There is no such thing as "irreversible" climate change. The climate will eventually, in some form or degree, continue to change . . . and change repeatedly . . . regardless of whether the human species is here or not.

Australian net greenhouse gas emissions can be zero by 2020 - an outline of how it can be done is at http://cscoxk.wordpress.com/2008/04/09/a-market-approach-to-reducing-global-emissions/

See also a discussion of the general principle of the approach at http://www.onlineopinion.com.au/view.asp?article=7085

Emissions permits or carbon trading will not work effectively or quickly enough to make a difference. The reasons are as outlined in this article by James Hanson. Make the price of energy of fossil fuel high and it encourages producers to burn more not less.

The ONLY solution is to direct investment in clean energy technologies and we can direct investment efficiently and equitably through market mechanisms as shown in the references above and at http://rewards.edentiti.com

In the long term green energy is economically advantageous because the running cost of solar thermal and geothermal is half the running cost of burning hydrocarbons. We can do it and we can start immediately and not wait for international agreements nor wait for emissions permits systems to be designed.

We have the technology and space today to produce solar thermal and geothermal clean energy for low running costs. All that is lacking is the political will to do it.

Sonofeire, I agree. The world continues, despite humanity.

Whilst claims to irreversibility might suit the childish and emotionally driven arguments of the meddlers and proponents of "Socialism by Stealth", they have no consequence to the earth and quite honestly barely any consequence to the rest of us.

Children, of any age, will always prattle on about the boogey man, the current boogey man is simply the thing they cannot control and feel compelled to make the earth their personal property, which, of course it is not. The earth is the property of all who live here and hopefully the adults will always outnumber the children.

Speaking of which, the one thing we could do to improve the environment is to have fewer children following in our footstep.

Debate on population control and its reduction would be far more productive than all this other childish prattle.

"Irreversible" refers to the point at which changes to the climate are self-compounding and cannot be altered within anyone's lifetime or forseeable future. You willingly missed the point here Sonofeire. Cyclical changes to the climate do occur, though none have been as sudden as that which is happening now nor has it affected civilisation to the degree it is anticipated. Who knows?

There is plenty of evidence we may witness the disappearance of the arctic soon enough. But, I prattle.

The argument is confused. Although high fuel prices are a pain in the short term; they encourage conservation and substitution. If petrol prices are high, more cars are converted to using LNG and so on. As US petrol rpice should be much higher than they are (Government taxes are a big part of prices in Aus, but are lower in the US which encourages waste), he has considerably hide in complaining about those prices.

Higher prices also encourage extraction from oil sands and exploration for more oil, or oil sands, although I don't think that's what the author really wants to hear.

As for the business about supply restrictions, I haven't looked at oil for some time but I do know the stuff about coal is nonsense. the reason no one has tried to estimate coal reserves for some time is that there is still obviously too much of it for the exercise to be worth the trouble. Australia is the world's largest coal exporter, and I've never heard of anyone even try to suggest that we are going to be running out any time soon.

Hansen means well but his arguments should be ignored.

Dear oh dear. The horse James is flogging sadly died long ago. Current oil prices are a product of chronic under investment during the period of low prices not a shortage of oil. There is, on current estimates, at least 50 years supply or about 4500 billion barrels of oil in known reserves and all oil producing countries are now investing in exploration and oil field development. This is in addition to exploration in countries not currently producing oil. It appears that James, now rapidly losing any credibility in the global warming debate as the evidence continues to stack up against him, is looking for something else to frighten us with.