• WG I focuses on the physical science basis and will include 258 experts.
• WG II assesses the impacts, adaptation strategies and vulnerability related to climate change and will involve 302 experts.
• WG III covers mitigation response strategies in an integrated risk and uncertainty framework and its assessments will be carried out by 271 experts.

In March 2010, the IPCC received approximately 3,000 nominations. At the Bureau session held in Geneva, 19-20 May 2010, the three working groups presented their selected authors and review editors for the AR5. Each of the selected scientists, specialists and experts was nominated in accordance with IPCC procedures, by respective national IPCC Focal-Points, by approved observer organizations, or by the Bureau.

The IPCC said that in its selection of authors, it gave particular attention to relevant expertise to ensure that author teams consist of leading experts in the respective fields with a range of scientific views on climate change.

The 831 individuals are drawn from fields including meteorology, physics, oceanography, statistics, engineering, ecology, social sciences and economics. In selecting the author teams the IPCC stressed the need for regional and gender balance and recognized the importance of involving new and younger authors.

In comparison to the Fourth Assessment Report (AR4), participation from developing countries has been increased reflecting the on-going efforts to improve regional coverage in the AR5. About 30% of authors will come from developing countries or economies in transition. The proportion of female experts, has significantly increased since the AR4, reaching approximately 25% of the selected authors. More than 60% of the experts chosen are new to the IPCC process, which will bring in new knowledge and perspectives.

The IPCC received 50% more nominations of experts to participate in AR5 than it did for AR4. A total of 559 authors and review editors had been selected for AR4 from 2,000 proposed nominees.