The last deglaciation: timing the bipolar seesaw

Abstract

Abstract. Precise information on the relative timing of north-south climate variations is a key to resolving questions concerning the mechanisms that force and couple climate changes between the hemispheres. We present a new composite record made from five well-resolved Antarctic ice core records that robustly represents the timing of regional Antarctic climate change during the last deglaciation. Using fast variations in global methane gas concentrations as time markers, the Antarctic composite is directly compared to Greenland ice core records, allowing a detailed mapping of the inter-hemispheric sequence of climate changes. Consistent with prior studies the synchronized records show that warming (and cooling) trends in Antarctica closely match cold (and warm) periods in Greenland on millennial timescales. For the first time, we also identify a sub-millennial component to the inter-hemispheric coupling. Within the Antarctic Cold Reversal the strongest Antarctic cooling occurs during the pronounced northern warmth of the Bølling. Warming then resumes in Antarctica, potentially as early as the Intra-Allerød Cold Period, but with dating uncertainty that could place it as late as the onset of the Younger Dryas stadial. There is little-to-no time lag between climate transitions in Greenland and opposing changes in Antarctica. Our results lend support to fast acting inter-hemispheric coupling mechanisms, including recently proposed bipolar atmospheric teleconnections and/or rapid bipolar ocean teleconnections.

A new bipolar ice core record of volcanism from WAIS Divide and NEEM and implications for climate forcing of the last 2000 years

“…Extending the WAIS Divide volcanic record-which is believed to be annually dated until >15 kyrs BP-will enable links to the various timescales from Antarctica by their volcanic signatures, thus significantly improving existing depth-age scales. Potentially, global-scale events during the last ice age can be detected in both hemispheres providing a means to link the ice ages of Greenland and Antarctica that is independent from the uncertainty inherent in the gas-age/ice-age difference, when using ice core CH 4 records for synchronizing ice cores [Pedro et al, 2011].…”

Synchronizing <sup>10</sup>Be in two varved lake sediment records to IntCal13 <sup>14</sup>C during three grand solar minima

“…Particularly the timing and spatial expression of climate variations can provide valuable information about the underlying driving mechanisms (Czymzik et al, 2016b, c;Lane et al, 2013;Rach et al, 2014). However, timescale uncertainties between different paleoclimate records often inhibit the investigation of such climate variations.…”

Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ<sup>15</sup>N measurements

“…Alternatively, it can be characterized by the depth difference in the ice core record between gas and ice of a given age, noted depth and given in actual physical metres. Constraining the firn structure is crucial to accurately estimate age and depth and reduce uncertainties in ice and gas chronologies, in particular for clarifying the exact timing between CO 2 concentration and Antarctic surface temperature during deglaciations (Fischer et al, 1999;Caillon et al, 2001;Monnin et al, 2001;Pedro et al, 2011;Shakun et al, 2012;Parrenin et al, 2013).…”