Various methods are used to track adaptation finance, which makes comparisons between adaptation finance figures challenging . For example, multi-lateral development banks use a different methodology than countries do under the OECD Development Assistance Committee  . One of the differences concerns the treatment of partially adaptation-relevant projects, namely whether only parts or the full amount of a given project volume are counted as adaptation finance . Under the OECD DAC methodology, countries often use a fixed percentage , whereas the MDB methodology attempts for a project-specific estimation of the adaptation-relevant proportion . Another aspect is whether tracking distinguishes between financial instruments, such as grants or loans. Different accounting rules can lead to large differences in reported amounts of adaptation finance and to a lack of comparability between providers . Studies identified an over-reporting  by a factor of two to three, which suggests the need for a more consistent and transparent accounting system .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report