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

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With respect to animals facing the challenge of global warming, climate alarmists generally
characterize the situation as highly dangerous for them, just as they do for plants, suggesting
that rising temperatures will also drive many of them to extinction. However, and once again
as with plants, most research on the subject suggests otherwise.
A good place to begin a review of this subject is a study on butterflies conducted by a group of
thirteen researchers in 1999 (Parmesan et al., 1999). These scientists analyzed, over the prior
century of global warming, the distributional changes of non-migratory species whose northern
boundaries were in northern Europe (52 species) and whose southern boundaries were in
southern Europe or northern Africa (40 species). This work revealed that the northern
boundaries of the first group shifted northward for 65% of them, remained stable for 34%, and
shifted southward for 2%, while the southern boundaries of the second group shifted
northward for 22% of them, remained stable for 72%, and shifted southward for 5%, such that
“nearly all northward shifts,” according to Parmesan et al., “involved extensions at the northern
boundary with the southern boundary remaining stable.”
This behavior is precisely what we would expect to see if the butterflies were responding to
shifts in the ranges of the plants upon which they depend for their sustenance, because
increases in atmospheric CO2 concentration tend to ameliorate the effects of heat stress in
plants and induce an upward shift in the temperature at which they function optimally. These
phenomena tend to cancel the impetus for poleward migration at the warm edge of a plant’s
territorial range, yet they continue to provide the opportunity for poleward expansion at the
cold edge of its range. Hence, it is possible that the observed changes in butterfly ranges over
the past century of concomitant warming and rising atmospheric CO2 concentration are related
to matching changes in the ranges of the plants upon which they feed. Or, this similarity could
be due to some more complex phenomenon, possibly even some direct physiological effect of
temperature and atmospheric CO2 concentration on the butterflies themselves. In any event,
and in the face of the 0.8°C of “dreaded” global warming that occurred in Europe over the 20th
century, the consequences for European butterflies were primarily beneficial, because, as
Parmesan et al. described the situation, “most species effectively expanded the size of their
range when shifting northwards,” since “nearly all northward shifts involved extensions at the
northern boundary with the southern boundary remaining stable.”
A number of other researchers have also studied the relationship between butterflies and
temperature. In the British Isles, Thomas et al. (2001) documented an unusually rapid
expansion of the ranges of two butterfly species (the silver-spotted skipper butterfly and the
brown argus butterfly) in response to increasing temperatures. In the United States, Crozier
(2004) noted that “Atalopedes campestris, the sachem skipper butterfly, expanded its range
from northern California into western Oregon in 1967, and into southwestern Washington in
1990,” where she reports that temperatures rose by 2-4°C over the prior half-century. And in
Canada, White and Kerr (2006) reported butterfly species’ range shifts across the country
between 1900 and 1990, noting that butterfly species richness increased as “a result of range
expansion among the study species” that was “positively correlated with temperature change.”
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