ACCRA (AFP) — Time is running out in the fight against global warming, the UN's top climate change official warned as a new round of UN talks got started here Thursday.

"There is little time left to get a solid negotiating text on the table. Clearly the clock is ticking," said Yvo de Boer, executive secretary of the UN Framework Convention on Climate Change.

"People in a burning house cannot afford to lose time in an argument," he said, citing an Ashanti proverb.

The Accra gathering must strive to "reach agreement on the rules and tools" that developed countries will use to cut greenhouse gas emissions, he told more than 1,600 delegates from 160 nations.

Ghana's President John Kufuor echoed the sense of urgency in his opening remarks, noting that his country was already suffering the consequences of global warming.

Rainfall in Ghana has decreased by 20 percent in three decades, and 1,000 square kilometres (400 square miles) of fertile agricultural land in the upper Volta Delta will be lost to rising sea levels and flooding if temperatures rise at their current pace, he said.

The expert-level meeting, which runs through August 27, is the third UN climate change conference since nations committed to adopting a binding climate accord no later than December 2009.

It is the last meeting ahead of a ministerial summit in Poznan, Poland in December where rich countries will be under intense pressure to nail down near-term commitments for reducing greenhouse gases.

The Group of Eight industrialised powers pledged to halve emissions by 2050, but critics say intermediate goals are needed.

"The real political commitment is short- and medium-term," Connie Hedegaard, the Danish Minister for Climate and Energy, told delegates.

"We have to speed up the pace. The negotiations here in Accra must deliver concrete results" about what technologies will be used to cut emissions, she said.

Africa is arguably the continent most vulnerable to the potential ravages of climate change, which range from extreme drought to violent storms to rising sea levels.

De Boer challenged delegates to be "ambitious," and said if they failed Africa would continue, in terms of climate change, to be the "forgotten continent".

He insisted that rich countries step up financial assistance to help Africa with global warming.

African produces the fewest emissions, he pointed out, but will likely well pay the heaviest price.

De Boer and Kufuor underlined the threat of deforestation, which is destroying one of nature's most powerful natural buffers against global warming.

The world's forests -- which are disappearing at a rate of about 30 million hectares (74 million acres) per year -- soak up more than 20 percent of the carbon dioxide in the atmosphere.

"Governments need to focus on reducing emissions caused by deforestation and forest degradation," and on how to reward countries that protect forests, said de Boer.

The problem is particularly acute in Amazonia, central Africa and Indonesia, experts note.

The World Wildlife Fund (WWF), an environmental group, called on the Accra meeting to adopt the Olympic motto of "faster, higher, stronger."

"Progress on substance ... must be swifter, the level of ambition by both developed and developing countries higher, and the measures to reduce CO2 (carbon dioxide) emissions stronger," said Kim Carstensen, director of the WWF's Global Climate Change Initiative.