xoddam, the proposition I put was that there is no basis for the carbon credit schemes, because there is no significant global warming.

There is no basis for believing that carbon emissions, from human activity, have any effect on global warming even if there was appreciable warming.

There has been no warming in the southern hemisphere since 1979.

It is now established that the hottest year in the US was 1934,

If there is warming somewhere else on the globe, it is local not global, which is why the whole concept of "global" is now questionable.

When it was raised that the Medieval warm period was warmer than any current warming, and that this was a most prosperous period, the alarmists argued that it was only local warming.

We only have local warming now, but the same people argue that it is global. Hardly straight thinking.

Dr. Wang, who supplied figures for China, has now confessed to fraud in his figures, so do not expect any warming in China.

You lost the plot somewhere early in the piece, and now have moved even further away from the topic.

Nick,

what you said was "the problem of climate change, is the problem of undoing the harm done by the nonsense of the alarmists."

I have asked you to justify the claim that harm has been caused, and your imputation ("a further burden on our overtaxed citizens") that acting to reduce greenhouse emissions will be excessively costly.

Bald assertion of historical local temperature extremes doesn't prove that the Earth is not warming up, any more than bald assertion of recent local temperature extremes (though someone's "favourite scientist" often did so) proves it is.

But the physics of the earth's radiation balance are not in dispute. As greenhouse gases are added to the atmosphere, temperatures will rise -- lagging emissions by some years. Moreover, as temperatures rise, "natural" causes can be expected to add to the greenhouse gases in the atmosphere in a positive feedback, causing potentially catastrophic abrupt changes in climate across the globe.

Bob Carter has not demonstrated that the physics is wrong, or that the globe is as likely to cool as it is to warm. Nor have you.

But I didn't ask you to do that. I accept that you don't believe it. You probably also don't believe in the Flying Spaghetti Monster; that's your issue, not mine.

What I have asked you to do is to demonstrate why you think taking steps to reduce greenhouse emissions would be harmful, when the primary economic consequence of energy efficiency and renewable energy supplies is to save and/or delay other escalating costs.

I repeat my challenge. Explain your concern.

Thankyou xoddam! You've saved me from having to write a lengthy reply. Maybe tomorrow when I've had more time to think about it. In the meantime...

Nick, I think it's healthy to be a skeptic but to totally deny even the possibility of global warming seems more like 'head in the sand', given that research is ongoing and at least some of the most recent evidence seems to be confirming the predicted warming trend.

It's the nature of research that some other scientist (or skeptic) will always pick holes in it, but the true scientist will maintain an open mind (at least until the evidence either way is totally overwhelming). It doesn't automatically follow that the rest of society should sit around fiddling while we wait for scientific certainty - by then our options could be severely reduced. Why not act now while we have a range of options to choose from?

I'm not suggesting we should turn our economy on its head overnight - but we do need to start looking seriously at alternatives to our current dependence on fossil fuels. Given that oil is about to hit $US100/barrel, I'd much rather see my transport dollars go towards a fuel source that is less politically volatile, less likely to run out and less likely to cause irreversible damage to our atmosphere.

Nick,
You seem determined to refute any claims for evidence of “global warming”, despite an overwhelming body of scientific research which increasingly confirms a significant warming trend over the past century or so. What are your references to substantiate your claim that “there has been no warming in the southern hemisphere since 1979”? Is this based on current or outdated scientific evidence? And even if true, is this irrefutable proof that the documented warming trend on the Australian continent is simply a local or regional aberration?

The U.K.’s Royal Society this year refuted a number of misleading climate change arguments in ‘Climate Change Controversies: A Simple Guide’. Have you read it?
http://www.royalsoc.ac.uk/page.asp?id=6229

Although the IPCC, Royal Society and similar scientific fellowships are not beyond criticism, the fact that these bodies are largely in agreement on the general premise of human-induced global warming must carry some weight in decision-making processes.

At the risk of repeating myself, policies and actions should not be based on any one scientific study which may or may not confirm previous scientific studies. Nor should it be based on the pronouncements of any particular alarmist or the denials of any particular skeptic (such as yourself).

In the real world, decision-makers have to weigh up environmental, social and economic factors based on the best available information and assessments of risk. Unfortunately, short-term political imperatives tend to dominate over reasoned decision-making (as seen in the current Federal election campaign), so it is up to individuals to hold politicians and bureaucrats to account to ensure they act with intelligence and integrity, especially when it is our future at stake.

I too challenge you to produce evidence of significant overall harm likely to result from action to reduce our greenhouse gas emissions.

First you might like to listen to a podcast from this morning’s Radio National program ‘Life Matters’ which discusses a new sustainable paradigm for the future of the planet:
http://www.abc.net.au/rn/lifematters/stories/2007/2062104.htm