When 259 authors from 39 countries examine hundreds of scientific papers and arrive at a consensus, perhaps it's worth listening.
But in Canada, at any rate, about 30 per cent of the population remains convinced that climate change isn't happening – or, if it is, that it's caused by natural events, sunspots or just about anything other than human activity, notably burning fossil fuels.
So it was entirely predictable that the critics and skeptics of climate change went into overdrive when the fifth report of the United Nations Intergovernmental Panel on Climate Change reported last week that warming is an "unequivocal" fact, that the "observed changes are unprecedented over decades," that oceans and atmosphere have warmed, snow and ice have diminished and sea levels have risen.
Scientists, if they're any good, are always updating their data. If they are honest, they adjust conclusions according to new observations. So this IPCC group, which is accused by critics of being rigid ideologues, actually observed new data and said forthrightly that the rate of warming increase had slowed in the last 15 years compared to the two previous 15-year periods.
This finding does not rebut the long-term trend of warming; it merely adjusts the pace of the warming, at least temporarily, because 15 years in the context of a century or two is something temporary.
It takes a while to read the whole IPCC report, as opposed to just the headlines about it – to say nothing of commenting, as some observers rushed to do, even before the report had been released.
Read in its entirety (not easy for the non-scientist), the report is remarkably hedged. When the scientists are almost sure, they say "virtually certain." When they are somewhat less sure, they say so. That is more than can be said for the critics, who are sure all the time about everything, to say nothing of the really intellectually dishonest among them who admit grudgingly that climate change is man-made but then scoff at everything recommended or attempted to combat it.
In typical fashion, Canada's federal government greeted the IPCC report without making a minister available for comment, instead issuing a three-paragraph press release praising itself and offering partisan, ad hominem attacks against other political parties.
Prime Minister Stephen Harper's government has at its core a disproportionate number of that 30 per cent of deniers and skeptics. If you govern for your base, you can't ignore these people. They are locked in opposition to action, have their own journalists and climate-change scientists who deny the reality of human-induced warming, and therefore live in an intellectual universe quite separate from the majority view of reality in the rest of Canada and the Western world.
Even if the government's own websites acknowledge the reality of human-induced warming, and even stress the future dangers it portends, no government dependent on how its base views climate change can be seen expending much political capital on the issue.
As a result, while promoting the expansion and transport of bitumen oil at every opportunity, the Environment Minister says as little as possible, the Prime Minister never talks about the issue, the government does a whole bunch of ineffectual things – investments in carbon capture and storage, tax credits for transit passes, subsidies for ethanol, regulations on coal-fired plants that don't take effect for a long time – while hesitating to do anything that might be seriously effective.
In other words, the government's heart really isn't in the file, because it has so many people who think climate change doesn't exist or has been manipulated by all those scientists from all those countries over all those decades who have written all those hundreds of studies in a vast attempt to mislead the world.
The scientists, with all their hedging, remind us that solar irradiance and cosmic rays don't cause warming. The rate of carbon buildup over the past century is unprecedented and caused by the burning of fossil fuels. The Arctic, they say, "will warm more rapidly than other global areas."
They state: "Limiting climate change will require substantial and sustained reductions in greenhouse gas emissions." Instead, the world is headed in the opposite direction.