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

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As can be seen from this figure, earth’s land surfaces were a net source of CO2-carbon to the
atmosphere until about 1940, primarily due to the felling of forests and the plowing of
grasslands to make way for expanded agricultural activities. From 1940 onward, however, the
terrestrial biosphere has become, in the mean, an increasingly greater sink for CO2-carbon; and
it has done so even in the face of massive global deforestation, for which it has more than
compensated. And in light of these findings, plus the fact that they do “not depend on models”
but “only on the observed atmospheric increase and estimates of fossil fuel emissions,” Tans
concluded that “suggestions that the carbon cycle is becoming less effective in removing CO2
from the atmosphere (e.g., LeQuere et al., 2007; Canadell et al., 2007) can perhaps be true
locally, but they do not apply globally, not over the 50-year atmospheric record, and not in
recent years.” In fact, he goes on to say that “to the contrary” and “despite global fossil fuel
emissions increasing from 6.57 GtC in 1999 to 8.23 in 2006, the five-year smoothed global
atmospheric growth rate has not increased during that time, which requires more effective
uptake [of CO2] either by the ocean or by the terrestrial biosphere, or both, to satisfy
atmospheric observations.” And the results portrayed in the figure we have adapted from Tans’
paper clearly indicate that this “more effective uptake” of CO2-carbon has occurred primarily
over land.
The story reported on a continent by continent basis is much the same as it is for the globe as a
whole. Consequently, and in order to curtail the size of this burgeoning treatise, in what
follows we provide only references, grouped by continent, of studies where real-world data
have documented the greening of the earth phenomena.
For Africa, Prince et al. (1998), Eklundh and Olsson (2003), Anyamba and Tucker (2005), Olsson
et al. (2005), Seaquist et al. (2006), Ciais et al. (2009) and Lewis et al. (2009b). For Asia,
Fang et al. (2003), Piao et al. (2005a), Brogaard et al. (2005), Piao et al. (2005b), Lapenis et al.
(2005), Piao et al. (2006a), Schimel et al. (2001), Kharuk et al. (2006), Piao et al. (2006b), Tan et
al. (2007), Piao et al. (2007), Zhou et al. (2007), Zhu et al. (2007), Mu et al. (2008), Mao et al.
(2009), Zhuang et al. (2010) and Forbes et al. (2010). For Australia, Harrington and Sanderson
(1994), Russell-Smith et al. (2004) and Banfai and Bowman (2006). For Europe, Osborne et al.
(2000), Lopatin et al. (2006), Martinez-Vilalta et al. (2008), Alcaraz-Segura et al. (2008) and
Hallinger et al. (2010). For North America, Hicke et al. (2002), Westfall and Amateis (2003), Lim
et al. (2004), Peterson and Neofotis (2004), Xiao and Moody (2004), Soule and Knapp (2006),
Tape et al. (2006), Wang et al. (2006), Voelker et al. (2006), Piao et al. (2006c), Hudson and
Henry (2009), Springsteen et al. (2010), Pan et al. (2010) and Cole et al. (2010). And for South
America, Beerling and Mayle (2006) and Silva et al. (2009).
Given the above findings, our assessment of the future of earth’s natural and agro-ecosystems
is indeed bright. Crop yields will increase by a goodly amount over the course of this century,
and tree and shrub growth will surge even more, as the air’s CO2 content continues to promote
a great greening of the earth.
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