Green Mountains and White Plains: The Effect of Northern Hemisphere Ice Sheets on the Global Energy Budget

The changes in the global energy budget in response to imposing an ice sheet’s topography, albedo, or topography and albedo combined are examined. The albedo of the ice sheet (here called a “White Plain”) causes an outgoing top of the atmosphere radiation anomaly over the ice sheet that is balanced by an incoming anomaly in the Southern Hemisphere. This causes a northward transport of heat across the equator that is carried equally by the ocean and atmosphere. The topography of the ice sheet (“Green Mountain”) causes an incoming radiation anomaly over the ice sheet that is balanced predominantly by an outgoing anomaly to the south of the ice sheet, with a smaller outgoing flux in the Southern Hemisphere. The heat is transported across the equator by the atmosphere alone. The combined topography and albedo of the ice sheet (“White Mountain”) cause an outgoing radiation anomaly over the ice sheet that is balanced equally by an incoming flux in the Southern Hemisphere and to the south of the ice sheet. Heat is transported across the equator by the ocean alone.

With varying ice sheet geometry generally linear relationships between the various energy fluxes and the varying height and area of the ice sheet are found. In both the White Plain and White Mountain cases the ocean is always a significant carrier of heat across the equator, and in the White Mountain case it is preeminent.