Environmental pressure groups have written off the Rio+20 summit beginning today as "pathetic" and a "colossal failure of leadership".
Deputy prime minister Nick Clegg is attending the United Nations Conference on Sustainable Development summit on behalf of Britain.
Expectations were already relatively low for the summit, which is not being attended by senior world leaders including German chancellor Angela Merkel, US president Barack Obama and David Cameron. Former UK prime minister John Major attended the original Rio de Janeiro summit in Brazil 20 years ago.
But after the negotiating text which the 130 world leaders will discuss was released the mood of environmental campaigners dropped still further.
"This is not a foundation on which to grow economies or pull people out of poverty," said Kumi Naidoo, Greenpeace's international executive director.
"It's the last will and testament of a destructive 20th century development model."
Jim Leape, the director-general of WWF, said "weak words" had been replaced with "toothless language".
"Despite a late night negotiating session, the revised text is a colossal failure of leadership and vision from diplomats," he commented.
"They should be embarrassed at their inability to find common ground on such a crucial issue.
The 50-page international agreement being discussed by leaders proposes the creation of sustainable development goals for both developing and developed countries to work towards.
"We're proposing a package of sustainable development goals to rally the international community around ensuring that all people, everywhere, have access to food, clean water and green energy," Mr Clegg wrote in an article for the Guardian newspaper.
"Agreeing these will be a huge undertaking – but this week we need to get them off the ground.
Mr Clegg also called on national governments to broaden their understanding of wealth beyond GDP and emphasised the need to "bring business in". He wants more corporate accounts to include 'sustainable reporting'.
The summit began with a pre-recorded speech from the Prince of Wales, who warned that climate change and global food security need urgent action.
"I have watched in despair at how slow progress has sometimes been and how the outright, sceptical reluctance by some to engage with the critical issues of our day have often slowed that progress to a standstill," Prince Charles said.
"As I speak, the world's rainforests continue to be destroyed, wiping out so much of the world's vital biodiversity and removing our chances of storing carbon naturally.
"And we continue to ignore the painful lessons of the so-called green revolution in India by intensifying our food production methods in such blinkered, chemically and technologically-based ways, that the land and the oceans are now both beginning to fail."