My last column arguing that climate change deserves a higher rank on the political agenda caused some readers to accuse me of everything from scare-mongering to misrepresenting the scientific evidence.

Critics say that computer models used to forecast global warming and its impacts are imperfect, that climate change is a consequence of entirely natural processes and that humans make only a minuscule contribution. The vehemence of the counter-arguments doesn't surprise me. Our collective denial of what's happening still runs pretty deep. Still, in the interests of discussion, they deserve a response.

First, the computer modelling. Foes of climate change theory hold that the data set is limited, the models crude and the output is therefore deeply suspect. On the other hand, computer modelling is now used for everything for predicting capital market flows to simulating atomic explosions for the Pentagon. Indeed, climate computer modelling is only in question, it seems, when it suggests that curbing our profligate greenhouse gas production might be prudent -- a decision which would exact economic cost.

So let's be clear. It's not the value of computer modelling that's really at issue, it's that the models imply the necessity of decisions that carry a price -- whether in foregone revenue or consumer inconvenience -- which some of us refuse to accept.

The Inter-governmental Panel on Climate Change, comprised of hundreds of leading scientists, concludes, however, that as computer modelling improves, forecasts about global warming become more convincing than ever.

Second: global warming is a consequence of natural events. The case is made that oscillations in planetary climate are not new and what's happening now is merely the latest, perhaps related to fluctuations in the sun's output of energy.

Nobody involved in global warming research questions the geological record regarding the waxing and waning of climatic regimes which have seen both warm seas at the poles and most of North America deep-frozen under two kilometres of glacial ice.

The point is whether human activity has contributed to this global warming trend by loading the atmosphere with greenhouses gases. If it has, could this contribution be accelerating the process of warming at a rate which might have profound repercussions for the global ecosystems, upon which civilization relies, over the coming century?

According to the climate panel, the consensus of mainstream science is now that we are indisputably playing a role in contributing to global warming, it is already affecting how we live and promises even greater impacts in the near future. "The balance of evidence suggests a discernible human influence on global climate," the panel's technical report says.

For those who prefer details, the whole study is posted on the panel's website. Reading it makes for a sobering experience.

"Most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations," it says. And points out that even if some miracle of world cooperation froze the emission of greenhouse gases at today's level, the effects would still be felt for at least a century and probably longer.

Third, critics claim the effect of the human contribution to global warming is small. Everything, of course is relative. It depends how one chooses to interpret "small."

Here's what the highly respected journal New Scientist said in its lead editorial for December 15, based in part on the emerging international consensus: "The spectre of catastrophic climate change is forcing nations around the world to question how they make their energy. With carbon dioxide pushing up the global temperature, most governments agree they must move away from the Victorian technologies of burning coal and oil towards cleaner options."

New Scientist details the recently leaked review of national energy security and supply by the British government, which proposes dismantling that country's nuclear and coal-based industries. It points to the need to swiftly shift the U.K. away from fossil fuels and toward a renewable energy program which combines wind, tidal and biomass technology with energy conservation initiatives.

The penny, it seems, has just dropped in Europe. If the proposals seem radical, they are conservative by comparison to the consequences of accelerated global warming.

The Inter-governmental Panel on Climate Change concludes it is now "very likely" the world will see the melting of a "substantial fraction" of the planet's total glacier mass. "The present Antarctic and Greenland ice sheets contain enough water to raise sea level almost 70 metres if they were to melt, so that only a small fractional change in their volume would have a significant effect," it warns.

At the same time, increased temperature will increase evaporation rates over the oceans triggering both more powerful and more frequent hurricanes and typhoons and more intense precipitation events.

But these changes in extreme weather patterns promise increased drought over most mid-latitude continental areas with the worst effects felt in already dry regions like southern Alberta and southwest Saskatchewan. Ironically, Alberta is among those provinces most resistant to curbs on greenhouse gas emissions precisely because it is already one of Canada's worst polluters.

So there we have it. The Inter-governmental Panel on Climate Change says the computer models are reliable and human contributions to global warming are significant. U.S. National Academy of Sciences warns that greenhouse gases and other atmospheric pollutants could trigger vast, abrupt and possibly disastrous climate changes. The British government is contemplating massive shifts toward renewable energy sources as the way of the future.

Yet here in B.C., our Liberal government plans to reduce regulation in order to boost fossil fuel production, to build big new fossil fuel-fired electrical plants, to reduce taxes on over-sized, over-powered gas-guzzling motor vehicles and to continue to dismantle a wide range of environmental protections under the guise of "streamlining" administration.

As I say, the denial runs deepest where the coming realities of climate change impose a demand for hard and intelligent decisions upon those who prefer political expedience and the temporary comfort of an increasingly untenable and illusory status quo.

shume@islandnet.com