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

9. Frequent Coral Bleaching
The claim: Rising ocean temperatures driven by CO2-induced global warming is killing the
world's corals.
www.co2science.org
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Bleaching is the name of the phenomenon given to the process whereby the corals inhabiting
earth’s seas expel the algal symbionts or zooxanthellae living within their tissues (upon which
they depend for their sustenance) when subjected to various environmental stresses, one of
the most discussed of which is excessive warmth. And as a result of this discussion, primarily
among climate alarmists, global warming has long been claimed by them to be one of the
primary reasons for mandating reductions in anthropogenic CO2 emissions, in order to prevent
our driving numerous species of corals to extinction. But is this contention based on sound
science?
With respect to corals adapting to greater warmth, Adjeroud et al. (2005) documented -- in a
study of 13 islands in four of the five archipelagoes of French Polynesia -- the effects of natural
perturbations on various coral assemblages over the period 1992-2002, during which time the
reefs were subjected to three major coral bleaching events (1994, 1998, 2002). Finding that the
impacts of the bleaching events were variable among the different study locations, and that “an
interannual survey of reef communities at Tiahura, Moorea, showed that the mortality of coral
colonies following a bleaching event was decreasing with successive events, even if the latter
have the same intensity (Adjeroud et al., 2002),” they concluded that the “spatial and temporal
variability of the impacts observed at several scales during the present and previous surveys
may reflect an acclimation and/or adaptation of local populations,” such that “coral colonies
and/or their endosymbiotic zooxanthellae may be phenotypically (acclimation) and possibly
genotypically (adaptation) resistant to bleaching events,” citing the work of Rowan et al. (1997),
Hoegh-Guldberg (1999), Kinzie et al. (2001) and Coles and Brown (2003) in support of this
conclusion.
Other researchers have confirmed the phenomenon of thermal adaptation in coral reefs.
Guzman and Cortes (2007), for example, studied reefs of the eastern Pacific Ocean that
“suffered unprecedented mass mortality at a regional scale as a consequence of the anomalous
sea warming during the 1982-1983 El Niño.” In a survey of three representative reefs they
conducted in 1987 at Cocos Island, for example, they found that remaining live coral cover was
only 3% of what it had been prior to the occurrence of the great El Niño four years earlier
(Guzman and Cortes, 1992); and based on this finding and the similar observations of other
scientists at other reefs, they predicted that “the recovery of the reefs’ framework would take
centuries, and recovery of live coral cover, decades.”
In 2002, however, nearly 20 years after the disastrous coral-killing warming, they returned to
see just how prescient they might have been after their initial assessment of the El Niño’s
horrendous damage, quantifying the live coral cover and species composition of five reefs,
including the three they assessed in 1987. And in doing so, they found that overall mean live
coral cover had increased nearly five-fold, from 3% in 1987 to 14.9% in 2002, at the three sites
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