Rapid recent warming on Rutford Ice Stream, West Antarctica, from borehole thermometry

Abstract

[1] The Antarctic Peninsula has warmed faster than the global average rate of warming during the last century. Due to limited availability of long term meteorological records, the geographical extent of this rapid warming is poorly defined. We collected borehole temperature measurements in the upper 300 m of Rutford Ice Stream, West Antarctica, and employed an inverse modeling scheme with a heat diffusion-advection equation to determine the recent surface temperature history of the borehole position. Our results reveal recent warming of 0.17 ± 0.07°C (decade) À1 since 1930. This result suggests that, at least in an attenuated form, the rapid warming observed over the Antarctic Peninsula extends as far south as Rutford Ice Stream. This result agrees with other recent results that show a warming trend across much of the West Antarctic Ice Sheet.

Borehole temperatures reveal a changed energy budget at Mill Island, East Antarctica, over recent decades

“…Such an approach of using both a forward model and a method of optimising surface temperature histories has been used previously (see, for example Johnsen, 1977;MacAyeal et al, 1991;Johnsen et al, 1995;Cuffey et al, 1995;Cuffey and Clow, 1997;Dahl-Jensen et al, 1998Barrett et al, 2009;Muto et al, 2011;Orsi et al, 2012). The forward models used in these studies all included the heating associated with firn densification with the exceptions of MacAyeal et al (1991);Johnsen et al (1995); Barrett et al (2009) and Muto et al (2011).…”

“…The forward models used in these studies all included the heating associated with firn densification with the exceptions of MacAyeal et al (1991);Johnsen et al (1995); Barrett et al (2009) and Muto et al (2011). These studies all select which possible surface temperature history reconstructions to accept based on minimising the mismatch between the simulated and observed borehole temperature profiles.…”

“…Johnsen, 1977;Cuffey et al, 1995;Cuffey and Clow, 1997;Johnsen et al, 1995); (ii) Monte Carlo based approaches (e.g. Dahl-Jensen et al, 1998Barrett et al, 2009); and (iii) generalised least-squares solution of a linearised version of the problem (e.g. MacAyeal et al, 1991;Muto et al, 2011;Orsi et al, 2012).…”

An assessment and interpretation of the observed warming of West Antarctica in the austral spring

“…Inversions of borehole temperature profiles also show warming on lowfrequency timescales (e.g. Barrett et al 2009). …”

“…Schneider and Steig 2008;Thomas et al 2009) and boreholes (e.g. Barrett et al 2009) have also been developed to infer West Antarctic climate variability and trends over the past years. An average of the ice core water stable isotope timeseries from West Antarctica suggests persistent warming through the second half of the twentieth century (Schneider and Steig 2008), as do ice cores from the western side of the Antarctic Peninsula (e.g.…”