Kalt erwischt - Caught with the sea levels down: The effect of glacial sea levels on carbon release from shelf sediments

Abstract:

Glacial to interglacial sea level change has a long term effect on the width of continental shelves (0-200m water depth) and on geochemical processes inside shelf sediments that are periodically drained and inundated during glacial cycles. In our current interglacial situation, the global shelf area is 27 million km² compared to 8 million km² under fully glacial conditions, where more than 80% of the previously inundated area gets drained. The change between inundation and drainage of the shelves not only allows or blocks ambient air access to sediments within the drainable range of the shelf wedge, but it also has long-range effects on the terrestrial water tables and both, terrestrial and shelf erosion patterns. We use a forward model driven by sea level change to assess the effect of inundation and drainage on carbon release from shelves and on global CO₂ levels. We identify a previously unrecognized mechanism that may cause global scale CO₂ release in low sea level situations. This mechanism is consistent with the "mystery interval" addition of ∂¹⁴C depleted carbon around 14.6 ka and it might explain the steep late glacial rise in CO₂ that seems to be very hard to model with the current constraints.