The United Nations Conference on Sustainability, Rio+20, began today (20 June), amid cries from environmentalists that the negotiated agreement is a “colossal failure”.

The conference marks the 20th anniversary of the 1992 United Nations Conference on Environment and Development (UNCED) and has seen over 100 heads of state and government officials from across the globe convene in Rio de Janeiro to renew their commitment to sustainable development.

The summit has been marred by reports of widespread disagreement on key issues, including debates over fossil fuel subsidies and sustainable development goals (SDGs), which have left the negotiated text in a weakened form. Such was the disagreement among delegations that negotiators were still in discussions with government officials on Tuesday night, just hours before the conference was due to start.

Environmentalists including WWF and Greenpeace hit out at the lack of action listed in the resulting draft agreement yesterday (19 June), with WWF calling the text a “colossal failure” and Greenpeace saying it has “failed on equity, failed on ecology and failed on economy”.

WWF Director General, Jim Leape severely criticised the negotiated text, saying: “Despite a late night negotiating session, the revised text is a colossal failure of leadership and vision from diplomats. They should be embarrassed at their inability to find common ground on such a crucial issue.

"Now it’s up to world leaders to get serious about sustainable development and save this process. If they approve what’s on the table now without significant changes, they’ve doomed Rio+20 to ridicule.”

Leape added: “While some weak words have been removed, diplomats have swapped them with toothless language. This includes tongue twisters like ‘commit to the progressive realisation’ and several promises to ‘recognise’ problems and solutions. They’ve added some positive actions around oceans protection. But, the text has lots of words that ‘commit’ parties to nothing – such as ‘commit to promote’ and ‘commit to systematically consider’.”

“Two years and one late night of negotiations later, diplomats in Rio are letting the world down”, said Leape. These sentiments were echoed by Kumi Naidoo, Greenpeace’s International Executive Director: “Rio+20 has turned into an epic failure… We were promised the 'future we want' but are now being present[ed] with a 'common vision' of a polluter’s charter that will cook the planet, empty the oceans and wreck the rain forests. This is not a foundation on which to grow economies or pull people out of poverty, it’s the last will and testament of a destructive twentieth century development model.”

WWF has now inflated a hot air balloon with a banner saying ‘Get SeRIOus+20’ in English and Portuguese outside the main route into the summit.

The EU has also released a statement admitting that although Europe thought the draft agreement was in ‘broad terms’ a declaration of ‘the future we want’, a number of ambitions were not fully achieved. ‘The EU has secured engagement in a number of areas such as water, oceans, land and ecosystems, food, and sustainable consumption and production (SCP)... However the EU was not successful in getting agreements on specific targets in a range of other areas.’ Though the EU’s emphasis of a green economy has been recognised as an important tool for achieving sustainable development, other suggestions by the EU, such as the establishment of a World Environmental Organisation were not successful.

Rio+20 will primarily focus on two themes: a green economy that will see sustainable development and poverty eradication, and the development of an institutional framework for sustainable development. Other issues that will be discussed at the conference include: oceans; water; food security and sustainable agriculture; sustainable, low-carbon transport in emerging and developing economies; sustainable cities and green jobs; and social inclusion.

The 1992 summit concluded with three global treaties adopted worldwide: combating climate change; protecting wildlife; and tackling land degradation. A 40-chapter global agenda for tackling the world’s environmental problems, Agenda 21, was also adopted. It is not expected that any global treaties will be adopted from Rio+20.

Many leaders of Western countries will not be attending Rio+20, including UK Prime Minister David Cameron, US President Barack Obama and German Chancellor Angela Merkel.

An exclusive copy of the draft text can be found on the Guardian website.