Abstract
Abstract. A borehole temperature record from the Mill Island (East Antarctica) icecap reveals a large surface warming signal manifested as a 0.75 K temperature difference over the approximate 100 m depth in the zone of zero annual amplitude below the seasonally varying zone. The temperature profile shows a break in gradient around 49 m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/81 AD ±5 yr. This warming of approximately 0.37 K per decade is consistent with trends seen in both instrumental and other reconstructions for Antarctica and, therefore, suggests that regional- rather than local-scale processes are largely responsible. Alteration of the surface energy budget arising from changes in radiation balances due to local cloud, the amount of liquid deposition and local air temperatures associated with altered air/sea exchanges also potentially plays a role at this location due to the proximity of the Shackleton Ice Shelf and sea-ice zone.
Highlights
Palaeoclimate records provide an essential context for present-day climate, and they help us to understand the drivers of climate change
The initial choice of the surface temperature history differs in both form and values for the least squares QR (LSQR) and particle swarm optimisation (PSO) methods, which are detailed in Sects. 3.2.1 and 3.2.2 respectively
The temperature profile down an ice borehole into the Mill Island icecap shows a distinct change of gradient around 49 m below the surface
Summary
Palaeoclimate records provide an essential context for present-day climate, and they help us to understand the drivers of climate change. The relatively large uncertainties (likely due to data sparsity) in Southern Hemisphere palaeoreconstructions (Mann and Jones, 2003; Mann et al, 2008) are of comparable size to the recent warming, so that the Southern Hemisphere situation is more ambiguous Records from sites such as Mill Island help address this data sparsity and provide insights into the rate of change over the past century. Previous regional studies on late Holocene paleoclimate have demonstrated a relationship between Law Dome summer temperature in Wilkes Land and evaporation in Ace Lake in the Vestfold Hills, Princess Elizabeth Land (Roberts et al, 2001) In the absence of long-term meteorological observations, the general climate overview for Mill Island can be approximated from Mirny Station at 66◦33 S, 93◦01 E that indicates prevailing east-southeasterly winds (Turner and Pendlebury, 2004)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
