Thursday, December 26, 2013

New paper finds globe was warmer, sea levels rose faster & higher during the last interglacial

A paper published today in the Journal of Quaternary Science notes that during the last interglacial, "global temperatures were 2 °C higher and rates of sea-level rise [greater than 5.6mm/year], leading to sea levels 6.6–9.4 meters [22 to 31 feet] higher than present. The source(s) of this sea-level rise remain fiercely debated."

Thus, during the last interglacial, the globe was naturally 2 °C warmer, sea levels rose 5 times faster than at the presentsea levels were up to 31 feet higher than the present, and Antarctic sea ice was much less than the present, all with "safe" levels of CO2. There is no evidence that climate change within the present interglacial is any different, unprecedented, unnatural, unusual, or due to man-made CO2.

Testing the sensitivity of the East Antarctic Ice Sheet to Southern Ocean dynamics: past changes and future implications 


The stability of Antarctic ice sheets and their potential contribution to sea level under projected future warming remains highly uncertain. The Last Interglacial (135,000–116,000 years ago) provides a potential analogue, with global temperatures 2 °C higher and rates of sea-level rise >5.6 m ka−1, leading to sea levels 6.6–9.4 m higher than present. The source(s) of this sea-level rise remain fiercely debated. Here we report a series of independent model simulations exploring the effects of migrating Southern Hemisphere Westerlies (SHWs) on Southern Ocean circulation and Antarctic ice-sheet dynamics. We suggest that southerly shifts in winds may have significantly impacted the sub-polar gyres, inducing pervasive warming (0.2–0.8 °C in the upper 1200 m) adjacent to sectors of the East Antarctic Ice Sheet (EAIS), which due to their geometries and connectivity to the Southern Ocean are highly sensitive to ocean forcing. We conclude that the EAIS potentially made a substantial, hitherto unsuspected, contribution to interglacial sea levels, and given 21st-century projections in the Southern Annular Mode and associated SHW migration, we highlight how pervasive circum-Antarctic warming may threaten EAIS stability.

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