The agenda is ambitious.

The roughly 50,000 delegates from nearly 200 nations to this week's World Summit on Sustainable Development plan to tackle subjects ranging from biodiversity to energy and fair trade all in the name of fighting global poverty and improving the environment.

Many see the 10-day summit as an historic event, much like its predecessor, the Earth Day summit in Rio de Janeiro in 1992. But many of those involved already see storm clouds looming on the horizon.

The notable absence of US President George W. Bush has caused for furor in the days leading up to the summit. Bush, who said he has to focus on security and economic concerns with Sept. 11 coming up, will send Secretary of State Colin Powell instead.

The move amounts to a snub for the international leaders who tried to convince him to come along. The United Nations is said to have moved the date of the summit forward to end on September 4th, before the the one-year anniversary of the terrorist attacks on New York and Washington, so Bush could be present.

Common environmental policy: going, going ...

Europe is also feeling slighted. The past two years have seen an immense rift develop between Washington and the European Union on environmental policy.

Beginning with America's withdrawal from the Kyoto Protocol, which seeks to curb greenhouse gas emissions, in 2001 the EU and the US have seen hopes of a common environmental policy drift further and further away.

In June, at a preparatory ministerial meeting in Bali, disagreements over setting concrete targets for protecting the environment from the effects of industrial development led to deadlock between European and US delegates.

The EU's focus on setting timetables and targets doesn't gel with Washington, which says it needs more time to examine the problem of global warming. The Bush administration has said that it will take at least five years before it can complete research into global warming and finalize a strategy of its own.

Until then, the administration is loathe to shoulder any treaty that could, in its view, harm the US economy.

"The Kyoto Protocol would have cost our economy up to $400 billion (412.3 billion euro) and caused the loss of up to 4.9 million jobs," James Connaughton, chairman of the White House Council on Environmental Quality, told reporters.

The stance has caused for unrest and exasperation among the European Union's allies. The 15-member union wants a common policy that provides water and sanitation for half the roughly 2.4 billion people who are currently without it by 2015. But the US says it prefers a policy that would leave it up to countries to decide on their own environmental standards.

US has a plan, says delegation head

The head of the US delegation, Under Secretary of State John Turner said the US was not interested in timetables that were "no more than lofty aspirations that sit somewhere in the rafters at the UN.

"We are talking about providing real dollars for real projects," he said, referring to the large number of partnerships between governments, businesses and projects in developing countries which are a feature of the summit.

He added that the US had a well-thought-out plan of action to relieve poverty and promote sustainable development.

"The United States is committed to building a world where children can grow up free from hunger, disease and illiteracy," Powell said last week. "A world where all men and women can reach their human potential free from racial or gender discrimination, and a world where people can enjoy the richness of a diverse and healthy planet."

Observers say the absence of Bush and the somewhat maverick US stance on environmental subjects will give the first sessions of the summit little form or substance. Compromises on key issues might have to be deferred until world leaders meet on the final two days, according to delegates.

"This conference is an acid test of whether multinationalism works - whether we can get actions which provide development opportunity for the poor on clean water, sanitation and energy supplies,” said Ralf Fücks, president of the Heinrich Böll Foundation, a German think tank, told the British daily The Guardian.

The alternative, he said, is unilateralism and "national egotism."