Peatland drainage causes over 3.5 % of global anthropogenic GHG emissions, with ~75 % from warm climates. This study examines a drained and partially rewetted warm-climate wetland. Over 66 years, drainage caused ~70 % loss of soil organic matter and substantial CO₂ emissions. Rewetting, initiating ~30 years ago, helped preserve organic matter. Yet, long-term data and modeling shows a limited window for its effectiveness, highlighting the need to prioritize sites based on time since drainage.