Government adviser warns of four degree global temperature rise

The UK government and business community should be preparing now for dangerous levels of climate change that could see average temperatures rise by four degrees centigrade on pre-industrial levels.

That is the stark warning from the Department for Environment, Food and Rural Affairs' chief scientific adviser Professor Bob Watson. In an interview with The Guardian newspaper today, he warned that while politicians were right to aim for less than a two degree rise, they needed to plan for rises of up to four degrees.

"There is no doubt that we should aim to limit changes in the global mean surface temperature to two centigrade above pre-industrial," he said. "But given this is an ambitious target, and we don't know in detail how to limit greenhouse gas emissions, we should be prepared to adapt to four centigrade."

Watson's warning is in line with those issued by large numbers of climate scientists who have argued that stabilising temperatures will require far deeper cuts in carbon emissions than most governments are planning. The UK, for example, is currently targeting a reduction in emissions of 60 per cent by 2050, but a number of recent studies have argued cuts in excess of 80 per cent will be required.

His comments were endorsed by the government's former chief scientific adviser, Sir David King, who warned that even if governments live up to recent commitments to cut emissions there was still a significant risk of larger-than-expected temperature rises.

"Even if we get the best possible global agreement to reduce greenhouse gasses on any rational basis you should be preparing for a 20 per cent risk so I think Bob Watson is quite right to put up the figure," he said.

However, Watson's forecast will still shock many given such increases are widely regarded as representing "dangerous" levels of climate change.

The Stern Report, for example, predicted that such a temperature increase would lead to a dramatic increase in the risk from coastal flooding, see a 30 to 50 per cent fall in water availability in regions such as southern Africa and the Mediterranean, and potentially result in up to 50 per cent of plant and animal species becoming extinct.

Scientists have also repeatedly warned that such an increase in temperature would also trigger so-called "feedback loops", where melting ice leads to higher sea temperatures further accelerating the retreat of ice floes or the melting of Siberian permafrost results in the release of more greenhouse gases.

Watson advised that as well as investing in adaptation measures the government should step up its investment in carbon capture and storage (CCS) technologies as the best hope of mitigating climate change.

He called for the development of up to 20 CCS pilot projects globally, adding that the emergence of a technology that could be retrofitted to coal plants in the developing world would underline the West's commitment to tackling climate change. "Without this technology we have a real problem," he added.

Watson's comments will also put pressure on the government to demonstrate that it is planning for climate change adaptation as well as mitigation.

Earlier this year, the government unveiled plans to invest an extra £450,000 a year in regional climate change adaptation measures, unveiled new plans to help tackle flood risks and launched a website advising firms and designers on how to prepare for climate change.

However, critics have repeatedly argued that the government's climate change strategy is weighted in favour of mitigation and not enough is being done to adapt to the risks presented by increased flooding, higher sea levels and heat waves.