Dr. James E. Hansen apparently knew nothing about the July 1, 2008, carbon tax imposed on British Columbians. But he has something to say on the subject.

Hansen is a scientist with notable credentials. As Director of NASA's Goddard Institute for Space Studies, he is one of the world's foremost climatologists and, in a June 23, 1988, presentation to the US government, was the first to warn that extreme weather anomalies were "almost certainly due to greenhouse gases" being emitted by human activity. On another June 23, exactly 20 years later, Hansen was giving an update to a House Select Committee. His words, offered as a private citizen, are worth careful consideration for anyone doubting the importance of carbon taxes.

"Now, as then," said Hansen, " I can assert that these conclusions regarding [human induced climate change] have a certainty exceeding 99 percent... [and] that global warming [has] enhanced both extremes of the water cycle, meaning stronger droughts and forest fires, on the one hand, but also heavier rains and floods." These weather extremes are now fully supported by evidence, and global warming is now the "consensus" of the scientific community. While "international recognition of global warming was swift," Hansen notes, our corrective actions have "faltered".

This faltering is mostly due to political inaction – a nearly imperceptible rise in average global temperature of less than 1° C hasn't caused alarm. But, beyond the rising incidence of extreme weather anomalies, "more warming is already 'in the pipeline'," Hansen says, "delayed only by the great inertia of the world ocean. And climate is nearing dangerous tipping points. Elements of a 'perfect storm', a global cataclysm, are assembled."

Hansen notes in his presentation that the Arctic Ocean is already beyond its tipping point and will soon be ice-free in summers. The melting of the West Antarctic and Greenland ice sheets may soon be "unstoppable". He expects a 2 metre rise in sea levels by the end of this century. Among the results: "hundreds of millions of people would become refugees" and countries would have "no stable shoreline".

Climate change would also result in "mass extinctions" of species and "ecosystem collapse". Recovery from this biodiversity disaster would take hundreds of thousands of years.

"The safe level of atmospheric carbon dioxide," Hansen warns, "is not more than 350 ppm (parts per million) and it may be less. Carbon dioxide is already 385 ppm and rising about 2 ppm per year." And paleoclimate data confirms that "the oft stated goal to keep global warming less than two degrees Celsius is a recipe for global disaster, not salvation."

Salvation – if it is not already too late – means a radical reduction in carbon dioxide emissions. All coal, Hansen suggests, must be phased out of use, unless its CO2 is permanently sequestered. Since vehicles burning gasoline and diesel make carbon capture difficult, he proposes no further development of oil reserves or other fossil fuels. "Those last drops are no solution. They yield continued exorbitant profits for a short-sighted self-serving industry, but no alleviation of our addiction or [a] long term energy source." We should use the oil supply crisis as an incentive to move promptly "to a carbon-free energy".

"Special interests," he contends, "have blocked transition to our renewable energy future" and "fossil fuel companies choose to spread doubt about global warming, [just] as tobacco companies discredited the smoking-cancer link." The CEOs of these fossil energy companies," he charges, "should be tried for high crimes against humanity and nature."

Interestingly, Hansen's proposal to reduce CO2 emissions closely matches the carbon tax being imposed in British Columbia. (In a July 1, 2008, interview on CBC Radio 1, he indicated that he was unaware of this development in BC.) He doesn't seem to support a cap-and-trade system presumably because it is too indirect and cumbersome. As for the carbon tax, he says, "The entire amount must be returned to the public, an equal amount to each adult, a half-share to children."

This money, he proposes, would arrive as direct deposits to each person's bank account so everyone would have tangible, monthly evidence that these taxes were being applied, and could then choose the smartest strategy for using products and energy. "Profligate energy users will have to pay for their excesses." But almost immediately, he believes, "Demand for low-carbon high-efficiency products will spur innovation... And carbon emissions will plummet as energy efficiency and renewable energies grow rapidly." Hansen proposes that these measures should be coupled with direct-current, high-voltage buried transmissions lines to efficiently distribute energy, and with stringent standards on building codes and vehicle fuel consumption. By his estimate, we have two years to begin this radical renovation.

In the United States, the "brontosaurian" Bush administration is in its last months and the air is electric with the possibility of new opportunity and direction. In Canada, a dithering and muddling federal government is being shamed and dragged toward greener emission policies. But the real change that is taking place in both countries is in forward thinking provinces and communities.

A significant force behind all this change is the voice of Dr. James E. Hansen. And 20 years later, he's still here to remind us – in case we've forgotten – that we have serious work to do. And a carbon tax is far, far better than the alternative.