050
Environment Canada’s most optimistic projections for climate change predict even faster warming of the atmosphere than the consensus view reached this week by an international panel assessing the latest scientific evidence.
Senior Environment Canada scientist Greg Flato said that even in the best-case scenarios for limiting growth of heat-trapping greenhouse gas emissions, his federal department’s computer models show average global warming of about two degrees Celsius above pre-industrial levels by 2050.
In a report released Friday, the Intergovernmental Panel of Climate Change (IPCC) said it’s likely that temperatures will exceed this two-degree-Celsius threshold by 2100, though not necessarily by 2050. But it anticipates some scenarios in which warming from 2081 to 2100 could be as little as 0.3 degrees, relative to the 1986 to 2005 average temperatures, or as high as a maximum of 4.8 degrees above the temperatures of the 1986 to 2005 period by 2100.
Governments from around the world have agreed that the two-degree threshold is a dangerous tipping point for the atmosphere. At that level, climate change would threaten to disrupt ecosystems and accelerate the rise in sea levels and melting of ice in the Arctic; it would also increase the likelihood of extreme weather events, such as longer and more frequent heat waves, as well as heavier rainfall in some areas, and droughts in others.
The governments have agreed to slash greenhouse gas emissions to avoid this tipping point as part of an international commitment made by world leaders, including Prime Minister Stephen Harper, at a 2009 summit in Copenhagen, Denmark.
While Flato said there were different projections about the impacts of carbon emissions in the atmosphere, he also praised the IPCC process, noting that its mandate was to take a collection of different scientific research and reach a consensus.
“Our (Environment Canada) model, in isolation, produces results that are in roughly the two-degree warming range in the midcentury,” he said. The department’s computer-modelling centre is world-class, he said. “But if you look at all the models together, which is the important thing to do, there is a range and that range is important.”
Flato also noted that the IPCC report demonstrates progress in research identifying the links between specific levels of carbon emissions from human activity and the resulting temperature levels. This could provide governments with information to help them decide how much fossil fuel, such as oil or coal, should be left in the ground and what will happen to temperatures if the energy is consumed.