Structural basin

Geology

Archaeology

Greenhouse gas

Biology

Physical geography

Geomorphology

Oceanography

Geography

Subsidence

Geotechnical engineering

Ecology

Earth science

Programming language

Deforestation (computer science)

Computer science

Land use

Hydrology (agriculture)

Environmental science

Peat

Nature Geoscience

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. Subsidence and carbon emissions in tropical peatlands are primarily linked to drainage history, not land-use type, according to large-scale high-resolution remote sensing in Southeast Asia.

Widespread subsidence and carbon emissions across Southeast Asian peatlands