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A new study confirms that the threat from CO2 is exaggerated

A new study of the Great Barrier Reef will
apparently confirm what I argued in The Rational Optimist that
local pollution and over-fishing are a much greater threat to coral
reefs than either climate change or changing alkalinity (sometimes
wrongly called acidification).

The actual paper will appear in Current Biology,
but this is from the press release from James Cook University (I
hate it when scientists announce their results by press release
before the journal article is available).

Update: here’s the article in press, but behind a

Quoting one of the authors, Terry Hughes:

“This study has
given us a more detailed understanding of the sorts of changes that
could take place as the world’s oceans gradually warm and

“And it has
increased our optimism about the ability of coral reef systems to
respond to the sorts of changes they are likely to experience under
foreseeable climate change.”

The good news
from the research, says Professor Hughes, is that complete reef
wipeouts appear unlikely due to temperature and pH

“However, in
many parts of the world, coral reefs are also threatened by much
more local impacts, especially by pollution and over-fishing. We
need to address all of the threats, including climate change, to
give coral reefs a fighting chance for the future.”

The press release gives more details of the

They identified
and measured a total of 35,428 coral colonies on 33 reefs from
north to south. Studying corals on both the crests and slopes of
the reef, they found that as one species decreases in abundance,
another tends to increase, and that species wax and wane largely
independently of each other.


“We chose the
iconic Great Barrier Reef because water temperature varies by 8-9
degrees along its full length from summer to winter, and because
there are wide local variations in pH. In other words, its natural
gradients encompass the sorts of conditions that will apply several
decades from now under business-as-usual greenhouse gas

This is a point that I have been emphasising
recently: that natural variation in ocean pH is already greater
than any future trend likely from carbon emissions.

By Matt Ridley | Tagged:  rational-optimist