Climate change: can disaster still be avoided?
November 14th, 2007 by Jim JustThe 27th session of the Intergovernmental Panel on Climate Change (IPCC) is being held in Valencia, Spain. It will conclude Saturday with a report expected to convey the message that the worst impacts of climate change can still be avoided if we act quickly and decisively.
A new report by Carbon Equity, Target Practice; where should we aim to prevent dangerous climate change, observes that the thawing of the Arctic ice is happening much faster than anyone had ever thought, nearly 100 years ahead of IPCC projections and before we have even reached a 1 degree rise in global temperature. We need to reassess our concept of where a ’safe’ limit might lie. Given that 2 degree is no longer a ’safe’ limit, where might that limit be?
The report finds that the widely-promoted 2ºC goal is not credible. Such an increase in average global temperatures would initiate climate feedbacks on earth and in the oceans, on ice-sheets and on the tundra, taking the earth past significant tipping points. Holding to 2 degrees as a target is, in effect, condemning humanity to runaway climate change.
Proposals for a 60% cut on 1990 levels by 2050 imply a 3ºC target. The last time temperatures were 3°C higher than our pre-industrial levels, the northern hemisphere was free of glaciers and ice sheets, beech trees grew in the Transantarctic mountains, sea levels were 25 metres higher.
In order to avoid the loss of the Arctic icesheet, a safe target would be 0.5ºC. We therefore propose that a safe-climate temperature increase cap be 0.5ºC and greenhouse gas level of 320 ppm CO2e.
To return to the safe zone we need to bring the global temperature and the atmospheric greenhouse gases down from their present levels. This means that no further greenhouse gases should be added to the air and there needs to be a very significant reduction of CO2 using natural carbon sinks and deliberate human capture and sequestration.