Transformations of landscape and peat‐forming ecosystems in response to late Holocene climate change in the western Antarctic Peninsula

Abstract

We used subfossil mosses and peats to document changes in regional climate, cryosphere, and terrestrial ecosystems in the western Antarctic Peninsula at ~65°S latitude. We find that most peat forming ecosystems have initiated since 2800 cal B.P., in response to warmer summers and increasing summer insolation. The period at 900–600 cal B.P. was coldest as indicated by ice advance, abundance of kill ages from ice‐entombed mosses exposed recently from retreating glacial ice, and apparent gap in peatbank initiation. Furthermore, the discovery of a novel Antarctic hairgrass (Deschampsia antarctica) peatland at 2300–1200 cal B.P. from the mainland Antarctic Peninsula suggests a much warmer climate than the present. A warming and wetting climate in the 1980s caused very high carbon accumulation in a Polytrichum strictum moss peatbank. Our results document dramatic transformations of landscape and ecosystems in response to past warmer climate, providing a telltale sign for what may come in the future.

Cirque Glacier on South Georgia Shows Centennial Variability over the Last 7000 Years

“…This coincides with cirque glacier retreat in neighboring Husvik (Figure 2A), as demonstrated by Rosqvist and Schuber (2003) (Figure 11C) and higher temperatures at the western Antarctic Peninsula inferred from changes in peat growth (Yu et al, 2016).…”

“…The shift to a cool and wet climate around 2700 cal BP also falls in line with evidence of a major glacier advance prior to 2600 cal BP in the south-central Andes (Grosjean et al, 1998). On James Ross Island, temperatures starts to decrease after 3000 cal BP (Mulvaney et al, 2012; Figure 11F), while evidence of peat growth initiation since 2800 cal BP suggests warmer summers in the western Antarctic Peninsula (Yu et al, 2016), demonstrating the Antarctic dipole (Yuan, 2004). Figures 6A, Figure 11A).…”

Regional Climate Change Recorded in Moss Oxygen and Carbon Isotopes from a Late Holocene Peat Archive in the Western Antarctic Peninsula

“…Other proxies from terrestrial records support this interpretation, including the increase in peat carbon accumulation and high biological activity [19,23,42]. There was up to 6 • C warmer conditions evidenced by the record of a Deschampsia bog peat found at 65 • S near Cape Rasmussen [21]. This would be best explained by a climate system where warm, moist air was delivered to the AP, and it is likely that a low-pressure system over the Amundsen-Bellingshausen Seas had been dominant during this time [4].…”

“…There is robust evidence that this wet and warm climate was widespread in the Southern Hemisphere ( Figure 5). ; (F) ice-core record of temperature anomaly from James Ross Island (JRI) [14]; (G) southern annular mode (SAM) index from [9] (grey) and [10] (black); (H) moss peatbank synthesis interpretations for the AP region [21]; (I) sea surface temperature (SST) from Palmer Deep [16]; (J) marine core interpretation from Barilari Bay [17]; (K) marine core interpretation from Bigo Bay [18]; (L) AP temperature anomaly [46]. [14]; (G) southern annular mode (SAM) index from [9] (grey) and [10] (black); (H) moss peatbank synthesis interpretations for the AP region [21]; (I) sea surface temperature (SST) from Palmer Deep [16]; (J) marine core interpretation from Barilari Bay [17]; (K) marine core interpretation from Bigo Bay [18]; (L) AP temperature anomaly [46].…”

“…Paleoclimate records from the AP have been derived from proxies archived in ice [14], marine sediments [15][16][17][18], and accumulations of peat [19][20][21][22][23]. Interestingly, opposite temperature trends have been noted on the western versus the eastern AP, which could be attributed to existence of an AP dipole [24].…”