Arctic Amplification during the Last Glacial Inception due to a delayed
response in sea ice and surface temperature
Abstract
The last glacial inception (LGI) marks the transition from the
interglacial warm climate to the glacial period with extensive Northern
Hemisphere ice sheets and colder climate. This transition is initiated
by decreasing summer insolation but requires positive feedbacks to
stimulate the appearance of perennial snow. We perform simulations of
LGI with climate model AWI-ESM-2.1, forced by the radiative and
greenhouse gas forcing of 115,000 years before present. To compare with
the preindustrial (PI) simulation, we use a consistent definition of the
seasons during the LGI and the PI and evaluating model output on an
angular astronomical calendar. Our study reveals a prominent role of sea
ice in the albedo feedback to amplify the delayed climate siregnal at
polar latitudes. Through a radiative budget analysis, we examine that
the ice-albedo feedback exceeds the shortwave radiative forcing,
contributing to the cooling and high latitude snow built-up during LGI.