Widespread Biological Response to Rapid Warming on the Antarctic Peninsula

Recent climate change on the Antarctic Peninsula is well documented [1-5], with warming, alongside increases in precipitation, wind strength, and melt season length [1, 6, 7], driving environmental change [8, 9]. However, meteorological records mostly began in the 1950s, and paleoenvironmental datasets that provide a longer-term context to recent climate change are limited in number and often from single sites [7] and/or discontinuous in time [10, 11]. Here we use moss bank cores from a 600-km transect from Green Island (65.3°S) to Elephant Island (61.1°S) as paleoclimate archives sensitive to regional temperature change, moderated by water availability and surface microclimate [12, 13]. Mosses grow slowly, but cold temperatures minimize decomposition, facilitating multi-proxy analysis of preserved peat [14]. Carbon isotope discrimination (Δ(13)C) in cellulose indicates the favorability of conditions for photosynthesis [15]. Testate amoebae are representative heterotrophs in peatlands [16-18], so their populations are an indicator of microbial productivity [14]. Moss growth and mass accumulation rates represent the balance between growth and decomposition [19]. Analyzing these proxies in five cores at three sites over 150 years reveals increased biological activity over the past ca. 50 years, in response to climate change. We identified significant changepoints in all sites and proxies, suggesting fundamental and widespread changes in the terrestrial biosphere. The regional sensitivity of moss growth to past temperature rises suggests that terrestrial ecosystems will alter rapidly under future warming, leading to major changes in the biology and landscape of this iconic region-an Antarctic greening to parallel well-established observations in the Arctic [20].This research was funded by the UK Natural Environment Research Council (NERC) Antarctic Funding Initiative grant 11/05 (NE/H014896/1) held by D.J.C., D.A.H., P.C., and H.G. P.C., D.A.H., and J.R. contribute to the BAS “Polar Science for Planet Earth” research program. Radiocarbon analyses were supported by allocation number 1605.0312 from the NERC Radiocarbon Facility, East Kilbride. We gratefully acknowledge Professor Melanie Leng at the NERC Isotope Geosciences Laboratory for assistance with isotope measurements and Nicole Sanderson at the University of Exeter for assistance with 210Pb age modeling. Sample collection was supported by HMS Protector and HMS Endurance