The
MC1 Dynamic General Vegetation Model (DGVM) was used to assess the impacts of
global warming on North American ecosystems, north of Mexico, under 6 future climate
scenarios (3 General Circulation Models X 2 emission scenarios). The simulations were begun in 1900 using
observed climate and CO2 until 2000, then transferring to the future
scenarios to 2100. Carbon sequestration
over the continent occurred in the late 20th century and for a short
period into the 21st century, being fostered largely by increased
precipitation, enhanced water-use efficiency and mild temperature
increases. However, these ‘greening’
processes were overtaken by the exponential effects of increasing temperature
on evaporative demand and respiration, producing a subsequent decline. Simulation
experiments suggested that fire suppression could significantly mitigate the
carbon losses, yet many ecosystems were still forced to a lower carrying
capacity.
Author: R.P. Neilson, J.M. Lenihan, D. Bachelet, et al (rneilson at fs dot fed dot us)
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