Youba Sokona, Ottmar Edenhofer and Ramon Pichs-Madruga (left to right) will lead the IPCC's working group on mitigation. Credit: JUTTA NEUHAUS, POSTDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH

The UN Intergovernmental Panel on Climate Change (IPCC) named a spate of new leaders this month after some of the most complex elections the organization has seen.

Perhaps most famous for receiving the Nobel Peace Prize in 2007 with Al Gore for efforts to disseminate information on climate change, the IPCC last week re-elected as it chair Rajendra Pachauri during a meeting held from 29 August to 4 September in Geneva. Under his guidance, a team of fresh faces will lead an assessment of the scientific understanding of climate change and its implications over the next five years, culminating in a new 'synthesis' report in 2014.

Although the panel has firmly established the role of human activity in climate change, the scientists will now have their work cut out in evaluating how best to deal with the impacts. “The case for climate change, from a scientific point of view, has been made,” says Martin Parry, a climate scientist with the UK's Hadley Centre and former co-chair of the panel's working group on impacts and adaptation. “We're persuaded of the need for action. So the question is what action, and when.”

Despite the weighty business of electing a new bureau to tackle these questions, delegates at the Geneva meeting still found time to celebrate the panel's twentieth anniversary and to allocate the cash awarded them as part of the Nobel Prize to scholarships for young developing-world climate scientists.

Tough choices

Each round of the IPCC assessment process kicks off with an election, where national delegations vote for the panel's chairman, the co-chairs of its three working groups —which respectively deal with climate science, impacts and adaptation, and mitigation — and an array of vice-chairs.

Delegates in 2001 faced a memorable choice between Pachauri and science-adviser extraordinaire Bob Watson for the position of IPCC chair. In contrast, each of the working-group co-chair slots, which typically come in pairs shared by a developed- and a developing-nation scientist, passed to a single internationally respected expert without requiring a vote.

But after last year's glory, this time countries eagerly sought seats on the prestigious panel. According to Chris Field, director of the Carnegie Institution's Department of Global Ecology in California and new co-chair of Working Group II, nations stake “a flag in the ground” when they commit a big-name expert — and corequisite staff and funding, in the case of wealthy nations — to support the panel.

The IPCC is renowned for working on the basis of consensus, but this year the cooperative spirit collided with contests between multiple strong candidates. Even after regional caucuses whittled down co-chair nominees to those with the very best scientific reputations, three climatologists were still vying for the rich-nation co-chair position on the physical-sciences working group.

None of the candidates captured a 50 per cent majority in the initial vote, but the second round saw climate modeller Thomas Stocker nominated. “It's certainly the first time that the panel actually had a choice between a slate of different candidates, and in that respect, winning a vote or being given an office is all the more an honour,” says Stocker, head of the climate and environmental physics department of Bern University, Switzerland. He will be joined by Chinese glaciologist Dahe Qin, serving his second term as co-chair of the working group.

The vote on the meeting's other contested co-chair position ended in a dead heat — and reshaped the IPCC's organizational chart. The group on climate mitigation will now be overseen by three experts: economist Ottmar Edenhofer from the Postdam Institute for Climate Impact Research in Germany will have two developing-world co-chairs, Cuban economist Ramon Pichs-Madruga and Youba Sokona, who directs the Sahara and Sahel Observatory, a sustainable-development organization in Mali.

Challenges ahead

Despite the dramatic contest to head the physical-science group, many believe it is the IPCC's work on impacts, adaptation and mitigation that will be most important in the next report.

Some were surprised, however, that Working Group II will be led by two physical scientists — Chris Field and Vicente Barros, a University of Buenos Aires climatologist — rather than by a social scientist or economist. Field, known for his research on carbon cycles, “is very much a natural scientist,” says Colin Prentice, a geoscientist at the University of Bristol, UK. “It's a big change for him.”

“That doesn't mean [Field] can't give good leadership on that side,” says Parry, who worries nonetheless that Working Group II may not be able to make progress on the crucial topic of adaptation options and their costs, simply because research in the area is only now beginning to push ahead. The IPCC's role is to assess current knowledge, Parry points out: “You can't assess knowledge if it's not out there, can you?”

Another challenge facing the new bureau will be how to integrate the work of the three groups. “The issues form a continuum, and it's critical to recognize that many of the most important components of these issues are right at the interfaces between the groups,” says Field.

More critically still, the IPCC now needs to think carefully about how best to serve its purpose of providing information about mitigation and adaptation to those who need it most. This is likely to incorporate more special reports into the panel's remit, says Edenhofer, who adds that they need to “provide scientific, sound information to policymakers in negotiations, but also to decision-makers in business.”