Name
Dr. Jiping Liu
Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, NY, USA

Title
Diminishing Arctic Sea Ice and its Impacts on Winter Climate

Time and place
Thu 30 May 2013, 14.15
Room C609, Arrhenius Laboratory, 6th floor

(This event has taken place)

 

Abstract
Arctic sea ice has undergone dramatic decline in recent years, which further raises the specter of an ice-free Arctic in the 21st century. We find that large spread in the projected timing of the ice-free Arctic in newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The spread is associated with at least as much with different atmospheric model components and model resolution as with initial conditions. We reduce the spread in the timing of the ice-free state using two different approaches for the CMIP5 models: 1) model selection based on the ability to reproduce the observed sea ice climatology and variability, and 2) constrained estimation based on the strong and persistent relationship between present and future sea ice conditions. The two different approaches show good agreement. Under a high-emission scenario both approaches project that September ice extent will drop to ~1.7 million km2 in the mid 2040s and reach the ice-free state in 2054-2058. Under a medium-mitigation scenario, both approaches project a decrease to ~1.7 million km2 in the early 2060s, followed by a leveling off.

While the Arctic region has been warming strongly in recent decades associated with the decline of Arctic sea ice, anomalously large snowfall in recent winters has affected large parts of North America, Europe, and East Asia. We demonstrate that extensive retreat of Arctic sea ice in summer and its slow recovery in autumn could alter winter atmospheric circulation that is different from the winter Arctic Oscillation. Such circulation change leads to broader meridional meanders in mid-latitudes, more frequent episodes of blocking circulations and cold air outbreaks in much of northern continents. Moreover, the increase of atmospheric water vapor content in the Arctic region during late autumn and winter driven locally by the pronounced ice loss provides enhanced moisture sources, supporting increased large snowfall in Europe during early winter, and in the northeastern and mid-west United States during winter. Recent loss of Arctic sea ice, with its signature on atmospheric circulation and moisture source, may load the dice in favor of northern continental snowy winters.