Updated

Scientists and diplomats from more than 120 countries debated the urgency of changes in the Earth's climate Wednesday as they tried to finalize a report on global warming that will guide policymakers for decades to come.

In closed-door meetings, the delegates argued over revisions in the 21-page draft text, in one case making changes to highlight how global warming will reduce staple crops in countries such as China and India, where millions of people could go hungry.

The conference is due to release the report by Friday.

• Click here to visit FOXNews.com's Natural Science Center.

The text is a synopsis of a more than 1,400-page assessment by the Intergovernmental Panel on Climate Change, with contributions by more than 1,000 climate experts, on the impact of global warming and the vulnerabilities of economies, ecosystems and human health.

It will be presented at a Group of Eight leaders summit in June in Germany, during which the European Union will press President Bush to sign on to international talks to cut emissions.

The report also will be the basis for a conference in December in Indonesia to set an international framework for controlling the emissions of carbon dioxide after 2012, the expiry date of the Kyoto Protocol, which mandates emission curbs for industrial countries.

The United States, which has refused to coordinate action to curb greenhouse gas emissions with other countries, was playing a low-key role in Brussels so far, said delegates on condition of anonymity because they were not authorized to speak to the media.

Delegates said the talks were going slowly, with disputes over the level of confidence attached to the statement. Some countries wanted the wording either toned down or the level of certainty reduced, delegates said. The issue was handed to a smaller "contact group" to resolve.

"We have made too little progress so far," said Hans Verolme of the World Wildlife Fund for Nature, who is attending the sessions. "We want to make sure that what comes out in the end is crisp, well structured and understandable to the layman."

R.T.M. Sutamihardja, a delegate from Indonesia, said one difficulty was juggling the interests of each country in weighing the impact of climate change.

"If we want to include everything, we would need a bigger map," he told The Associated Press outside the conference room.

The report stresses that climate changes will have a more devastating impact on poor countries — and poorer citizens within rich countries — because they are less capable of adapting to shifts in weather patterns.

Many of the regions expected to be most affected already suffer severe water shortages and hunger, which will only get worse, the final report is to say, while some parts of North America and Europe will benefit in the short-term from milder winters and longer growing seasons.

The text is the second of four reports by the climate change panel. The first, issued in February, updated the science of climate change, concluding with near certainty that global warming is caused by human behavior.

Six years in the making, the panel's latest assessment is based on scientific data on changes that have occurred, including the earlier appearance of spring in temperate climate zones and the bleaching of tropical coral reefs from warmer sea water.

New reports appear almost daily. On Wednesday, scientists at the U.S. National Snow and Ice Data Center at the University of Colorado announced that the area of ocean covered by ice last month was the second lowest in recorded history, beaten only by the March 2006 record.

Walt Meier, a scientist at the center, said the Arctic sea report was a "milestone in a strong downward trend" reflecting warmer Arctic temperatures.