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Legislative Assembly for the ACT: 2010 Week 11 Hansard (Tuesday, 19 October 2010) . . Page.. 4575 ..

greenhouse gas—

emissions due to human activities have grown since pre-industrial times, with an increase of 70% between 1970 and 2004.

The 25 to 40 per cent reduction negotiating range for developed countries proposed at the Bali conference a couple of years back was based on the 2007 IPCC assessment report. Yet it is worth observing for a moment that the outcomes of that report, even by the time they were released, were being superseded by new science. The science that comes out from the IPCC has been subject to what could be described as “political churn”; the science is inevitably politicised. Phrases that particular interests do not like are removed and de-prioritised; the degrees of certainty are watered down; consensus is found.

Let me be clear: I am not seeking to diminish the work undertaken by the IPCC. To the contrary, I commend them for the difficult task that they undertake. But the very nature and speed of the process mean that even when the IPCC report was first released, we were already seeing new science that indicated that the rate of warming is faster than was anticipated, with accelerating rates of carbon dioxide accumulating in the atmosphere, ocean temperatures increasing, and the loss of Arctic sea ice. We even see newer predictions that suggest that the impacts may be even more serious than anticipated.

The IPCC is the best process that we have for integrating the science, given that we are dealing with a global issue. But it is likely that we, as a global community, will find ourselves in an even stickier situation as new science is integrated into modelling and long-term feedback cycles kick in. The melting of the ice sheets, the exposure of the permafrost and the decreased capacity of the ocean to absorb more CO2 are likely irreversible consequences of emissions we are putting into the atmosphere right now. And there will come tipping points when human intervention will not be able to prevent these impacts from occurring. The effects will be devastating if the situation is left unchecked.

Global political negotiations on climate change, as difficult as they have been, have been trying to build a plan of action to keep global temperature rises below two degrees Celsius to prevent dangerous climate change. Yet in actual fact, two degrees gives us only a 50 per cent chance of a safe climate. These are pretty marginal odds when you are talking about the future of the planet.

A couple of weeks back, scientists from the University of Exeter in the United Kingdom released the results of a study in which they had looked at previous interglacial temperatures, and indicated that a two degree increase in temperature may actually not be safe at all, throwing significant doubt on the accepted premise that two degrees is what we should be aiming for.

I make these observations to highlight that the Greens and the government, in supporting the top end of the 25 to 40 per cent range, have made a judicious decision. We can take no comfort from recent science that anything less is required; indeed, at

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