Understanding the Arctic marine carbon cycle under changing climate: a reconstruction of productivity and biogenic carbon burial on the West Greenland margin of the Baffin Bay

Abstract

The continued input of additional carbon dioxide (CO2) since the start of the Industrial Revolution has increased the atmospheric CO2 content and the uptake of atmospheric CO2 by the ocean, which changes marine chemistry. These changes will trigger shifts in biological productivity and ecosystem processes, with the Arctic realm being expected to experience a greater-than-average response with profound effects on the marine carbon cycle. Models projecting future changes in the behaviour of the marine carbon cycle demand sustainable constraints. The geological record provides an opportunity to provide observational constraints by assessing past interactions between changing climate conditions and the marine carbon cycle. In the Baffin Bay, the Holocene may serve as an example to estimate the direction and magnitude of possible future developments and as an equivalent for the recent environmental changes. The aim is to contribute to the understanding of the marine carbon cycle as a requirement for the provisioning of sustainable model constraints by quantifying its key drivers like primary productivity (pp), export productivity and carbon burial. The establishment of a method for a nuisance free quantification of past pp is a prerequisite, at it is mostly influenced by other signals induced by diagenetic processes or other parameters obliterating the signal of pp. With the potential of an adequate quantification of pp, the sensitivity of key components driving the marine carbon cycle to changing environmental boundary conditions is evaluated. Results imply that during meltwater-influenced warming conditions the efficiency of organic carbon burial is decreasing, resulting in a weakening of the organic carbon pump. This is probably caused by changes in export efficiency, induced by a combination of an increase in the efficiency of organic matter recycling in the productive zone and a decrease in preservation due to longer oxygen exposure times induced by lower sedimentation rates.