Snow and Climate

Modeling simulations over boreal Alaska have documented changes in albedo due to changes in the duration of the snow season and due to changes in the amount of young forest stands on a landscape due to changes in the fire regime. In addition, changes in the exchange of the greenhouse gases CO2 and methane have also been estimated due to changes in climate, atmospheric carbon dioxide concentrations, fire regimes, and methane emissions. The sum of these feedbacks indicates that changes in boreal Alaska acted to warm the atmosphere between 1970-2000 and between 2003-2100. The strongest feedback to climate warming was derived from a lengthening of the growing season (reducing the snow-albedo feedback) between 2003-2100, and this was only partially counterbalanced by the cooling effect of an increase in the amount of young stands in the landscape under more severe fire regimes, and increases in carbon uptake by terrestrial ecosystems between. Furthermore, under a warmer, wetter climate the amount of methane released from Alaska’s peatlands increased between 1970-2000 and between 2003-2100, acting as an additional positive feedback to climate warming.