Vulnerability of arctic and tropical carbon to changing climate (Invited)
Abstract
The future trajectory of the global climate system depends, in part, on what happens to the earth's major pools of organic carbon. The largest and most vulnerable pools are stored in tropical forests and the organic soils of boreal and arctic biomes. The fate of the organic carbon stored in tropical and boreal ecosystems will depend on how plants respond to both average climate change (e.g. mean change in temperature and precipitation) and the associated changes to extreme weather events (e.g. droughts). In the arctic there is evidence a biome shift is taking place, with warmer drier climate leading to forest productivity changes, increased tree mortality and unprecedented fire events that alter the composition of successional pathways. In the tundra regions the warmer climate has led to increases in woody vegetation, total landscape biomass, and altered albedo and net radiation. Warming in the arctic also has the potential to release ancient organic carbon to the atmosphere via permafrost thaw. In contrast, large areas of the moist tropical forests are being altered by land-use practices and increasingly severe weather. People are clearing, thinning, and changing the composition of forests. Severe, episodic droughts are superimposed upon these land-use activities, thereby increasing forest susceptibility and mortality to escaped management fires. The deforestation and forest degradation have led to significant direct transfer of carbon from aboveground biomass pools to the atmosphere. We report on use of field measurements, satellite observations, and numerical models to quantify historical and potential future changes in arctic-boreal and tropical terrestrial productivity as a function of natural and human-induced land cover and climate disturbances. We contend that both arctic-boreal and tropical biomes are strongly influenced by the same fundamental biophysical processes controlling carbon exchange. These include changes in productivity, tree mortality, the frequency and severity of disturbance, it's implications for post-disturbance vegetation structure and function, and the influence of climate. We argue that drought, expressed as extended vapor pressure deficits, plays a critical role in driving these interacting processes in each of these biomes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.B11K..01G
- Keywords:
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- 0428 BIOGEOSCIENCES Carbon cycling;
- 0429 BIOGEOSCIENCES Climate dynamics;
- 0426 BIOGEOSCIENCES Biosphere/atmosphere interactions;
- 0466 BIOGEOSCIENCES Modeling