Carbon Dioxide and Earth's Future Pursuing the ... - Magazooms

www.co2science.org
P a g e | 90
In another study, Lewis, et al. (2009a), in a thorough review of the scientific literature, noted
that both theory and experiments suggest that over the past several decades “plant
photosynthesis should have increased in response to increasing CO2 concentrations, causing
increased plant growth and forest biomass,” and they did indeed find that “long-term plot data
collectively indicate an increase in carbon storage, as well as significant increases in tree
growth, mortality, recruitment, and forest dynamism,” that satellite measurements “indicate
increases in productivity and forest dynamism,” and that five Dynamic Global Vegetation
Models, incorporating plant physiology, competition, and dynamics, all predict increasing gross
primary productivity, net primary productivity, and carbon storage when forced using latetwentieth
century climate and atmospheric CO2 concentration data,” while noting that “the
predicted increases in carbon storage via the differing methods are all of similar magnitude
(0.2% to 0.5% per year).” And so they concluded that “these results point toward a widespread
shift in the ecology of tropical forests, characterized by increased tree growth and accelerating
forest dynamism, with forests, on average, getting bigger (increasing biomass and carbon
storage).”
Contemporaneously, Tans (2009) employed measurements of atmospheric and oceanic carbon
contents, along with reasonably constrained estimates of global anthropogenic CO2 emissions,
to calculate the residual fluxes of carbon (in the form of CO2) from the terrestrial biosphere to
the atmosphere (+ values) or from the atmosphere to the terrestrial biosphere (- values),
obtaining the results depicted in the following figure.
Five-year smoothed rates of carbon transfer from land to air (+) or from air to land (-) vs.
time. Adapted from Tans (2009).
[ search engine powered by magazooms.com ]