A jökulhlaup from a Laurentian captured ice shelf to the Gulf of Mexico could have caused the Bølling warming

U. Erlingsson


Abstract

Since the rapid rate of the global warming at the onset of Bølling became evident, its cause has been under debate. It coincides closely in time with a strong global transgression called meltwater pulse 1a (mwp-1a). One attempt of solution says that an mwp-1a of Antarctic origin could cause an increase in North Atlantic Deep Water (NADW) formation, and thus give rise to the Bølling interstadial. However, others have disputed that Antarctic meltwater would have that effect, and furthermore, the start of Bølling is not even associated with an increase in NADW. A controversial hypothesis says that some Laurentian meltwater came from a sub-glacial jökulhlaup, but no study yet has shown unequivocally that sufficient amounts of water could be stored under the ice. Furthermore, according to all available data a meltwater pulse from the Laurentian ice gives rise to strong cooling, not warming. Nevertheless, megafloods appear instrumental in accumulating the Mississippi Fan, created entirely during the Quaternary period, and dramatic climate changes are characteristic of our period. This paper presents an hypothetical chain of events, building on the published literature and simple calculations to see if the order of magnitude is reasonable. The hypothesis is that a jökulhlaup from a Laurentian captured ice shelf (CIS) flowed out through the Mississippi, boosted the Gulf Stream, reinvigorated the North Atlantic circulation, and as a result triggered the Bølling warm phase.
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