This report posted in Energy 23 August 2012 reveals that a new ice core from the Antarctic Peninsula shows that temperatures in the region during the past 10 000 years have often been higher than they are today, and that warming of the sort seen there recently has also occurred in the pre-industrial past. The new data is derived from a massive 364 metre long core extracted from the ice sheet lying on the top of James Ross island towards the northern tip of the Antarctic Peninsula in the freezing Weddell Sea. The core was extracted by scientists from the British Antarctic Survey, assisted by a French team. As a result of this it has been possible to reconstruct local temperatures and snowfall way back to the end of the last ice age. The Ross Island ice core results have made it into Nature magazine.
The results show that while the high rate of warming over the past century is unusual it is not unprecedented in the context of natural climate variability over the past two millennia.. Natural millennial scale climate variability has resulted in warming on the eastern Antarctic Peninsula that has been ongoing for a number of centuries and has left ice shelves in this area vulnerable to collapse. The Nature article reveals that there is evidence for instability of the Larsen A ice shelf between 3800 and 1400 years ago. Ice shelves along the shores of the Waddell Sea have snapped off in the pre-industrial past and may well snap off in coming years. The idea that they must result from man made carbon emissions does not seem credible.
(see report in the register www.the register.co.uk/2012/08/23/antarctic_peninsula_ice_core/)