Brazil has set a deadline for agreeing to the plan by Monday, so that the three-day gathering, which aims at reviving the momentum of the 1992 Earth Summit, is not wrecked by squabbles.
But sources attending the UN Conference on Sustainable Development in Rio said late-night talks on the 50-page draft were mired in discord on many issues.
They include text on climate-altering fossil fuels, promoting the green economy and providing funding for poorer countries.
Another problem area is how to strengthen world governance for the environment, an area where national sovereignty is jealously guarded.
Negotiators were also wrangling over “Sustainable Development Goals” – SDGs – that would replace the UN’s Millennium Development Goals after these objectives expire in 2015.
“The initial reactions of governments indicated that although the new text is accepted as the basis for negotiations, it has not resolved most of the key issues,” said Martin Khor, executive director of the South Centre, an intergovernmental thinktank of developing countries based in Geneva.
“The old battles will thus resume (today),” he said. “Given the limited time left, it will be a real uphill task to get an agreement.”
Around 116 heads of state and government are expected to attend the summit starting Wednesday, although several big hitters – US President Barack Obama, British Prime Minister David Cameron and German Chancellor Angela Merkel among them – will be absent.
The meeting is designed to crown a 10-day event, bringing together some 50,000 activists, policymakers and business executives, which is intended to showcase sustainable development.
Twenty years have elapsed since the first Earth Summit, where the community of nations declared war on poverty and environment ills. They set up three conventions to tackle climate change, desertification and species loss and drew up a bible, Agenda 21, intended to guide their actions.
But on almost every count, the planet’s health is worse than ever.
Scientists warn that emissions of climate-altering fossil-fuel gases are scaling ever-higher peaks, a trend that will stoke worse floods, droughts and storms and imperil small island states with rising seas.
Biodiversity loss, too, is unprecedented in the context of human history, and some biologists fear that a mass extinction is already underway.
The number of people living on $1.25 (one euro) a day fell from 1.9 billion in 1990 to around 1.3 billion in 2008. But in developing countries, nearly one person in two still lives on less than $2 (1.6 euros) per day.
Activists said they were worried that the final document would be gutted of ambition.
“Today I am very concerned and worried because the draft final document of the Rio+20 conference does not give proper attention to climate change,” former Soviet president Mikhail Gorbachev said through an organization he has set up, the Climate Change Task Force, to combat global warming.
“It looks like there is backsliding on this issue and that is what worries me so much, because without addressing climate change, all of the other problems and tasks that will be set by the final document will not be accomplished and will become meaningless.”
Jake Schmidt, international climate policy director at the Natural Resources Defence Council, based in Washington, said he hoped the summit would “turn this around.”
“It’s very disappointing that world leaders are arriving in the next couple of days and that they are presented with this document, which sets the tone for the challenges that we are facing but doesn’t leave us with any clear path for actually solving them.”