Land and soil
Soil organic carbon
Soil organic carbon is carbon held in soil as decayed plant and animal matter. It drives how well soil holds water and nutrients, and it is one of the largest carbon stores on land. Ploughing and clearing release it. Cover and roots rebuild it, slowly.
Measuring it properly means taking samples at consistent depth and analysing them in a laboratory, which is slow and unglamorous next to satellite imagery.
It also moves slowly enough that annual claims about it should be treated with suspicion.