Abstract of a paper delivered by Clive Hamilton to the Royal Society of the Arts last night in Sydney:

Recent analysis of carbon budgets shows that the timing and scale of emission reductions needed to avert dangerous climate change are well beyond any national policy proposals or anticipated international agreement.

There have been two alarming developments in recent years. First, climate scientists are reporting that the scale of damages associated with warming of 2°C is much worse than previously believed, suggesting that more stringent emission cuts are essential.

Secondly, global growth in greenhouse gas emissions is much higher than anticipated a few years ago and the world is now on a warming path that is worse than the worst-case scenario. Rather than decarbonising, the world is carbonising at an unprecedented rate.

Analysis reviewed in this paper shows that, under the most optimistic assumptions about the timing and extent of global greenhouse gas emission reductions, cumulative emissions over the next few decades will result in atmospheric concentrations reaching 650 ppm of CO2-e, associated with warming of 4°C or more before the end of the century, a temperature not seen on Earth for 15 million years.

It now seems almost certain that, if it has not occurred already, within the next several years enough warming will be locked into the system to set in train positive feedback processes that will overwhelm any attempts to cut back on carbon emissions. Humans will be powerless to stop the shift to a new climate on Earth, one much less sympathetic to life.

Read the full paper here.