Protecting societies against the impacts of climate change will be much more expensive than previously¹ believed, according to a new analysis.

一项新的分析显示，保护社会免受气候变化带来的影响所耗费的钱财比先前预算的多很多。

In 2007, the UN climate convention（大会，协定） came up with a sum of $49-171bn per year.

The new report says the UN sums omitted important factors and the true cost will be two to three times higher.

Developing nations want rich countries to provide major sums for adaptation as part of the new UN climate deal due to be agreed in Copenhagen in December.

"The amount of money on the table at Copenhagen is one of the key factors that will determine whether we achieve a climate change agreement," said lead author Martin Parry, a visiting research fellow with the Grantham Institute for Climate Change at Imperial College London.

"But previous estimates of adaptation costs have substantially misjudged the scale of funds needed."

Professor Parry co-chaired the Intergovernmental Panel on Climate Change (IPCC) working group on climate impacts for its 2007 assessment².

The new report - issued under the aegis³ of（在……支持下） the International Institute for Environment and Development (IIED) and the Grantham Institute - says that some aspects of the UN estimates were wrong by a factor of more than 100.

Call to caution

The UN climate convention (UNFCCC) made its assessment（评估） in 2007 after the IPCC concluded the task was too difficult; and Professor Parry suggested it had been done in a hurry, with some vital caveats⁴（警告） ignored in subsequent deliberations.

A spokesman for the UNFCCC defended the process but said the organisation⁵ had a responsibility to be conservative.

"Looking at what was out there in 2007, these were best estimates, which we simply collected; and we had to err⁶ on the side of caution," he said.

Recently the UNFCCC's executive secretary Yvo de Boer has tended to use the figure of $100bn (£60bn) per year.

Professor Parry told BBC News that a key point of the new report, Assessing the Costs of Adaptation to Climate Change, was that it included "bottom-up" as well as "top-down" analyses.

"One study shows the cost of adapting a single watershed⁷（流域） in China - that's one of the few case studies that's been done - comes in at a billion dollars a year," he said.

"So when you start adding up the various figures you soon start to exceed the global number (in the UN's analysis)."

He said UNFCCC calculations had taken into account only half of the extra disease burden due to emerge from climate change, assumed low levels of future development in Africa (so giving less infrastructure⁸ to protect), used low estimates for sea level rise and had not included the economic costs of nature loss.

Financial key

Securing funds for climate protection, or adaptation, is a key priority for developing countries in the run-up to the Copenhagen conference, which is supposed to secure a new global agreement supplanting⁹（排挤，取代） the Kyoto Protocol¹⁰.

Earlier this week the African Union suggested it would be asking for $67bn (£40bn) per year for Africa alone.

"Finance is the key that will unlock the negotiations¹¹ in Copenhagen," said IIED director Camilla Toulmin.

"But if governments are working with the wrong numbers, we could end up with a false deal that fails to cover the costs of adaptation to climate change."

A priority for the UN climate secretariat is to secure mechanisms¹² that ensure sums of any size can be raised without constantly having to re-negotiate new terms.

Most is expected to be raised through levies¹³ on carbon trading, but Mr de Boer believes developed countries will need to pledge up-front sums in the region of $10bn per year.

Further analyses from the World Bank and management consultants¹⁴ McKinsey and Company are due out before the Copenhagen talks.