I have an article in The Times today (behind a paywall) on
ocean acidification. Here’s the gist:
Today in Beijing an alliance of
scientists called Oceans United will present the United Nations
with a request for $5 billion a year to be spent on monitoring the
oceans. High among their concerns is ocean acidification, which
`could make it harder for animals such as lobsters, crabs,
shellfish, coral or plankton to build protective
shells’.
As opinion polls reveal that global
warming is losing traction on the public imagination, environmental
pressure groups have been cranking the engine on this `other carbon
dioxide problem’. `Time is running out’ wrote two activists in
Scientific American in August, `to limit acidification before it
irreparably harms the food chain on which the world’s oceans – and
people – depend.’
The trouble is, a shoal of new
scientific papers points to the conclusion that this scare is based
on faulty biochemical reasoning, unrealistic experiments and
exaggeration.
We have been here before. In 1984,
acid rain was the environmental scare of the day. As the science
correspondent of The Economist, I wrote: `Forests are beginning to
die at a catastrophic rate. One year ago, West Germany estimated
that 8% of its trees were in trouble. Now 34% are…that forests
are in trouble is now indisputable.’ Experts told me all Germany’s
conifers would be gone by 1990 and the Federal Ministry of the
Interior predicted all forests would be gone by 2002.
Bunk. Acid rain (though a real
phenomenon) did not kill forests. It did not even damage them.
Scientists eventually admitted that forests thrived in Germany,
Scandinavia and North America during the 1980s and 1990s, despite
acid rain. I was a gullible idiot not to question the conventional
wisdom I was being fed by those with vested interests in
alarm.
Talking of vested interests, the
European Project on Ocean Acidification (EPOCA) is now a consortium
of over 100 scientists from 27 institutes and 9 countries. This
last summer it funded 35 scientists to spend six weeks in the
Arctic studying the problem, `assisted’ by Greenpeace’s ship
Esperanza. Think how little incentive the scientists would have to
say `sorry, lads, we realize it is a not much of an issue after
all’.
Start with a few facts. The oceans
are not acid but alkaline, with an average pH of about 8.15 (0-7
being acid, 7-14 being alkaline). But they vary both in space and
time, Arctic seas being less strongly alkaline than tropical, and
some bays and reefs being actually acid because of underwater
volcanic emissions. The dissolution of carbon dioxide in the oceans
may lower the pH slightly to about 7.9 or 7.8 by the end of the
century at the worst – still alkaline.
Environmentalists like to call this a
30% increase in acidity, because it sounds more scary than a 0.3
point (out of 14) decrease in alkalinity, but no matter. It is
still well within the bounds of normal variation over space and
time: the pH of the water intake at the Monterey aquarium varies by
almost twice as much as this every month. The difference between
the pH of the seas off Hawaii and Alaska is greater than
this.
Enough numbers. Try chemistry. The
scary reasoning rests on the argument that lower pH will mean less
dissolved carbonate in the water. But a new paper from scientists
in North Carolina proves what many scientists have long suspected,
namely that corals and other species do not use carbonate as raw
material to make their shells; they use bicarbonate. And dissolving
carbon dioxide in water actually increases bicarbonate
concentrations.
This may explain why study after
study keeps finding that far from depressing growth rates of marine
organisms, high but realistic levels of carbon dioxide either do
not affect them or increase them. By far the most important
calcifiers in the oceans are plankton called coccolithophores,
which account for about a third of the total marine calcium
carbonate manufacture. There is now strong evidence that
coccolithophores are growing faster and larger as a result of human
carbon dioxide emissions. Stands to reason if they use
bicarbonate.
Studies of oyster sperm, cuttlefish
eggs, juvenile sea stars, coral polyps and krill all point to the
same conclusion: damage only occurs when carbon dioxide levels
reach ludicrous levels, not expected for many centuries. A
new study of plankton concluded: `Thus, both of the
investigated coastal plankton communities were unaffected by
twenty-first century expected changes in pH and free
CO2.’
When I voiced some of these doubts in
my book The Rational Optimist, I was accused of cherry-picking
studies. All right, so let’s take a look at a `meta-analysis’, that
is to say a comprehensive paper summarising all relevant studies.
Iris Hendriks and Carlos Duarte of the Spanish Council for
Scientific Research found that in 372 studies of 44 different
marine species `there was no significant mean effect’ from lower
pH. They concluded that the world’s marine biota are `more
resistant to ocean acidification than suggested by pessimistic
predictions’ and that ocean acidification `may not be the
widespread problem conjured into the 21st century.’
Before I started looking into this, I
assumed the evidence for damage from ocean acidification must be
strong because that is what the media kept saying. I am amazed by
what I have found. Make no mistake: there are lots of threats to
the ecosystems of the ocean, from over-fishing to nutrient run-off,
but acidification is way down the list. The attention is deflecting
funds and action from greater threats. It is time scientists had
the courage to admit this.