Destabilization of carbon in tropical peatlands by enhanced weathering

Enhanced weathering is a carbon dioxide (CO2) removal strategy that accelerates the CO2 uptake and removal from the atmosphere by weathering via the dispersion of rock powder. Warm and humid conditions enhance weathering and among the suggested target areas for enhanced weathering are tropical peatlands. However, the effect of enhanced weathering on peatland carbon stocks is poorly understood. Here, we present estimates for the response of CO2 emissions from tropical peat soils, rivers and coastal waters to changing soil acidity induced by enhanced weathering application. We estimate that the potential carbon uptake associated with enhanced weathering is reduced by 18-60% by land-based re-emission of CO2 and is potentially offset completely by emissions from coastal waters. Our findings suggest that in contrast to the desired impact, enhanced weathering may destabilize the natural carbon cycle in tropical peatlands that act as important carbon sinks and protect against coastal erosion. Enhanced weathering in tropical peatlands may be an ineffective carbon dioxide removal strategy due to pH-induced increases in soil carbon leaching which lead to increased re-emission of carbon, according to model calculations constrained by observations from Sumatra, Indonesia.

Automated summary

Enhanced weathering is a strategy to remove carbon dioxide quickly, but its application in tropical peatlands may have negative consequences. Studies have shown that enhanced weathering might lead to carbon re-emission from soil and could potentially be offset by emissions from coastal waters.