By Richard Black, BBC News.

The UN sustainable development summit in Brazil has ended with world leaders adopting a political declaration hammered out a few days previously.

Environment and development charities say the Rio+20 agreement is too weak to tackle social and environmental crises.

Gro Harlem Brundtland, author of a major UN sustainable development report 25 years ago, said corporate power was one reason for lack of progress.

Nations will spend three years drawing up sustainable development goals.

They will also work towards better protection for marine life on the high seas.

But moves to eliminate subsidies on fossil fuels – recommended in a number of authoritative reports as likely to boost economies and curb CO2 emissions – came to naught.

Plans to enshrine the right of poor people to have clean water, adequate food and modern forms of energy also foundered or were seriously weakened during the six days of preparatory talks.

And many governments were bitter that text enshrining women’s reproductive rights was removed from the declaration over opposition from the Vatican backed by Russia and nations from the Middle East and Latin America.

‘No leadership’

The UN had billed the summit as a “once in a generation chance” to turn the global economy onto a sustainable track.

“It absolutely did not do that,” said Barbara Stocking, chief executive of Oxfam GB.

People gathering water at a man-made water hole, in South Sudan’s Upper Nile state The rights of poor people to have access to clean water were not enshrined as hoped

“We had the leaders of the world here, but they really did not take decisions that will take us forward,” she told the BBC.

“It was a real lack of action that is very worrying, because we know how difficult the situation is in much of the world in terms of environment and poverty, and they did not show the leadership we needed them to bring.”

The president of the most impoverished country in the western hemisphere, Haiti’s President Michel Martelly, said the summit could have delivered more.

“I feel like these poor countries, these countries that are always being hit by catastrophe – things have not changed much,” he told the BBC.

“So on this summit I will say that much more effort needs to be done so we can correctly and precisely come out with resolutions that will have an impact on the lives of people being affected.”

Cash concern

Developing countries had argued that they needed financial assistance in order to meet the costs of switching onto a green development path.

But with the US in an election year and the EU deep in eurozone mire, any mention of specific sums was blocked.

As a consequence, developing countries refused to let the declaration endorse green economics as the definitive sustainable development path.

Prof Jeffrey Sachs, the Columbia University economist and special adviser to UN Secretary-General Ban Ki-moon, said support was needed.

“Those of us who look at this day in, day out know that many poor countries need that kind of help,” he said.

A man rides his bicycle past the cooling tower and chimneys from a coal-burning power station in Beijing Developing countries had said they needed financial help to adopt greener forms of development

“And it does not do any good to cite large ambitious promises many years out, and then behind the scenes to say ‘we’re not going to talk about how they’re going to be fulfilled.”

But Lisa Jackson, Administrator of the US Environmental Protection Agency (EPA) and deputy head of the US delegation here, said the US was fully behind the “green economy” – and that the summit could help deliver the vision.

“The negotiated document, which is really the first time we have a multilateral document that talks about the green economy that has broad-based support – that is a big push,” she said.

“But probably more important are the connections that are being made between businesses large and small, civil society, academia and of course governments at the national and sub-national level – all those things are pushing the green economy forwards.”

Norwegian would

The need to put the world on a sustainable track, and the perils of not doing so, were outlined most influentially in a 1987 commission chaired by Gro Harlem Brundtland, then prime minister of Norway.

Speaking to BBC News in Rio, she reflected on the lack of real progress since then.

“Obviously when you look back 25 years now, less than one would have expected has happened – that’s clear – but you can’t think you can turn the world round in 25 years,” she said.

She said there were “complex reasons” why governments had been unable to take the vision further – including the power of corporations. “I think [the allegation] is justified – it’s not the whole truth but it certainly is a big part of it,” she said.

“In our political system, corporations, businesses and people who have economic power influence political decision-makers – that’s a fact, and so it’s part of the analysis.”

The next key date on the sustainable development journey is 2015.

The sustainable development goals should be decided and declared by then; also, the UN climate convention will have what some, with trepidation, are calling its “next Copenhagen” – the summit that should in theory usher in a new global agreement with some legal force to tackle global warming.