This week, up to 100,000 people are streaming into Rio de Janeiro for the year's biggest international event – the UN Summit on Sustainable Development to be held on Wednesday and Thursday.

It is more popularly known as the Rio+20 Summit, to commemorate the landmark Earth Summit of 1992, which brought the environmental crisis into the mainstream of political life.

Rio+20 is meant to reaffirm the political commitments made then, and to come up with new action plans to counter the crises which have become much more serious than 20 years ago.

But the negotiations to produce an outcome document have got mired in new concepts, especially the "green economy", and now the developed countries appear reluctant to a simple reaffirmation of the original Rio equity principle, or to re-commit to provide finance and technology transfer.

It is now disappointingly clear that there will be no major breakthroughs in Rio. But Rio+20 can still be a success if it reaffirms old commitments and launches new processes to strengthen institutions and initiates new goals and action plans.

The first contested issue is whether the political commitments made in 1992 will be reaffirmed as still valid today. For developing countries, a "must" is the reaffirming of the Rio principles, especially the common but differentiated responsibilities.

Under the CBDR, all countries have the duty to act but developed countries have to do the most in environmental action plus provide finance and technology transfer to developing countries so that they can move towards sustainable development.

However, developed countries are showing reluctance to update their endorsement of CBDR. Some, especially the United States, want developing countries (except perhaps the poorest) to take on similar obligations as the North. Failure to endorse CBDR would be seen as a big retreat from Rio92.

The second issue is the green economy, designated as a priority issue of Rio+20. The problem is that there is no internationally agreed definition of this term. Developing countries are concerned that the green economy will replace sustainable development as the key paradigm in the environment-development nexus with the loss of the Rio 92 consensus. They are also worried that the term may be misused as grounds for trade protectionism and aid conditionality.

They want it to be defined as just a tool to achieve sustainable development and not a new policy prescription or framework.

However, developed countries believe the green economy is a new important concept that can lead to changes in the way economies are organized. The Europeans want Rio to endorse a UN green economy roadmap with environmental goals, targets and deadlines, which is facing resistance from many.

The third issue is the sustainable development goals, which are expected to be one of the key "deliverables" in Rio. The developing countries have accepted SDGs as a concept and an operational tool. They want the three pillars (social, economic, environment) to be represented in a balanced way in selecting the goals, and they are concerned that the European Union has put forward only environment goals.

Rio+20 will launch a post-Rio process to decide on the goals and their details, since it is too late to come up with a definitive list. However, most developed countries, especially the EU, want some SDGs (energy, water, oceans, land issues) to be listed as priority goals, so that Rio+20 can have some tangible results.

However, the developing countries including China do not want to mention any issues, since any list of SDGs must have balance among the three pillars and there is no agreement yet on how to select SDGs.

Another dispute is on who should formulate the SDGs, after Rio. Developed countries want the UN Secretary General and his selected experts to draw up the SDGs, whereas the G77 and China want the governments to do it.

A fourth issue is the institutional framework for sustainable development, or how to ensure the institutions are up to the task. There are various proposals, including creating a Sustainable Development Council that meets regularly and a high-level political forum on sustainable development with annual ministerial meetings.

There is also broad agreement that the United Nations Environment Programme has to be strengthened and given more resources. However there is an on-going dispute as to whether the UNEP should become a UN specialized agency (which is strongly advocated by European countries and by Africa) or retain its status as a program but be strengthened (which most other countries prefer).

Finally a hotly contested issue is providing finance and technology to developing countries to enable their switch to environmentally sound development paths, as was successfully argued 20 years ago.

The developing countries insist that Rio+20 should at least renew the original commitments of new and additional financial resources, and that efforts are made to meet the aid target of 0.7 percent of GNP. However even these minimal aspects are being resisted by some developed countries, especially the US and Canada.

The developing countries have proposed that developed countries provide at least $30 billion a year in 2013-17 and $100 billion a year from 2018 onwards, and set up a sustainable development fund. The developed countries have objected to both.

On technology transfer, the situation is equally bleak. All major developed countries have objected to reaffirming the 1992 commitments to provide technology transfer on concessional and preferential terms to developing countries.

Instead they have proposed the term "voluntary transfer of technology on mutually agreed terms" which implies sale of equipment on commercial terms, which is opposite to the technology transfer concept. Even mild language to have a balanced approach to IPRs has been rejected, as has the concept of enhanced access by developing countries to environmentally sound technology.

The above issues will eventually have to be ironed out, but how it is done will determine whether Rio is a success. Success will require trust to be rebuilt by reaffirming the principles and action framework of Rio 92.

The commitments made on providing finance and technology transfer to developing countries have to be renewed and made relevant to present needs. Action plans for various subjects should be endorsed. A commitment to bring about new or at least stronger institutions has to be made. And agreement has to be reached on the new issues that have consumed a lot of the energy and time of the preparation for Rio+20 – the green economy and sustainable development goals.