Greenpeace spokeswoman Susannah Bailey's attack on branches of the New Zealand business sector, which she accuses of continuing to plead grey on global warming, misses the key point.

Political action on climate change is not a game to be played and won or lost, and Greenpeace does us a disservice by encouraging that view. Little does the public realise the debate over climate change usually conflates issues of science and politics.

The robustness or otherwise of the science underpinning the role of greenhouse gases in the atmosphere is the key to assessing the risk from human induced climate change issue. But seldom if ever are the uncertainties of the science discussed.

Seldom if ever is the question asked: Where is the evidence for catastrophic climate change from human action?

Rather than search for the evidence, groups like Greenpeace defer to authorities, such as the Intergovernmental Panel on Climate Change (IPCC), a political entity which appears to have a monopoly on wisdom in global warming matters.

Rather than debate the issues, they attack those who disagree, using defamatory labels. Yet the opposite of scepticism is gullibility.

The fanatical name calling and personal attacks expose the strong ideological elements that drive global warming alarmist thinking. It's as if the depth of passion is overcompensation for doubt and uncertainty.

Why else would environmentalists squander so much effort trying to discredit individuals and organisations who disagree?

Few scientists are willing to put their head above the parapet, for a variety of reasons, not the least of which is that, to paraphrase Voltaire, it is dangerous to be right when the authorities are wrong.

Moreover, vote counting is a risky way to discover scientific truth. Scientific validity is not determined by a show of hands. Pronouncements from Greenpeace or the IPCC do not and cannot change the facts. No one doubts humans affect climate. The debate is whether the effects are "dangerous".

There is no hard evidence that increases in carbon dioxide in the atmosphere put there by human activities are causing or will cause dangerous change to global climate.

The Earth's surface has warmed slightly over the last 150 years, but research shows that floods, droughts, hurricanes and tornadoes have not increased in frequency.

The climate facts are well established and well recorded, but often ignored when it comes to global warming catastrophism: