Non-governmental organisations and international organisations with relevant expertise are also invited to review the drafts. The reviewers comment on the completeness and objectivity of the scientific and technical content. References within the draft are carefully checked. When time permits, the review comments are incorporated into a second draft which is sent back to the reviewers. These summaries are reviewed as well.
Governments review the expert-approved chapters and the summaries.
They may organise their own groups of experts to carry out this review. The Government-level review is essential because it promotes and demonstrates a broad, international acceptance of the technical conclusions. As of mid-1993, many more countries and organisations are involved in the earliest stage of the work cycle than was the case with the First Assessment Report. Finally, the summaries of the three Working Groups are reviewed by the entire IPCC and formally accepted. A synthesis report highlighting the key points, including those that may be controversial, is drafted by the IPCC chairman and approved line by line by the entire Panel.