Soil organic carbon dust emission: an omitted global source of atmospheric CO2

TitleSoil organic carbon dust emission: an omitted global source of atmospheric CO2
Publication TypeJournal Article
Year of Publication2013
AuthorsChappell A, Webb N, Butler H, Strong CL, McTainish G, Leys J, Rossel RAViscarr
JournalGlobal Change Biology
Start Page3238
Date Published07/2013
ARIS Log Number295947
KeywordsAustralia, carbon accounting, carbon budgets, carbon dioxide, dust emission, soil organic carbon

Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO2) budget because wind erosion contributes to the C cycle by removing selectively SOC from vast areas and transporting C dust quickly offshore; augmenting the net loss of C from terrestrial systems. However, the contribution of wind erosion to rates of C release and sequestration is poorly understood. Here we describe how SOC dust emission is omitted from national C accounting, is a neglected source of CO2 and a likely accelerant of SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO2 emission. We developed a first approximation to SOC enrichment for a well-established dust emission model and quantified SOC dust emission for Australia (5.83 Tg CO2-e y-1) and Australian agricultural soils (0.4 Tg CO2-e y-1). These amount to under-estimates for CO2 emissions of ~10% from combined C pools in Australia (yr=2000), ~5% from Australian Rangelands and ~3% of Australian Agricultural Soils by Kyoto Accounting. Northern hemisphere countries with greater dust emission than Australia are also likely to have much larger SOC dust emission. Therefore, omission of SOC dust emission likely represents a considerable underestimate from those nations’ C accounts. We suggest that the omission of SOC dust emission from C cycling and C accounting is a significant source of uncertainty. Tracing the fate of wind-eroded SOC in the dust cycle is therefore essential to quantifying the release of CO2 from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks.