Changes in Seasonal Surface Energy Balance of High-Latitude Ecosystems Under Warmer Climate

Authors

Zelalem Mekonnen1* (zmekonnen@lbl.gov), William Riley1, Ian Shirley1, Nick Bouskill 1, Robert Grant2, Colleen Iversen3

Institutions

1Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA; 2Department of Renewable Resources, University of Alberta–Edmonton, Canada; 3Oak Ridge National Laboratory, Oak Ridge, TN

URLs

Abstract

With rapid climate warming, expected changes in high-latitude vegetation and snow-pack dynamics may alter the surface albedo. The extent to which changes in surface albedo may alter surface energy balances and thus soil temperatures of northern ecosystems is uncertain. Researchers applied a processes-rich ecosystem model (EcoSys) to examine changes in seasonal surface energy balance driven by changes in albedo across Alaska. Under a warmer 21st century climate, surface albedo was modeled to decrease mainly during spring. This decline is particularly driven by increases in snow-free periods and extended length of growing season. Despite a decline in spring albedo, researchers modeled a slight increase in summer albedo as a result of vegetation change that led to a higher proportion of aspen, which was modeled to have a higher leaf albedo than black spruce in the boreal forest. Modeled latent heat fluxes were generally shown to increase, particularly during spring and summer. Overall, these changes in energy fluxes resulted in 3 ± 0.34°C increase in spatially averaged surface soil temperatures across Alaskan ecosystems by the year 2100. Researchers conclude that seasonal changes in surface energy fluxes of northern ecosystems under warmer climates are primarily driven by vegetation and snowpack dynamics.