If climate patterns are uncertain so are the social costs, hence it may be better to err on the side of caution in case they turn out to be catastrophic. If we underreact now it may be a harsh legacy on future generations. After all it is humans of the past hundred years who burned most of the fossil carbon built up over half a billion years. Some are saying that all fossil fuels (in order oil, gas and coal) will be in severe practical shortage within twenty years. That might limit warming but can low carbon technology or willing cutbacks possibly make up the energy gap? Moreover there is barely enough water to go around on an affordable basis. Therefore I think we should try hard to create a smooth transition to a likely difficult future. If we did fluke some technical breakthroughs we haven't lost much; if it turns out badly then we may have something to fall back on.

Postscript to those who say Sydney's cool summer disproves GW; try averaging temps with Adelaide.

Another thing the environment alarmists need to think about, as they toss and analyse their monkey bones and chicken gizzards, is the result of their hugely expensive must-have emission cuts to the consumers.

Can they judge the effects on society of these costs? Will they be prepared for the turmoil, anarchy and violence resulting from lack of reasonably priced services and food? What if the expensive restrictions make no difference to climate change?

There is so much missing from this article "Future Carbon" that it is quite seriously misleading. I am amazed, given the author's CV and qualifications. Where is there any reference to the observed sharp increase in carbon PPM in the atmosphere and observed increases in average world temperatures and temperature trends across major populated and foodgrowing regions?This is not risk forecasting: it is recording of measured scientific data. Yes, it does not prove a correlation - but it is pretty strong inductive evidence of one.

Secondly, there is no mention of the inevitability of exhaustion of non-renewable energy sources - carbon-content fossil fuels. There is no such thing as 'future carbon'. Any transfomation of CO2 gas to recapture burnable carbon will involves a net energy cost - by the iron laws of thermodynamics.

So what if gas-fuelled electricity generation is more "efficient" at present price relativities than wind-power generation. What good will that do us, when gas prices escalate as gas becomes more scarce and costly to access?

The embedded assumption in this essay is that there is no such thing as energy resource scarcity or exhaustion - that technology, human ingenuity, will always find ways to use oil or gas or coal or biofuels more efficiently. But that is irrelevant now. We know that all those resources are subject to predictable exhaustion within a few human generations - even biofuels, in terms of water and soil fertility exhaustion.

What good is increased electronics efficiency if the market simply takes the benefit in the form of larger and larger televisions and home entertainment centres, resulting in continued increases in usage of fossil-fuel based electricity? We are cooking the planet while we pat ourselves on the back for for our increased technical efficiencies. The answer is we need both - greater efficiency in energy production and application, and greater economy in energy consumption. It is the second part that is harder to pull off.

We need to use price signals to move economies to reliance on renewable energy sourcing. That is Garnaut's task.

I hope Garnaut reads this.

Garnaut hasn't even factored in existing innovations let alone new ones. The increase in the price of oil and coal has already induced a response by the Chinese government. There are 86 new nuclear power plants set down for the 2011-2015 five year plan alone (one every 3 weeks). There are none set down, yet, for the 2016-2020 plan because these new, mass produced plants only take three years to build from scratch.

Garnaut has excluded all of this from his interim report (giving us weasel words instead) because his preposterous call for 90% reductions could only be rationalised on the basis of his silly assertion that things were a lot worse than they seemed.

In fact, the IPCC's moronic A1F1 scarenario, that Garnaut has relied upon, has been blown clean out of the water already, without a single new innovation. The faster than projected growth in China merely brings forward the point in time when developed status is reached and emissions growth plateaus. For Garnaut to fail to grasp this simple economic fundamental is inexcusable, but par for a labor party hack.

Instead, the A1F1 projection zooms off into an imaginary stratosphere with not even a 1% annual emission dividend while Garnaut's professional credibility takes a dive of commensurate proportions.

Any search on the peer reviewed literature will quickly show two things: one the IPCC report is perhaps the most optimistiuc view of the impact of climate change. Two there is consensus about the reality of man made global warming - the debate centres around on which models are the most adequate representation of the future. The prudent policy course is to assume the worst. The other reality is that what Australia does is largely irrelevant. But we will experience the effects nonetheless so again it is prudent to reduce our ecological footprint and aim to be self sufficient.

What is going on here? All planning entails a balance of risks.

What we do know, from our own observations and from a virtual consensus amongst the scientific community, is that the status quo (doing nothing) is a dire risk, the toll on humanity ranges from the current ones (serious droughts, spread of diseases and freak storms) to outright calamity for the whole human race.

Doing something about it means doing something serious enough to limit that risk. No point pussyfooting around, or we may as well do nothing and watch it all happen.

It’s good that there are a few people out there warning against over-reacting (even if they are simply in denial of the problem) because we do have to be careful to tread wisely.
But doing nothing is, by far, the biggest risk of all.

If you are heading for a cliff top at high speed it could be argued not to swerve too much because you may roll the car. True, but do you then just go over the cliff while being cautious about the best way to avert disaster?

The proverbial split second we have to respond to climate change is at this point in history, folks. It requires courage and wisdom, not faltering resolve.