Holocene glacier behavior around the northern Antarctic Peninsula and possible causes

KAPLAN, M.R.; STRELIN, J.A.; SCHAEFER, J.M.; PELTIER, C.; MARTINI, M.A.; FLORES, E.; WINCKLER, G.; SCHWARTZ, R.

EARTH AND PLANETARY SCIENCE LETTERS

ELSEVIER SCIENCE BV

Año: 2020 vol. 534

0012-821X

 We obtained 49 new 10Be ages that document theactivity of the former Northern Antarctic Peninsula Ice Sheet, and subsequentlythe James Ross Island Ice Cap and nearby glaciers, from the end of the lastglacial period until the last ∼100 years. The data indicate that from >11 to ∼8 ka marked recession of glacier systems occurredaround James Ross Island, including tidewater and local land-terminatingglaciers. Glaciers reached heads of bays and fjords by 8-7 ka. Subsequently,local glaciers were larger than present around (at least) 7.5-7 ka and ∼5-4 ka, at times between 3.9 and 3.6 ka and just after3 ka, between ∼2.4 and ∼1 ka, and from ∼300 to ∼100 years ago. After deglaciation, the largest localglacier extents occurred between ∼7 ka and ∼4 ka.Comparisonwith other paleoclimate records, including of sea ice extent, reveals coherentclimate changes over ∼15◦of latitude. In the early Holocene,most of the time a swath of warmth spanned from southern South America to theAntarctic Peninsula sector. We infer such intervals are times of weakeningand/or poleward expansion of the band of stronger westerlies, associated withcontraction of the polar vortex. Conversely, increased sea ice and equatorwardexpansion of the westerlies and the polar vortex favor larger glaciers fromPatagonia to the Antarctic Peninsula, which typically occurred after ∼8 ka, although warm stretches did take place. For example, on theAntarctic Peninsula and in Patagonia the interval from 4 to ∼3 ka was typically warm, but conditions were not uniform in eitherregion. We also infer that reduced and expanded glacier extents in Patagoniaand the eastern Antarctic Peninsula tend to occur when conditions resemble apersistent positive and negative southern annular mode, respectively.