Meltwater pulse 1A

[1][3] Meltwater pulse 1A occurred in a period of rising sea level and rapid climate change at the end of the last ice age, known as Termination I.

[3] The start of this meltwater event coincides with or closely follows the abrupt onset of the Bølling-Allerød (B-A) interstadial and warming in the NorthGRIP ice core in Greenland at 14,600 years ago.

If the eustatic sea level rise was large and closer to 20 meters (66 ft) than the lower estimates, a significant fraction of the meltwater that caused it likely came from the Antarctic Ice Sheet.

[11][12] A contribution of around 2 meters (6.6 ft) in 350 years to meltwater pulse 1A from the Antarctic Ice Sheet could have been caused by Southern Ocean warming.

[13] With respect to the Antarctic Ice Sheet, research by Weber and others constructed a well-dated, high-resolution record of the discharge of icebergs from various parts of the Antarctic Ice Sheet for the past 20,000 years, They constructed this record from variations in the amount of iceberg-rafted debris versus time and other environmental proxies in two cores taken from the ocean bottom within Iceberg Alley of the Weddell Sea.

[21][22] In the case of the Mississippi River, the sediments of the Louisiana continental shelf and slope, including the Orca Basin, within the Gulf of Mexico preserve a variety of paleoclimate and paleohydrologic proxies.

[26][27][28] The chronology of flooding events found by the study of numerous cores on the Louisiana continental shelf and slope are in agreement that the timing of meltwater pulses.

In addition, meltwater pulse 1B in the Barbados coral record matches a cluster of four Mississippi River superflood events, MWF-5, that occurred between 9,900 and 9,100 RCYBP.

This research also shows that the Mississippi meltwater flood MWF-4 occurred during the Allerød oscillation and had largely stopped before the beginning of the Younger Dryas stadial.

[27] Although the Eurasian Ice Sheet has previously been considered an insignificant, negligible contributor to meltwater pulse 1A, some research suggests it may have contributed to around half of the sea level rise.