The European Union's top environmental official has strongly criticized the United States and Australia, for rejecting a global treaty on reducing carbon emissions.

European Environment Commissioner Stavros Dimas accused Washington of maintaining a "negative attitude" on environmental cooperation, and said he cannot understand Australia's move to reject the 1997 Kyoto Protocol.

Dimas' comments came at the start of a four-day United Nations-sponsored meeting in Brussels of the Intergovernmental Panel on Climate Change - a network of more than 2,000 experts on global warming.

The grouping is tasked with summarizing a massive report that predicts dire consequences from global warming. It also seeks to determine whether humans can do anything to prevent it.

The closed-door meetings are expected to produce agreement on a draft U.N. study that predicts increasing global poverty and a scarcity of drinking water in much of the world by mid-century. It also predicts melting glaciers, rising sea levels and a host of vanishing species, unless emissions from heat-trapping gases are curbed.

Some information for this report was provided by AFP, AP and Reuters.