Carbon storage in important unprotected sites
We used the following procedure to estimate the carbon storage in unprotected sites that are important for biodiversity. Firstly, carbon storage in unprotected IBAs was estimated based on the unprotected area of IBAs multiplied by the mean carbon density for all IBAs. Secondly, we extrapolated carbon storage to unprotected KBAs by assuming that KBAs have the same carbon density as IBAs. Thirdly, we extrapolated to include those countries not having IBAs (excluding Antarctica) by assuming that unprotected IBAs/KBAs have the same carbon density as protected areas in these countries.