The elected chair will hold office for the next five to seven years - a critical period both for the climate and the organisation, with temperatures expected to soon strike 1.5 Celsius of warming above preindustrial levels.

Four candidates, including the first women candidates in the Intergovernmental Panel on Climate Change's (IPCC) 35-year history, are vying for the top job in Nairobi. Dozens of other bureau members will also be appointed.

The IPCC is tasked with creating extensive reports that are considered the most authoritative source of scientific knowledge on climate change. All candidates aim to promote diversity in the body where two-thirds of its scientists are men.


- Jean-Pascal van Ypersele (Belgium), a physicist involved with the IPCC's work as an author and vice-chair since 1995, is running for the top job a second time. A nature lover, he sent an emotional letter to his great-grandchildren about biodiversity loss and released a campaign photo on top of Mont Blanc pledging to "lead the IPCC to new heights".

He advised Fiji's presidency at past U.N. climate talks and has emphasised climate justice. He told Reuters that the IPCC's messages needed to be made more relevant for policy makers.

- Thelma Krug (Brazil), a mathematician who previously led efforts to monitor deforestation in the Amazon, told Reuters she was inspired to run following the election of President Luiz Inacio Lula da Silva who has prioritised the climate change issue.

Krug, who became the first female IPCC vice-chair in 2015, would also be the first Latin American chair. She told Reuters she has overcome career challenges like financing her degree while raising a child. If elected, she would seek to boost regional representation and promote science in languages other than English.

- Debra Roberts (South Africa), a natural scientist and the current co-chair of the IPCC group on climate change's impacts, is one of two female candidates.

She has just been endorsed by the African Union and, if elected, would be the first African chair. Her extensive practical experience including in urban reforestation could be an advantage, analysts say, especially since the body will soon produce a report on cities. The IPCC's upcoming work "can inform more real-world decisions than ever before," she told Reuters.

- Jim Skea (United Kingdom), a sustainable energy professor who co-chaired the IPCC's work on mitigating climate change, started with the IPCC 30 years ago. "I think I know how to pull the strings to make things happen," he said.

Skea said it was important for future reports to address overshoot scenarios -- how to prepare and respond to a situation where the Paris deal warming limits are surpassed and to explore all options for mitigation through technology. He heads Scotland's Just Transition commission and stresses his track record on forging consensus in negotiations.


Created by two U.N. bodies in 1988, the IPCC produces objective and comprehensive reports considered the most authoritative source of scientific knowledge on climate change.

They come from three so-called working groups covering the science of climate change, its impacts and ways to mitigate them. With these elections, it will now enter the seventh series of such assessments.

The IPCC chair together with the bureau has the potential to shape the research agenda which often include additional special reports on specific subjects. For example, the current chair Hoesung Lee has brought into focus climate change solutions since he began in 2015.

The chair needs a rare combination of scientific and diplomatic skills, especially for winning government approval for report summaries.

The reports inform international climate talks such as the annual U.N. climate summits, the so-called COP meetings.


The chair's election is closed-door and via secret ballot. A simple majority is needed and if none is obtained in round one the top two candidates compete in a further round.

All 195 member states have a vote and the results are expected on Wednesday or Thursday.

(Reporting by Emma Farge, Jake Spring, Kate Abnett and Gloria Dickie; Editing by Janet Lawrence and Angus MacSwan)