Similar warming and cooling trends occurred in the mid-nineteenth and eighteenth centuries
From AGU highlights:
A 308-year ice core record provides new data on climate variability in coastal West Antarctica and shows that a clear warming trend has occurred in recent decades. To study climate over the past 3 centuries, Thomas et al. analyzed stable isotopes in the ice core, which provide a record of past temperatures. They observe that climate variability in coastal West Antarctica is strongly driven by sea surface temperatures and atmospheric pressure in the tropical Pacific.
The authors report that their ice core record shows that the region warmed since the late 1950s at a rate similar to that observed in the Antarctic Peninsula and central West Antarctica.
However, the authors note that this recent warming trend is similar in magnitude to warming and cooling trends that occurred in the mid-nineteenth and eighteenth centuries in their record, indicating that in this coastal West Antarctic location the effects of human-induced climate change in recent years have not exceeded natural climate variability over the past 300 years.
Source: Geophysical Research Letters, doi:10.1002/2013GL057782, 2013 http://onlinelibrary.wiley.com/doi/10.1002/2013GL057782/abstract
Title: A 308 year record of climate variability in West Antarctica
Authors: Elizabeth R. Thomas, Thomas J. Bracegirdle and John Turner: British Antarctic Survey, Cambridge, UK; Eric W. Wolff: Department of Earth Sciences, University of Cambridge, Cambridge, UK.
We present a new stable isotope record from Ellsworth Land which provides a valuable 308 year record (1702–2009) of climate variability from coastal West Antarctica. Climate variability at this site is strongly forced by sea surface temperatures and atmospheric pressure in the tropical Pacific and related to local sea ice conditions. The record shows that this region has warmed since the late 1950s, at a similar magnitude to that observed in the Antarctic Peninsula and central West Antarctica; however, this warming trend is not unique. More dramatic isotopic warming (and cooling) trends occurred in the mid-nineteenth and eighteenth centuries, suggesting that at present, the effect of anthropogenic climate drivers at this location has not exceeded the natural range of climate variability in the context of the past ~300 years.