Peatlands are among the largest carbon (C) sinks on the planet. However, peatland features such as open-water pools emit more C than they accumulate because of higher decomposition than production. With this study, we show that the rates of decomposition vary among pools and are mostly driven by the environmental conditions in pools rather than by the nature of the material being decomposed. This means that changes in pool number or size may modify the capacity of peatlands to accumulate C.