Carbon burial in subpolar fjords - a missing global carbon sink?

Carbon burial and sequestration in the oceans are very important issues in understanding global climate controls and are necessary to provide more accurate future climate models. One of potential important sinks are subpolar... [ view full abstract ]

Carbon burial and sequestration in the oceans are very important issues in understanding global climate controls and are necessary to provide more accurate future climate models. One of potential important sinks are subpolar fjords, which are particularly sensitive to global climate changes as proved by modern monitoring data and the past records. One of the most spectacular changes is the rapid retreat of tidewater glaciers during the post-Little Ice Age period (after ~1900) observed in many subpolar fjords of European Arctic. The goal of this study is to assess if the observed climatic changes affected sediment accumulation and carbon burial rates in selected fjords of Svalbard. The study reviews the existing data and new results on 210Pb and 137Cs based accumulation rates, as well as organic carbon content from Hornsund, Tempelfjorden and Kongsfjorden - the major fjords of western Spitsbergen. In the central parts of the fjords the sediment accumulation rates are generally in the order of several mm per year and in most cases significantly increased after the Little Ice Age. Consequently, also the carbon burial rates have increased. Moreover, due to the retreat, new bays often with area of several km2 each and characterised by very high sediment accumulation rates (several cm/year) have been formed in the inner parts of the fjords. They appear to store exceptionally large amounts of sediment and carbon, mainly of terrestrial origin. The available data suggest that this kind of fjords may serve as significant carbon sinks on global scale.
The study was funded by Polish National Science Centre grant No. 2013/10/E/ST10/00166.