Decadal–Interdecadal Climate Variability over Antarctica and Linkages to the Tropics: Analysis of Ice Core, Instrumental, and Tropical Proxy Data

Abstract

The Antarctic continent contains the majority of the global ice volume and plays an important role in a changing climate. The nature and causes of Antarctic climate variability are, however, poorly understood beyond interannual time scales due to the paucity of long, reliable meteorological observations. This study analyzes decadal-interdecadal climate variability over Antarctica using a network of annually resolved ice core records and various instrumental and tropical proxy data for the nineteenth and twentieth centuries. During the twentieth century, Antarctic ice core records indicate strong linkages to sea surface temperature (SST) variations in the tropical Pacific and Atlantic on decadal-interdecadal time scales. Antarctic surface temperature anomalies inferred from the ice cores are consistent with the associated changes in atmospheric circulation and thermal advection. A set of atmospheric general circulation model experiments supports the idea that decadal SST variations in the tropics force atmospheric teleconnections that affect Antarctic surface temperatures. When coral and other proxies for tropical climate are used to extend the analysis back to 1799, a similar Antarctic-tropical Pacific linkage is found, although the relationship is weaker during the first half of the nineteenth century. Over the past 50 years, a change in the phase of Pacific and Atlantic interdecadal variability may have contributed to the rapid warming of the Antarctic Peninsula and West Antarctica and related changes in ice sheet dynamics.

Tropical Connections to Climatic Change in the Extratropical Southern Hemisphere: The Role of Atlantic SST Trends

“…A large proportion of these circulation trends have been connected to the modes of high-latitude atmospheric variability associated with the El Niño-Southern Oscillation (ENSO), representing the Pacific-South American (PSA) teleconnection patterns (Schneider et al 2012a). Climatic change in West Antarctica is thus strongly sensitive to teleconnections associated with Pacific SST variability, as also identified in recent paleoclimate studies (Okumura et al 2012;Steig et al 2013).…”

“…Nevertheless, Luffman et al (2010) suggest that long-term Indian Ocean warming likely has a minimal impact on the SH atmospheric circulation. Conversely, Okumura et al (2012) identify links between Atlantic SST variability and the climate of West Antarctica, and argue that a change in the phase of this variability may have contributed to contemporary climate trends in this region, as also corroborated by Li et al (2014). However, the dynamical mechanisms forcing this association remain largely unexplored, and as such, several questions remain.…”

“…On interannual time scales, Southern Hemisphere (SH) teleconnections associated with SST variability in the Pacific have been well documented (e.g., Karoly 1989;Mo and Higgins 1998;Garreaud and Battisti 1999;Ciasto and Thompson 2008;Ciasto and England 2011;Ding et al 2011;Schneider et al 2012a,b;Simpkins et al 2012). In contrast, relatively few studies have examined the corresponding teleconnections arising from the Atlantic or Indian Oceans (exceptions include Haarsma and Hazeleger 2007;Luffman et al 2010;Timmermann et al 2010;Taschetto et al 2011;Okumura et al 2012;Taschetto and Ambrizzi 2012;Li et al 2014), particularly beyond interannual time scales. Nevertheless, Luffman et al (2010) suggest that long-term Indian Ocean warming likely has a minimal impact on the SH atmospheric circulation.…”

“…Particular emphasis is placed on understanding teleconnections associated with the Atlantic, and thus we build upon the studies of Okumura et al (2012) and Li et al (2014). To this end, we use an atmospheric general circulation model (AGCM) in addition to observations to address the following: 1) what impact, if any, do SST trends in the Pacific, Indian, and Atlantic Oceans have on extratropical geopotential height trends in the SH between 1979-2009?…”

New Reconstruction of Antarctic Near-Surface Temperatures: Multidecadal Trends and Reliability of Global Reanalyses*,+

“…The contrast with respect to East Antarctica can be traced, again, to a greater imprint of ENSO in West Antarctica (e.g., Bromwich et al 2000Bromwich et al , 2004Guo et al 2004;Gregory and Noone 2008;Schneider and Steig 2008;Okumura et al 2012). On the annual scale, the area of significant negative correlations is roughly limited to the Ross Sea sector of West Antarctica.…”