By Alister Doyle, Environment Correspondent

ACCRA, Aug 21 (Reuters) - About 160 nations resumed talks on a new climate treaty in Accra on Thursday with Ghana warning that time was short to work out a deal that will need billions of dollars a year to help the poor adapt to global warming.

"The clock is ticking," Ghanaian President John Kufuor told the opening session of the Aug. 21-27 talks in Accra, meant to work on details of a new U.N. deal to combat global warming that will be agreed in Copenhagen at the end of 2009.

"We need more than rhetoric to make progress in the next 12 to 18 months," he told about 1,000 delegates in a conference hall in Accra. The talks are the third this year of a series of eight U.N. sessions due to end with a treaty in Copenhagen.

Kufuor said there were damaging signs of climate change in Ghana -- rainfall had decreased by 20 percent in the past 30 years, while up to 1,000 square km (386.1 sq mile) of land was at risk in the Volta Delta due to sea level rises and floods.

"Climate change makes development harder and more expensive," he said.

He backed a U.N. deal under which poor nations would agree to slow the rise of their emissions, mainly from burning fossil fuels, while seeking to curb poverty in return for a package from rich nations that included funding and clean technology.

Estimates of the costs of adapting to a changing climate, such as flood prevention, drought-resistant crops or defences against rising seas "differ enormously but run to tens of billions of dollars per year," he said.

And he said that global warming was not only a problem for poor nations. "The entire human race is under threat, no matter its geographical location," he said.

FOOD PRICES

Yvo de Boer, head of the U.N. Climate Change Secretariat, also urged delegates to speed up talks after scant progress in previous meetings in Bangkok and Bonn this year against a backdrop of slowing economic growth and high food and fuel prices.

"Time is short ... negotiations need to speed up," he said. He said Africa had been the "forgotten continent" in the climate debate and among the most vulnerable, with up to 250 million people threatened by water shortages by 2020.

Denmark's Climate and Energy Minister Connie Hedegaard, who will preside at the U.N. talks in Copenhagen next year, said the Accra meeting had to work on mid-term targets, such as 2020, for cuts in emissions of greenhouse gases by developed nations.

She said that a deal by the Group of Eight industrialised nations in Japan in July to a vision of halving global emissions by 2050 was too distant.

"Agreeing to halve emissions by 2050 is one thing. We must establish a mid-term target," she said.

The Accra talks will look at ways to broaden the current Kyoto Protocol, which binds 37 developed nations to cut emissions by 5 percent below 1990 levels by 2008-12.

Delegates will look at new mechanisms, such as credits to slow the rate of tropical deforestation. Burning of forests contributes up to about 20 percent of manmade greenhouse gases, U.N. studies show.

And delegates will consider whether to introduce sectoral targets, such as on the amount of greenhouse gases emitted to produce a tonne of steel or cement.

The WWF environmental group said the talks needed an "Olympic spirit". "The Olympic motto - 'swifter, higher, stronger' has to guide the discussions," it said. -- For Reuters latest environment blogs click on: http://blogs.reuters.com/environment/ (Editing by Mike Collett-White)

AlertNet news is provided by