A multi-century ice-core perspective on 20th-century climate change with new contributions from high-Arctic and Greenland (PARCA) cores

Abstract

A global collection of high temporally resolved ice-core-derived δ18O records is examined to assess whether the proxy records are consistent with contemporaneous observed temperature variations in their respective regions. This is prerequisite to using the older parts of the proxy (δ18O) records to assess whether 20th-century temperatures remain within the range of longer-term natural variability. Excluding the high plateaus in East and West Antarctica where 20th-century temperatures show modest cooling, the ice-core records from other regions suggest modest to strong 20th-century warming. The recent warming over Greenland has been modest and spatially variable. The 20th-century warming over both the Barents Sea region and the Tibetan Plateau now falls well outside the range of prior longer-term temperature variability. Similarly, over the South American Andes and the Antarctic Peninsula the recent warming exceeds the long-term mean for the last 1000 and 500 years, respectively. The ice fields in these regions are in danger of being compromised or lost if the present warming trend in these regions persists.