New evidence
has been published that the Great Barrier Reef is not in trouble
from climate change. The effects of bleaching are short-lived and
reversible. When I said this in my book, I was patronised from a
great height by a bunch of marine biologists in New Scientist. Will
they, and New Scientist, now apologise? As I keep saying, coral
reefs are indeed under threat from man-made problems -- pollution,
overfishing, run-off, but climate change is the least of their
worries. Here's the abstract of Osborne et al's paper in PLOS
One:
Coral reef ecosystems worldwide are under
pressure from chronic and acute stressors that threaten their
continued existence. Most obvious among changes to reefs is loss of
hard coral cover, but a precise multi-scale estimate of coral cover
dynamics for the Great Barrier Reef (GBR) is currently lacking.
Monitoring data collected annually from fixed sites at 47 reefs
across 1300 km of the GBR indicate that overall regional coral
cover was stable (averaging 29% and ranging from 23% to 33% cover
across years) with no net decline between 1995 and 2009.
Subregional trends (10-100 km) in hard coral were diverse with some
being very dynamic and others changing little. Coral cover
increased in six subregions and decreased in seven subregions.
Persistent decline of corals occurred in one subregion for hard
coral and Acroporidae and in four subregions in non-Acroporidae
families. Change in Acroporidae accounted for 68% of change in hard
coral. Crown-of-thorns starfish (Acanthaster planci)
outbreaks and storm damage were responsible for more coral loss
during this period than either bleaching or disease despite two
mass bleaching events and an increase in the incidence of coral
disease. While the limited data for the GBR prior to the 1980's
suggests that coral cover was higher than in our survey, we found
no evidence of consistent, system-wide decline in coral cover since
1995. Instead, fluctuations in coral cover at subregional scales
(10-100 km), driven mostly by changes in fast-growing Acroporidae,
occurred as a result of localized disturbance events and subsequent
recovery.
Here's what i wrote in my book.
Take coral reefs, which are suffering
horribly from pollution, silt, nutrient runoff and fishing -
especially the harvesting of herbivorous fishes that otherwise keep
reefs clean of algae. Yet environmentalists commonly talk as if
climate change is a far greater threat than these, and they are
cranking up the apocalyptic statements just as they did wrongly
about forests and acid rain. Charlie Veron, an Australian marine
biologist: 'There is no hope of reefs surviving to even mid-century
in any form that we now recognise.' Alex Rogers of the Zoological
Society of London pledges 'an absolute guarantee of their
annihilation'. No wiggle room there. It is true that rapidly
heating the water by a few degrees can devastate reefs by
'bleaching' out the corals' symbiotic algae, as happened to many
reefs in the especially warm El Niño year of 1998. But bleaching
depends more on rate of change than absolute temperature. This must
be true because nowhere on the planet, not even in the Persian Gulf
where water temperatures reach 35C, is there a sea too warm for
coral reefs. Lots of places are too cold for coral reefs - the
Galapagos, for example. It is now clear that corals rebound quickly
from bleaching episodes, repopulating dead reefs in just a few
years, which is presumably how they survived the warming lurches at
the end of the last ice age. It is also apparent from recent
research that corals become more resilient the more they experience
sudden warmings. Some reefs may yet die if the world warms rapidly
in the twenty-first century, but others in cooler regions may
expand. Local threats are far more immediate than climate
change.
