Met Office warns of need for drastic cuts in greenhouse gases from 2010

• 3% a year may keep temperature rise to 2C
• Study says inaction could have dire consequences

A burnt-out firefighters’ truck after forest fi res devastated southern Greece during a heatwave last August. (Photograph: Louisa Goulimaki/AFP/Getty Images)

The world will have to take drastic action within two years to reduce greenhouse gas pollution if it is to avoid the worst effects of climate change, a new study warns.

Weeks before world leaders meet to discuss the next big international treaty on cutting emissions, the scale of risk posed by failing to act rapidly is spelt out today by the UK Met Office's Hadley Centre.

The study shows that cutting global emissions by 3% a year from 2010 offers the only possible hope of avoiding a global temperature rise of more than 2C -- widely recognised as the threshold beyond which the worst impacts of sea level rise and drought become a significant risk.

In the early years, at least, responsibility for such deep cuts in emissions would have to be borne by the UK and other rich countries, which are responsible for most of the historic build-up in emissions.

It raises the prospect of far-reaching changes, including a rapid spread in community renewable energy and wave and tide power, improvements in public transport, big shifts to cycling and walking and changes in diet. It would also lead to huge pressure for the UK to abandon plans for a third runway at Heathrow and new coal-fired power stations.

The warning from the Hadley Centre is likely to cause widespread concern, especially as the Met Office has a reputation for taking a cautious approach. It advises the UK government, the United Nations and other governments and businesses.

Writing in today's Guardian, Vicky Pope, the Met Office's leading adviser on climate change to the government, warns that failure by governments to agree to "large and early" cuts or to meet those targets in future "could have worrying and significant consequences for the world's climate."

Such a deal will be regarded as all but impossible by many experts as the 2010 deadline is soon after a big international meeting in Copenhagen in December next year, when the UN hopes a treaty will be signed.

Andy Atkins, executive director of Friends of the Earth, said, "Tactically we have to point out the opportunities and make it clear to them we have to act."

Others called for the Met Office's warning to spur the UK and other countries to more urgent action at the big UN meetings in Poznan, Poland, in December and in Copenhagen at the end of next year, when a replacement for the Kyoto protocol is due to be agreed.

So far, leaders of the G8 group of leading industrial nations have signalled support for a 50% cut in emissions, but have not pledged higher targets for their own countries.

"The new science should raise our ambition levels rather than [make us] back off," said Paul Cook, advocacy director of the development charity Tearfund. "It's a big shift but it's do-able."

The Hadley Centre analysed three possible agreements to cut global emissions, ranging from "early and rapid" to "late and slow" cuts, and compared them with what would happen if no action were taken. It found that if cuts begin in 2010 and quickly reach 3% a year then the most likely mid-range forecast temperature rise would be 2C above pre-industrial levels by 2100. This is based on cutting emissions by 50% globally by the middle of the century, as advocated by the UN and accepted by many national governments.

By comparison, an "early but slow" decline, beginning in 2010 but at a more modest level of 1% a year, would lead to likely temperature rises of 2.9C by the end of the century, and a "late and slow" decline beginning in 2030 would generate likely temperature increases of 4C by 2100.

At 2C, scientists have warned that at least one-fifth of species are at risk of extinction and 1 to 2 billion people could suffer increased water stress; above 2C plants and soil significantly reduce the amount of carbon they absorb; and above 4C experts warn there is a danger of passing a "tipping point" at which methane release from permafrost and the collapse of big ice sheets accelerate the problems.

The Met Office's researchers also looked at what would happen if reductions began later but were then steeper: "It looked very like the 'early but slow' [scenario]," Pope told the Guardian. The reason delays cause greater impacts is that in the intervening years carbon would build up in the atmosphere, where it remains for a century.

Even more worrying than the "most likely" central projections are the "worst case outcomes," says Pope. Even for the optimistic "early and rapid" cuts there was a chance the temperature could rise by 2.8C -- and any delay in making cuts ran the risk of the global thermometer coming close to or exceeding the crucial 4C figure.

Professor Bob Watson, chief scientific adviser for the Department for Environment, Food and Rural Affairs, said the results showed the urgency of an international agreement at the UN's conference in Copenhagen. "If we act now, maybe we have got a fighting chance," he said.

Link to article: http://www.guardian.co.uk/environment/2008/oct/01/climatechange.carbonemissions1