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

Abstract

A borehole temperature record from the Mill Island (East Antarctica) icecap reveals a large surface warming signal manifested as a 0.75K temperature difference over the approximate 100m depth in the zone of zero annual amplitude below the seasonally varying zone. The temperature profile shows a break in gradient around 49m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/81AD±5 yr. This warming of approximately 0.37K 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 respon..