John Roughan: Coalition of the willing missing from equation

The last time I saw Don Brash he recommended a book he had found fairly convincing on the subject of climate change. That was months ago, well before the summer gave way to the coldest Auckland winter I can remember.

I mention it now because global warming seems a good subject in this weather, and because the Green Party, which says it is coming out of the red corner of politics at last, demonstrated its new spirit this week with four votes to save farm dogs from microchips.

The Greens say they are ready to deal with whichever party wins the next election, though National still presents a problem for them. They say "it is led by a climate-change denier".

Sceptic maybe; it is possible to remain a climate-change sceptic after reading the book that made an impact on many last summer, The Weather Makers by Tim Flannery, but not be in outright denial.

Flannery, an Australian biologist, is best known for an earlier book, The Future Eaters, which memorably explained, among other things, why Australia's bush needs to catch fire from time to time and how human settlement has made fires worse, for humans and the bush.

He is a matter-of-fact interpreter of science for the uninitiated and a late-comer to climate change research. "I was busy with other things, and I wanted to wait and see, hoping an issue so big would sort itself out."

My climate-change scepticism, before reading his book, was quite the opposite. A rise in the world's average temperature by a degree or so over a decade didn't seem so big at all.

An extra three degrees, later upgraded to five degrees, over half a century sounded manageable, and even welcome in temperate climates such as this.

Receding glaciers and melting polar ice might necessitate migration from low-lying cities and Pacific atolls, but there would be plenty of warning and it seemed more sensible to move some people than try to move the developed world to a low-carbon diet.

But Flannery explains that a five- degree rise in global temperature is a big proposition. He says the last time the world experienced a change of that magnitude was about 10,000 years ago and it took all of the 10,000 years before to climb so far. That was the fastest five-degree rise previously recorded and it took 10 millenniums.

The global temperature rise predicted for the next 50 years is comparable to the greatest climate shifts that have occurred from greenhouse gases, sunspots and variations in Earth's orbit, causing life to adapt, migrate and sometimes suffer extinctions.

The fossil record shows the shifts to be usually sudden rather than gradual, after long periods of climatic stability.

The last major cataclysm was 54 million years ago when the dinosaurs and all other sizeable life forms died out, possibly from an asteroid collision which could have released enough material into the atmosphere to cause climate change. That ended an era when the planet was much warmer than it has been since.

The sliver of time since human life appeared, a mere 150,000 years, has been a relative ice age, containing periods of warming, the last of which has lasted 8000 years and we are still in it. We date civilisation from the beginning of that warming phase.

So five degrees is a big deal. But it is still a projection based mainly on computer simulations of what will happen if we stay on course to double the carbon dioxide in the atmosphere.

The computer models have operated for a couple of decades so their early predictions can be checked against actual temperature changes at stations set up around the globe.

The credibility of the computers seems to be almost universally accepted. Even the world's foremost sceptic, Danish statistician Bjorn Lomborg, does not dispute the scale of climate change and that it is caused by carbon dioxide emissions.

His contention is simply that there is not much we can do about them, and that for the cost of imposing Kyoto controls, the world could bring greater and more immediate benefits to the Third World.

Greater than the survival of civilisation? The stakes are nothing less, says Flannery. "We have known for some decades that the climate change we are creating for the 21st century was of a similar magnitude to that seen at the end of the last ice age but it was occurring 30 times faster ...

"We have known that agriculture was impossible before the long summer of 10,000 years ago. We have seen that human health, water and food security are now under threat from the modest amount of climate change that has occurred. If humans pursue a business-as-usual course for the first half of this century I believe the collapse of civilisation due to climate change becomes inevitable."

The trouble with climate science is that in our bones we cannot believe the extraordinary warnings it is giving. If we did the world would be acting.

Flannery cites the success of the campaign to stop ozone depletion when that became evident in the 1970s. But he misses the point that when the evidence is convincing, the world acts.

When the ozone hole and rising incidence of skin cancer were discovered, developed countries quickly got together and banned chlorofluorocarbons. There was no dickering with Kyoto-type targets and taxes and worrying about whether all emitters were on board. China never reduced CFCs and is still using them. But who cares now? The ozone is showing definite signs of repair.

Carbon emissions could just as quickly be reduced by a similar coalition of the willing. It isn't happening because at heart most people are not moved by the alarm.

Deep down we are still climate-change sceptics and the reason, I think, is the scale of it. Deep down we still believe the forces of nature are much bigger than us and ultimately self-correcting. Deep down we are probably right.