Present-day springtime high-latitude surface albedo as a predictor of simulated climate sensitivity

Simulations by the Community Atmosphere Model (CAM) and 15 other climate models suggest that climate sensitivity is linked to continental middle to high latitude present-day springtime albedo. We compare 1 × CO₂ and 2 × CO₂ CAM simulations against similar simulations with snow cover fraction purposely increased. Greater snow cover fraction leads to higher albedo and lower temperatures at 1 × CO₂ but has less influence at 2 × CO₂ when little snow remains due to global warming. This makes the simulation with higher albedo at 1 × CO₂ more sensitive to increased CO₂, in agreement with past work. We show that the wide variation in simulated snow-albedo feedbacks and climate sensitivities among 15 other models correlates well with variations in the continental middle to high latitude present-day springtime albedo, in agreement with our CAM results. The development of more accurate snow and albedo parameterizations should improve model estimates of climate sensitivity.