Understanding terrestrial carbon processes is a major challenge in climate science. We define the satellite system required to understand greenhouse gas biogeochemistry: our study is focused on Amazon wetland CH₄ emissions. We find that future geostationary satellites will provide the CH₄ measurements required to understand wetland CH₄ processes. Low-earth orbit satellites will be unable to resolve wetland CH₄ processes due to a low number of cloud-free CH₄ measurements over the Amazon basin.