A new intergovernmental panel would not be the best way of tackling the multifaceted challenges of sustainable development.
Whatever its faults, the Intergovernmental Panel on Climate Change (IPCC) has successfully brought global warming to the attention of policymakers.
It has marshalled scientific evidence for climate change and its potential impacts in a way that most policymakers (with some notable exceptions) have been able to accept. And success has come despite highly publicised errors most recently over how fast Himalayan glaciers are likely to disappear.
Inevitably, this success makes the panel an example that others want to follow.
This article is part of our coverage of preparations for Rio+20 the UN Conference on Sustainable Development which takes place on 20-22 June 2012. For other articles, go to Science at Rio+20
Now, stakeholder groups and others are suggesting that the UN Conference on Sustainable Development (Rio+20), which takes place in Brazil in June, should agree on the need for a new intergovernmental panel, modelled on the IPCC, to address global sustainable development challenges.
But creating such a panel would be a mistake. Any attempt at building a global consensus on sustainability is likely to be undermined by scientific uncertainty and political manoeuvring. It could therefore set back, rather than advance, sustainable development.
The IPPC approach has obvious attractions in bridging the gap between science and policy. By establishing a clear scientific consensus, based on a wide range of robust research findings, the IPCC provides a solid platform for building policies to combat global warming and its impacts.
And because its reports are reviewed before publication by both the scientific and the political communities the IPCC has ensured high-level political buy-in for its conclusions. An independent, purely scientific organisation could not have achieved that.
Could the same be achieved for sustainable development? Probably not.
The first problem lies in disagreement over the mandate, already highlighted by two competing proposals on the table for potential endorsement at Rio+20.
One is favoured by the scientific community, as represented, for example, by the Future Earth Initiative set up by the International Council for Science. It seeks an Intergovernmental Panel on Global Sustainability that would focus on monitoring the natural (and social) processes that are proving unsustainable.
Other groups, including many development-oriented nongovernmental organisations, are backing an alternative suggestion formally tabled by the government of Indonesia, namely an Intergovernmental Panel on Sustainable Development.
This would have a broader but more controversial mandate, going beyond environmental protection to put sustainable development in a full social and economic context. It would identify not only how this might be achieved, but also the many factors, political and otherwise, that stand in the way.
Obstacles and complexities
A second problem is the sheer size, cost, and administrative complexity of the operation needed to run such a panel.
Already these issues have faced the Intergovernmental Panel for Biodiversity and Environmental Systems (IPBES), which has yet to become fully operational, five years after its initial proposal at the end of a multi-stakeholder consultation process.
Such obstacles will likely be bigger and more complex for a panel with a substantially broader mandate, whether to monitor global sustainability or sustainable development. And competition would be fierce among UN agencies wanting to take responsibility for it.
Crucially, the nature of the issue is a third reason why an IPCC model is inappropriate. The causes and impacts of climate change are directly amendable to scientific analysis; we can explain what is happening in scientific terms, even if we can't fully explain why.
Sustainable development is a different animal. There are many definitions of what it means, and what it looks like. Scientific analysis alone is unlikely to create a consensus around either what the problem is, or what needs to be done about it.
Three steps forward, not one step back
So what are the alternatives? Three are under consideration for endorsement at Rio+20, and should be supported by developed and developing countries alike.
The first, which is already contained in the 'zero draft', would be to set up a high-level group to produce regular reports on the state of the planet and the Earth's carrying capacity. These would be coordinated by the UN Secretary General and prepared in consultation with UN agencies and other international organisations.
This group would also be responsible for producing regular scientific assessments of key aspects of sustainable development (for example on renewable energy technologies) compiled by the world's top scientific and technical experts with representation from both developed and developing countries.
And the panel would set out options for policymakers but not prescribe which should be followed. Science 'on tap, but not on top', is the right model, in the UN as elsewhere.
The second, put forward by the advisory panel on global sustainability, would prepare a regular report on the outlook for global sustainable development (comparable to the annual Global Environment Outlook produced by the UN Environment Programme).
The group responsible for producing this should ensure that developing countries are fully represented. And it should also use a broad definition of sustainable development, taking full account of developing countries' views, rather than limiting its definition to scientific notions of natural and social processes.
The third move would create a relatively streamlined science advisory mechanism, again reporting directly to the UN Secretary General, made up of scientists and technical experts drawn from both developed and developing countries.
Agreeing on the need for regular state of the planet reports, sustainable development outlooks, and the science advisory mechanism, might appear relatively modest achievements to emerge from the Rio+20 meeting.
But taken together, they stand a better chance of leading to a viable way forward than any ambitious plan for a new intergovernmental panel based on the aspiration of reaching a global consensus.
This article is part of our coverage on Science at Rio+20.