AMOC and bi-polar seesaw

Menviel et al., 2011

Older dryas cooling in the NH due to meltwater from Laurentide and Antarctica ice sheet

boiling warming (15kaBP) - due to rapid resurgence of the AMOC through the bipolar seesaw

YD - AMOC shut down due to fresh water from Arctic region

Bipolar seesaw - anti-correlation between temperature and precipitation between hemispheres

buizert et al., 2014

deglaciation due to changes to insolation and redistribution of heat by the AMOC

increase in strength of AMOC = NA warming = reduction in sea ice cover

McManus et al., 2004

changes to AMOC evidenced in marine core chemical composition

AMOC disappeared during coldest de-glacial due to ice berg discharge from first Heinrich event

abrupt decline before the YD

acceleration after these events = rapid warming

AMOC = significant forcer in abrupt climate change

Muschitiello et al., 2019

400 year lag between changes to NADW and abrupt changes to climate - evidenced by Greenland ice cores (temperature and freshwater input)

AMOC redistributes heat near the surface of the Atlantic Ocean and the storage of carbon in deep water

issues = lack of high resolution proxies in deep convection sites and issue of reservoir ages

Broecker, 1998

firs proposed the bipolar seesaw effect - changes in the AMOC manifest in the opposite effect in the SH

bi-polar seesaw in the amount of heat released from ocean circulation

has occurred during the period of deglaciation

Sowers and Bender, 1995

during the YD - the Antarctic was in a period of maximum warming (evidenced by stable oxygen isotope analysis)

Thomas and Fedorov, 2019

future climatic models predict that the AMOC will weaken throughout the century

created a model to identify and explain oceanic mechanisms which can lean to a partial recovery of the AMOC - gradual subsurface changes to ocean properties which reduces the vertical density gradient = partial reinvigoration of deep water formation

requires that there is limited climate change forcing

Pedro et al., 2018

bipolar seesaw - simplest model to explain the temporal relationship between D-O events and AIM events

changes in heat transport of the Atlantic are slightly counteracted by changes in heat transport within the global atmosphere and Pacific Ocean

heat reservoir causing this coupling is located in the Antarctic circumpolar current

Antarctic warming given by increased poleward atmospheric heat and moisture transport

delay is due to the time needed fro heat to accumulate in the ocean interior

Landais et al., 2015

progress in formation of chronologies = able to compare Greenland and Antarctica to within a few centuries

see-saw pattern doesn’t not explain the regional variability found in Antarctic records - suggestive of additional teleconnections between low latitude atmospheric circulation and Antarctica without input from Greenland

Blunier et al., 1998

aligned Byrd core and GRIPD based off of CH4 records spanning the last 90kabP

identification of 7 antarctic warm events - during each of these as antarctic temperature warmed gradually during Greenland stadia conditions, when warming in Antarctica stoped it started in Greenland

unclear if glacial calving is due to changes to AMOC or causes the changes itself

mostly agreed that Greenland warming is due to freshwater from North America due to the complexity of the southern ocean