Thawing permafrost also delivers organic - rich soils to lake bottoms, where decomposition in the absence of oxygen releases additional methane.116 Extensive wildfires also release carbon that contributes to climate warming.107, 117,118 The capacity of the Yukon River Basin in Alaska and adjacent Canada to store carbon has been substantially weakened since the 1960s by the combination of warming and thawing of permafrost and by increased wildfire.119 Expansion of tall shrubs and trees into tundra makes the surface darker and rougher, increasing absorption of the sun's energy and further contributing to warming.120 This warming is likely stronger than the potential cooling effects of increased carbon dioxide uptake associated with tree and shrub expansion.121 The shorter snow - covered seasons in Alaska further increase energy absorption by the land surface, an effect only slightly offset by the reduced energy absorption of highly reflective post-fire snow - covered landscapes.121 This spectrum of changes in Alaskan and other high - latitude terrestrial ecosystems jeopardizes efforts by society to use ecosystem carbon management to offset fossil fuel emissions.94
Thawing permafrost also delivers organic - rich soils to lake bottoms, where decomposition in the absence
of oxygen releases additional methane.116
Extensive wildfires also release carbon that contributes to climate warming.107, 117,118 The capacity
of the Yukon River Basin in Alaska and adjacent Canada to store carbon has been substantially weakened since the 1960s by the combination
of warming and
thawing of permafrost and by increased wildfire.119 Expansion of tall shrubs and trees into tundra makes the surface darker and rougher, increasing absorption of the sun's energy and further contributing to warming.120 This warming is likely stronger than the potential cooling effects of increased carbon dioxide uptake associated with tree and shrub expansion.121 The shorter snow - covered seasons in Alaska further increase energy absorption by the land surface, an effect only slightly offset by the reduced energy absorption of highly reflective post-fire snow - covered landscapes.121 This spectrum of changes in Alaskan and other high - latitude terrestrial ecosystems jeopardizes efforts by society to use ecosystem carbon management to offset fossil fuel emissions.94
thawing of permafrost and by increased wildfire.119 Expansion
of tall shrubs and trees into tundra makes the surface darker and rougher, increasing absorption
of the sun's energy and further contributing to warming.120 This warming is likely stronger than the potential cooling effects
of increased carbon dioxide uptake associated with tree and shrub expansion.121 The shorter snow - covered seasons in Alaska further increase energy absorption by the land surface, an effect only slightly offset by the reduced energy absorption
of highly reflective post-fire snow - covered landscapes.121 This spectrum
of changes in Alaskan and other high - latitude terrestrial ecosystems jeopardizes efforts by society to use ecosystem carbon management to offset fossil fuel emissions.94, 95,96