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

Jonathan M Stelling,Zicheng Yu

doi:10.3390/geosciences9070282

Abstract

The Antarctic Peninsula (AP) climate is characterized by a high degree of variability, which poses a problem when attempting to put modern change in the context of natural variation. Therefore, novel methods are required to disentangle sometimes conflicting climate records from the region. In recent years, the development of Antarctic moss-cellulose isotopes as a proxy for summer terrestrial growing conditions has become more widespread, with the isotopes Δ13C and δ18O reflecting moss productivity and peatbank moisture conditions, respectively. Here, we used a combined Δ13C and δ18O isotope analysis of moss Chorisodontium aciphyllum cellulose from a peatbank located on Litchfield Island in the western AP to document changes in climate over the last 1700 years. High Δ13C values (>15‰) indicate warm and productive conditions on Litchfield Island from 1600 to 1350 cal yr BP (350 to 600 AD) and over the last 100 years. The δ18O record shows two distinct intervals of dry conditions at 1350–1000 cal yr BP (600–950 AD) and at 500–0 cal yr BP (1450–1950 AD). Our record indicates that terrestrial ecosystems in the AP have responded to regional climate driven by atmospheric circulation, such as the southern annular mode (SAM) and, to a lesser extent, changes in ocean circulation.

Highlights

Rapid change in glaciers and ecosystems on the Antarctic Peninsula (AP) have been attributed to warming climate over the 20th century [1]
Modern climate on the AP is driven by synoptic-scale patterns that fluctuate between two phases related to the southern annular mode (SAM)
Moss isotopes from peatbanks have proven to be informative for paleoclimate interpretations in the western Antarctic Peninsula

Summary

Introduction

Rapid change in glaciers and ecosystems on the Antarctic Peninsula (AP) have been attributed to warming climate over the 20th century [1]. Despite an accelerated increase in atmospheric CO2 , there has been a lack of warming trend across the AP over the last 20 years (Figure 1), indicating that recent warming in the AP region may be within natural variability [2,3,4]. The climate variability over the southern hemisphere in general, and the AP is characterized by strong regional and seasonal contrasts and a coupling of atmospheric, oceanic, sea-ice, and ice-sheet processes [5]. Understanding atmospheric and ocean circulation patterns can provide insight into what climate regimes operated over the AP in the past. Modern climate on the AP is driven by synoptic-scale patterns that fluctuate between two phases related to the southern annular mode (SAM).

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Conclusion