SWAIS2C – The Sensitivity of the West Antarctic Ice Sheet to 2 degrees of Warming - Results from Crary Ice Rise.

The SWAIS2C program examines the Sensitivity of the West Antarctic Ice Sheet to 2 degrees Celsius of warming. The central aim of SWAIS2C is to use geological archives obtained from West Antarctica to assess the state of the ice sheet during past climate states. Project partners include the International Continental Scientific Drilling Program (ICDP), and a consortium of national Antarctic programs and international collaborators. Here we present the initial findings from SWAIS2C’s 217m-long drill core recovered during the 2025/26 field season from beneath Crary Ice Rise (CIR), West Antarctica (S 83.0267, W 172.6258; ICDP Site 5072_2_A). Drilling at CIR required a 515 m deep access hole to be melted through the ice and then the drilling of 228 m of core in permafrost conditions. Drilling was accomplished with the Antarctic Intermediate Depth Drill (AIDD) system, a modified geotechnical rig, which included hot water delivery to the cutting face. The AIDD recovered 217 m of core (95 % recovery). The core was assigned to five lithostratigraphic units based on grain size, biogenic content, and lithological sequences representing subglacial to ice-free environments. Natural gamma ray downhole logging data supports the placement of these unit boundaries. Initial biostratigraphic age estimates from the lowermost lithostratigraphic unit suggests a maximum age of middle Miocene (~17 Ma). The cyclic pattern evident in the stratigraphy provides direct evidence of a dynamic and climate sensitive WAIS from the Mid-Miocene to recent. Successful integration of hot water drilling and the AIDD system provides a basis for future drilling beneath polar ice sheets where observations are lacking but are needed to better constrain the likely response of ice sheets like the WAIS to future warming.