Is global warming difficult to reverse? - 11 March 2009
Global warming is going to be difficult to reverse, even if emissions stop abruptly, according to new research published in the journal Environmental Research Letters.
For the first time, scientists have used the most complex type of climate model, which moves carbon around the atmosphere, oceans and vegetation and soils, to see what happens if emissions are stopped abruptly. This could be representative of global “de-carbonisation” of the world in the event of reaching dangerous levels of climate change. They found that even with zero emissions from human activities, the natural world takes, not decades, but hundreds of years to return to lower temperatures.
Co-author Dr Chris Huntingford from the Centre for Ecology & Hydrology compared the climate to a spring. He commented, “Our emissions have pushed the climate system hard and fast in one direction. But when we let go, the natural parts of the system do not bounce back quickly; they act more like a weak spring. If you stop emitting carbon dioxide, you might expect levels, along with associated temperatures, to fall back down quickly. But these latest model projections show that the natural system takes a long time to reset.”
The new findings support research published in January and led by US climate researcher Dr Susan Solomon. Solomon showed how changes in surface temperature, rainfall, and sea level are largely irreversible for possibly more than 1000 years after carbon dioxide emissions stop.
The international community’s target is to slash emissions to 50% of 1990 levels by 2050. Accounting for economic growth in developing countries, UK emissions must drop by 80%. But what if countries overshoot their targets? This is what the climate scientists wanted to investigate in this research. Dr Huntingford adds, ”The results show that forcing temperatures beyond what some have described as dangerous levels will make it difficult to get back to a ‘safe’ level.”
The research involved scientists from the Met Office Hadley Centre, the Centre for Ecology and Hydrology, and Manchester Metropolitan University.
Additional information
The paper ‘How difficult is it to recover from dangerous levels of global warming?’ is published in Environmental Research Letters, an open access journal. A copy of the paper can be found here (external link).
The research was funded by the joint DECC, Defra, and MoD integrated climate programme and the Natural Environment Research Council.
CEH’s Biogeochemistry science programme
Research carried out by Dr Chris Huntingford
Media enquiries for Dr Chris Huntingford should be directed to the Centre for Ecology & Hydrology press office.
