Modern and Holocene fluxes of sediment and organic matter into the Arctic Ocean.
Warming in the Arctic is expected to be roughly twice as high as the global mean. Sea ice extent is declining dramatically over the last years and favors accelerating coastal erosion. With erosion rates as high as 25 m yr-1, the release of organic carbon and nutrients from permafrost coasts has dram...
| Main Authors: | , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2016
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| Online Access: | https://epic.awi.de/id/eprint/41124/ https://epic.awi.de/id/eprint/41124/1/Abstract_ICOP2016_MFritz.pdf https://hdl.handle.net/10013/epic.48134 https://hdl.handle.net/10013/epic.48134.d001 |
| Summary: | Warming in the Arctic is expected to be roughly twice as high as the global mean. Sea ice extent is declining dramatically over the last years and favors accelerating coastal erosion. With erosion rates as high as 25 m yr-1, the release of organic carbon and nutrients from permafrost coasts has dramatic impacts on the global carbon cycle, on nearshore food webs and local communities which are still relying on marine biological resources for food security. During the Holocene, the delivery of sediments, nutrients, particulate organic carbon (POC) and dissolved organic carbon (DOC) varied in response to temperature and relative sea level changes. Phases of increased material input could serve as an analogue for future erosion scenarios. In the past, changing inputs of sediments, carbon, and nutrients may have altered the biogeochemical setting on the upper arctic shelves and may have impacted the global carbon cycle. Recent flux estimates of sediment and POC from coastal erosion into the Arctic Ocean are ~430 Tg yr-1 sediment and 4.9-14 Tg yr-1 POC, which is comparable to if not higher than riverine fluxes (Wegner et al., 2016). However, the fate of sediments and organic carbon once eroded from the cliff remains largely unknown (Stein and Macdonald 2004) and the release of DOC from melting ground ice in permafrost cliffs has not been considered yet (Fritz et al. 2015). Material supply over the Holocene is difficult to quantify as it depends on erosion of a coastline whose original configuration is unknown. For example, large parts of the circum-arctic shelves were subaerially exposed during the last glacial maximum (LGM) and became flooded rapidly. Consequently, erosion of coastal permafrost deposits was probably stronger in the early Holocene than today and released more sediments, nutrients and carbon. In the middle Holocene sediment fluxes in the Laptev Sea for example were more variable than today, partly due to rising sea level, spatially and temporally variable flooding of bathymetric features, and coastline ... |
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