The Arctic is especially vulnerable to climate change and is warming faster than the global average. Changes in this region pose a heightened threat due to the immense amount of carbon frozen as organic material in the soil. When permafrost thaws, organic material decays and is released as greenhouse gases into the atmosphere, contributing to further warming. A better understanding of the processes that influence permafrost degradation is needed to inform climate adaptation and mitigation planning. This study assesses changes to Arctic permafrost across thirty-five ensemble member simulations from the Community Earth System Model (CESM1) Large Ensemble Project, under the RCP8.5 21st century scenario. Most Arctic permafrost is lost by 2100, but the timing varies across regions and with soil depth. Internal variability, represented by differences between ensemble members, has a constrained influence on degradation timing due to relative consistency of summer temperature increases and insulation by winter snow cover.