Over the last three decades, most of the 25 million hectares of tropical peatlands in Southeast Asia have been deforested and drained. As a consequence, declining water tables are exposing peat to oxidation, converting plant material accumulated over millennia to carbon dioxide, and causing land subsidence. Here, we quantify the widespread peat carbon loss by using InSAR remote sensing to map subsidence at 90-m resolution across 2.7 Mha of peatland area from 2007 to 2011. Over 90% of the surveyed area is subsiding, with a mean rate of 2.2 cm yr⁻¹. Consequently, the region now faces loss of productive land and flooding because many peatlands are near sea level. Our measurements reveal that smallholder agricultural areas and degraded peatlands are subsiding at rates comparable to those of plantations, and that subsidence rates increase away from rivers and decrease over time following drainage. Because of its detailed spatial resolution, InSAR provides a valuable tool to identify emissions by land use and geography and to target hotspots for better management. Finally, we use remotely sensed maps to update IPCC emissions factors and calculate regional CO₂ emissions from peat oxidation of 155 ± 30 MtC yr⁻¹ in 2015, similar in magnitude to both regional fossil-fuel emissions and peat fires.

在过去的三十年中，东南亚2500万公顷的热带泥炭地中的大部分已经被砍伐和排水。结果，地下水位下降使泥炭遭受氧化，将数千年来积累的植物材料转化为二氧化碳，并导致地面沉降。在这里，我们通过使用InSAR遥感技术在2007年至2011年的2.7 Mha泥炭地面积上以90 m分辨率的沉降图来量化广泛的泥炭碳损失。超过90％的被调查面积正在沉降，平均速率为2.2 cm yr ^-1。因此，由于许多泥炭地都在海平面附近，该地区现在正面临生产用地和洪灾的损失。我们的测量结果表明，小农农业区和退化的泥炭地正在以与人工林相当的速率沉降，并且沉降速率随着远离河流而增加，并随着排水而逐渐降低。由于其详细的空间分辨率，InSAR提供了一种有价值的工具，可通过土地使用和地理位置来识别排放量，并针对热点地区进行更好的管理。最后，我们使用遥感地图更新IPCC排放因子，并计算2015年泥炭氧化产生的区域CO ₂排放为155±30 MtC yr ^-1，其幅度与区域化石燃料排放和泥炭火灾相似。