Is there a causal link between sea level, permafrost zone advances and Pleistocene climate evolution?

Abstract

Since Milanković postulated casual links between orbitaly controlled insolation change sand (Pleistocene) climate dynamics, the global palaeoclimate community has made significant progress in the understanding the numerous important patterns and shifts in late Cenozoic climate variation. However, the cause of events such as the middle Pleistocene transition, the mid Brunhes event, and changes in the expression of interglacials over time remain largely enigmatic.A potential answer to some of these unsolved questions maybe related to Plio-Pleistocene environmental evolution in the Arctic Ocean. This highly sensitive region maybe regarded as a key driver of global climate because of variations in the form, intensity and permanence of sea ice cover, which have a profound impact on
the Earth’s albedo, permafrost distribution and global thermohaline circulation. Yet the potential impact of the Arctic Ocean remains poorly understood. Due to the specific morphology of the Arctic Ocean floor, changes in sea-level can have a dramatic effect on the palaeogeography and circulation in the region. Notably only a modest 50m sea-level falls required to cut-off exchange with the Pacific through the Bering Strait,while many of the surrounding shelves have relatively shallow mean depths, for example the Laptev (48 m), East Siberian (58 m), Chukchi (80 m) and Beaufort (124 m) Seas. This implies that the Bering Strait could have been closed and much of the surrounding shelves exposed during frequent Pleistocene low stands. These are regions where the majority of sea-ice isformed today and surrounding exposed areas are associated with vast permafrost zones. More frequent flooding and subsequent exposure of the Arctic continental shelves would be associated with an alternationofthe extent of the permafost zone. These zones provide suitable conditions forsignificant storage of CO2 in large parts of the Northern Hemisphere. We propose that these processes operating during the Marine Isotope Stages(MIS) 5, 7 and 9 limited “full” interglacial conditions to just MIS 5.5, MIS 7.5 and MIS 9.5.

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Bibliography

Markovic, S., Zech, R., Stevens, T., Gavrilov, M., Zeeden, C. (2014): Is there a causal link between sea level, permafrost zone advances and Pleistocene climate evolution?. Milankovitch Anniversary UNESCO Symposium, 3.-5.9.2014, Belgrade, Serbia.