Three Arctic seas hold vast carbon reserves—but rapid warming puts them at risk
Scientists have pinpointed the Baltic, Barents, and Chukchi Seas as the Arctic's dominant carbon storage hotspots, disproportionately important for global climate regulation. As these regions warm faster than anywhere on Earth, disruptions to river flows and ocean currents threaten to unlock sequestered carbon—a tipping point with implications for climate modeling, insurance markets, and Arctic resource planning.
Originaltitel: Hotspots of Arctic and sub-Arctic marine sediment organic carbon are dominated by the Baltic, Barents and Chukchi Seas
Baltiska havet, Barentshavet och Tjuktjerhavet utgör de dominerande kohlagerungarna i höga breddgrader — och båda är exponerade mot Arctic amplification-effekten. En ny analys av över 13 000 sedimentprover identifierar dessa tre havsområden som disproportionellt betydande för det globala marina kvävelagret per ytenhet, med särskilt höga ackumuleringstakter längs grunt kontinentalhyller och kustzoner nära arktiska älvar. Kollagringen beror på samspelet mellan salthalt, blandningsdjup, primärproduktion och sedimentation — processer som förändras snabbt i en varmare Arktis. Bara 10,2 procent av sedimenterna ligger inom marina skyddade områden, vilket betyder att över 17 petagram kollagring står utan institutionellt skydd mot framtida störningar. För infrastrukturplanerare och energiinvesterare blir osäkerheten omkring framtida fluvial transporthastigheter och marina kolcykler en växande riskfaktor för stabiliteten i dessa lagringssystem. Planering bör faktorisera denna sårbarhet redan nu.
Abstract The Arctic and sub-Arctic are warming at least three times faster than the global average, altering terrestrial carbon delivery to the oceans and marine carbon cycling. The sequestration of such carbon into marine sediments is a key contributor to climate regulation. Despite this, the location of organic carbon hotspots at high latitudes are poorly understood, hindering our ability to identify their sensitivity to environmental change. Using quantile regression forests with >13,000 sediment samples, we identify the Baltic, Barents and Chukchi Seas as the dominant high-latitude marine organic carbon hotspots, playing a disproportionately large role in the area-normalised global sedimentary carbon stock. Organic carbon accumulation rates are elevated across shallow shelf environments and coastlines, particularly in proximity to Arctic rivers. Development of organic carbon hotspots reflects both local and external processes, including salinity, mixed layer depth, primary production and sedimentation, demonstrating the importance of coupled land-ocean processes. Uncertainty in future changes to organic carbon cycling and transit pathways, including river transport, is therefore an emerging risk factor for the stability of marine sediment carbon stores. Compounding this, only 10.19% of the surface sediment organic carbon stock is currently within marine protected areas, placing >17 Pg at higher risk of anthropogenic disturbance.