As part of the Expert Review Teams, there are two experienced experts who act as co-lead reviewers during the review. One co-lead reviewer is selected from an Annex I Party and one from a non-Annex I Party. Lead reviewers ensure that the reviews in which they participate are performed by each ERT according to the relevant review guidelines and are implemented consistently across Parties. They also ensure the quality and objectivity of the thorough and comprehensive technical examinations in the reviews and provide for the continuity, comparability and timeliness of the reviews.

The secretariat facilitates annual meetings of lead reviewers for GHG inventories, BRs and NCs in accordance decision 23/CP.19 and its annex. These meetings provide an important opportunity to harness the LRs experience in undertaking reviews to help improve the quality, efficiency and consistency of the reviews, including through the preparation of a Review Practice Guidance.