[Coral-List] warming, acidification, reefs and CO2
sale at uwindsor.ca
Tue May 14 14:55:33 EDT 2013
If any of you have yet to see Reef Reminiscences, download a copy and
think about what we are losing:
The current discussions re acidification got to me.
Last week, CO2 concentration above Mauna Loa reached 400 ppm for the first
time since continuous records commenced in 1958. The long-term trend
since 1958 is becoming steeper (the rate of increase is growing).
Atmospheric CO2 was last at this level over 3 million years ago, well
before Homo sapiens evolved.
Growing atmospheric concentrations of CO2 lead to warming, and to ocean
acidification. Ocean surface temperatures have warmed measurably since
the start of industrialization, and pH of surface waters is declining at a
rate which appears to be more rapid than at any time in the last 450
million years. pH was virtually unchanged throughout the last 10,000
years, but has fallen 0.1 pH unit since start of industrialization, and is
expected to fall as much as 0.7 pH units over the next couple of centuries
if we do not wean our economies off fossil fuels (Zeebe 2012).
There are already studies showing effects of reduced pH on growth of some
corals, as well as studies showing deleterious effects on a range of other
marine species. Bleaching due to warming has had significant impacts on
coral cover on reefs worldwide, although mass bleaching was unknown until
first described by Peter Glynn in Panama and Galapagos in the early 1980s.
Bleaching-caused mortality and acidification-cause slowed growth act in
consort to further reduce the status of coral reefs (many of which are
already severely degraded by overfishing, pollution and inappropriate
coastal development). Live coral cover in shallow regions (~10m depth) of
the Great Barrier Reef has declined by 50% over the past 27 years, due
partly to bleaching losses. Data for the Caribbean are less robust, but
tell an equally or more depressing tale.
This week, the Prime Minister of Canada, Stephen Harper, will journey to
New York to give a speech in which he will extoll the value to the United
States of building the Keystone XL pipeline (jobs and oil for USA), while
also claiming a strong commitment by his government to the environment.
That commitment is hard to discern. Tar sands oil extraction is by far
the most polluting form of oil production around, both in CO2 emissions
and in other forms of pollution (chiefly heavy metals in waterways).
Canada is third, globally, in its per capita emissions of CO2. The Harper
government pulled Canada out of Kyoto, has no plan to achieve its own
(weak) target for emissions reductions by 2020, and still has not put in
place emissions regulations for the tar sands industry. This government
is also the one that keeps getting written up in Science and Nature for
its anti-science agenda.
True, not building Keystone XL will only slow, not stop, Canada's tar
sands industry. and Canada's total emissions of CO2 are a tiny percentage
of the world total. But as someone who would like coral reefs to persist,
I think we have to start somewhere if we are going to change our ways.
Stopping one pipeline is one small step on a long road to save coral
reefs. Some things in life are more important than the bottom line.
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