I want to draw people's attention to 2012. For some, that's all about the Olympics. But I am more interested in what will happen in Rio de Janeiro. In June 2012 government representatives from around the world will be meeting there to discuss the transition to a green economy.

It will be the first time for 20 years that the United Nations has organised an event like this, in which environment, development, and economic policy can be considered together. The previous one was at the Earth Summit in Rio in 1992. That saw the signing of the Climate Change Convention, the Convention on Biological Diversity, and the Agenda 21 document. A lot of action followed: not enough of course, but some moves in the right direction. The Kyoto Protocol, and in the UK, the Climate Change Act and the setting up of the Sustainable Development Commission (sadly abolished on 31 March) can all be traced back to Rio.

In 2012, government representatives are returning to Rio, for a conference originally called 'Rio+20', though now being called 'Rio 2012'. Top of the agenda will be the green economy, and there will also be discussion of international governance structures, looking at how any of this can actually be implemented. One proposal already on the table from France is the upgrading of the United Nations Environment Programme, currently rather a poor relation compared to other world bodies such as the International Monetary Fund.

It will not be a meeting to put all of the 1992 agenda back into the melting pot. The conventions on climate and biodiversity will continue, and so will the action following from the Earth Summit on forests, desertification, and other topics. Rio 2012 will have a very focused agenda.

Increasingly environmentalists are realising that it is in ministries of economics, industry, and finance, that the big decisions about the environment get made, and not in environment ministries. Of course it is good that environment ministries exist at all, and for that a lot of the credit goes to a previous UN conference, the Stockholm Environment Conference in 1972, where many of the issues which have been grappled with ever since were first put on the international agenda. Rio+20 is also Stockholm+40.

We don't have a lot of time left. Rio in June 2012 could act as a rallying point to galvanise action, and move forward on what I have been calling in this blog the good transition, because if we don't, we are in for a bad transition as the situation is going to change one way or the other. Currently the world is on the route to increasing droughts, floods, extinctions, and general deterioration in the ecological underpinnings of our lives.

The UK Government appears not to understand this. They have recently published an embarrassingly pathetic vision document about sustainable development, which they pretend will in some way make up for their vandalism in ending the Sustainable Development Commission and the Royal Commission on Environmental Pollution.

This is at a time when rising commodity prices – for oil, food, metals, etc – threaten all of the Government's economic policy targets. They see these as outside factors over which they have no control, and no blame. However the clash between rising demand and limited supply in a finite world is the perfect recipe for these commodity price rises to continue. Only a transition to a lower-carbon, more resource-efficient, and far more ecosystem-conserving future economy is going to solve that problem. Even those in economics, government, and business who are not so concerned about the environment for its own sake must surely give that some of their attention. If not now, maybe in 2012.

This article was also published in the Guardian online