Can how much sunlight spring snow reflects help explain why climate models predict different amounts of warming?

Details

Simulations using the Community Atmosphere Model (CAM) and 15 other climate models suggest that climate sensitivity is linked to present-day springtime albedo—the fraction of sunlight reflected—over continental areas at middle to high latitudes.

The researchers compared CAM simulations at 1 × CO2 and 2 × CO2 with otherwise similar simulations in which the snow cover fraction was deliberately increased. Greater snow cover fraction produced higher albedo and lower temperatures at 1 × CO2. It had less influence at 2 × CO2, when little snow remained because of global warming.

As a result, the simulation with higher albedo at 1 × CO2 was more sensitive to increased CO2, consistent with past work.

Across the 15 other models, the wide variation in simulated snow–albedo feedbacks and climate sensitivities correlated well with differences in present-day springtime albedo over middle- to high-latitude continents. This agreed with the CAM results.

The researchers conclude that developing more accurate snow and albedo parameterizations should improve model estimates of climate sensitivity.