A new sea-level record for the Neogene/Quaternary boundary reveals transition to a more stable East Antarctic Ice Sheet

Abstract

Sea-level rise resulting from the instability of polar continental ice sheets represents a major socioeconomic hazard arising from anthropogenic warming, but the response of the largest component of Earth’s cryosphere, the East Antarctic Ice Sheet (EAIS), to global warming is poorly understood. Here we present a detailed record of North Atlantic deep-ocean temperature, global sea-level, and ice-volume change for ∼2.75 to 2.4 Ma ago, when atmospheric partial pressure of carbon dioxide (pCO2) ranged from present-day (>400 parts per million volume, ppmv) to preindustrial (<280 ppmv) values. Our data reveal clear glacial–interglacial cycles in global ice volume and sea level largely driven by the growth and decay of ice sheets in the Northern Hemisphere. Yet, sea-level values during Marine Isotope Stage (MIS) 101 (∼2.55 Ma) also signal substantial melting of the EAIS, and peak sea levels during MIS G7 (∼2.75 Ma) and, perhaps, MIS G1 (∼2.63 Ma) are also suggestive of EAIS instability. During the succeeding glacial–interglacial cycles (MIS 100 to 95), sea levels were distinctly lower than before, strongly suggesting a link between greater stability of the EAIS and increased land-ice volumes in the Northern Hemisphere. We propose that lower sea levels driven by ice-sheet growth in the Northern Hemisphere decreased EAIS susceptibility to ocean melting. Our findings have implications for future EAIS vulnerability to a rapidly warming world.

Abrupt climate changes and the astronomical theory: are they related?

“…The third date, close to the MIS22-24 δ 18 O optima, shows increased continental ice volume in the Northern Hemisphere (Batchelor et al, 2019) but also more stability in the East Antarctic ice sheet in Southern Hemisphere (Jakob et al, 2020). In parallel, evidence of a major glacial pulse recorded in Italy's Po Plain, as well as in 10 Be-dated boulders in Switzerland, is interpreted as marking the onset of the first major glaciation in the Alps (Muttoni et al, 2003;Knudsen et al, 2020).…”

Influence of the choice of insolation forcing on the results of a conceptual glacial cycle model

“…Other effects like thermal expansion, small glaciers and ice caps are estimated to be around 3 to 4 m sea level equivalent. Furthermore, it has been suggested (Jakob et al, 2020) that the growth of larger Northern Hemisphere ice sheets since the start of the Quaternary and the associated sea level drop has a stabilizing effect on the East Antarctic ice sheet, as it limits its exposure to warm ocean waters.…”

Stable Biological Production in the Eastern Equatorial Pacific Across the Plio‐Pleistocene Transition (∼3.35–2.0 Ma)

“…The final phase of iNHG (MIS 100–96) is also clearly expressed in our data set by (i) an increase in glacial δ 18 O values from on average ∼3.8‰ (MIS M2–102) to ∼4.4‰ (MIS 100–96) and (ii) amplified glacial‐interglacial variations. Both marine and terrestrial geological records indicate that during these prominent glacials of the iNHG sea level dropped to ∼40–70 m below modern (de Boer et al., 2014; Jakob et al., 2020), the Laurentide Ice Sheet advanced into the mid‐latitudes, and large‐scale ice rafting occurred across the North Atlantic Ocean for the first time (Bailey et al., 2010; Balco & Rovey, 2010; Shackleton et al., 1984). In our record, the high δ 18 O values of glacials MIS 100–96 are reached again during glacials MIS 82 and 78.…”