Surge of peatland destruction by an advancing front of artisanal gold mining in Amazonia

Abstract

Alluvial sediments bordering rivers of the southern Peruvian Amazon are enriched with gold, which has sustained an artisanal gold mining economy within a biodiversity hotspot for the past several decades. While it is clear that sweeping deforestation by miners has resulted in substantial loss of above-ground carbon stocks and increased greenhouse emissions, the region also harbors a sizable below-ground carbon stock in the form of peatlands, and how these have fared against decades of mining expansion is uncertain. Here, we use Landsat's continuous archival record spanning over 35 years to monitor the expansion of gold mining in a major Amazonian peat complex along the alluvial plain of the Madre de Dios River. We detect over 550 ha of peatland surface area that has been lost to gold mining, potentially accounting for between 0.2 and 0.7 Tg of emitted below-ground carbon. Alarmingly, the majority of this loss (55%) has occurred within the past two years. Mining inside peatlands currently accounts for 9% of total mining, but projections suggest a 25% share by 2027 as mining within peatland is accelerating considerably faster than mining in the alluvial plain as a whole. The startling surge of peatland degradation is synchronous with the arrival of an aggressive mining front into the most distal reaches of the alluvial plain where peatlands are most abundant. Already, 63 of 219 peatlands in the alluvial plain show evidence of mining within their borders, putting over 10 000 ha of peatland area and between 3.5 and 14.5 TgC at imminent risk. The rapid proliferation of gold mining inside peatlands appears to be of such scope as to be an existential threat to the entire peatland complex.