Overfishing, ocean acidification and pollution
are pushing coral reefs into oblivion. Each of those forces alone is fully
capable of causing the global collapse of coral reefs; together, they assure it.
The scientific evidence for this is compelling and unequivocal, but there seems
to be a collective reluctance to accept the logical conclusion — that there is
no hope of saving the global coral reef ecosystem.
What we hear instead is
an airbrushed view of the crisis — a view endorsed by coral reef scientists,
amplified by environmentalists and accepted by governments. Coral reefs, like
rain forests, are a symbol of biodiversity. And, like rain forests, they are
portrayed as existentially threatened — but salvageable. The message is: “There
is yet hope.”
Indeed, this view is echoed in the “consensus statement” of
the just-concluded International Coral Reef Symposium, which called “on all
governments to ensure the future of coral reefs.” It was signed by more than
2,000 scientists, officials and conservationists.
This is less a conspiracy
than a sort of institutional inertia. Governments don’t want to be blamed for
disasters on their watch, conservationists apparently value hope over truth, and
scientists often don’t see the reefs for the corals.
But by persisting in
the false belief that coral reefs have a future, we grossly misallocate the
funds needed to cope with the fallout from their collapse. Money isn’t spent to
study what to do after the reefs are gone — on what sort of ecosystems will
replace coral reefs and what opportunities there will be to nudge these into
providing people with food and other useful ecosystem products and services. Nor
is money spent to preserve some of the genetic resources of coral reefs by
transferring them into systems that are not coral reefs. And money isn’t spent
to make the economic structural adjustment that communities and industries that
depend on coral reefs urgently need. We have focused too much on the state of
the reefs rather than the rate of the processes killing them.
Overfishing,
ocean acidification and pollution have two features in common. First, they are
accelerating. They are growing broadly in line with global economic growth, so
they can double in size every couple of decades. Second, they have extreme
inertia — there is no real prospect of changing their trajectories in less than
20 to 50 years. In short, these forces are unstoppable and irreversible. And it
is these two features — acceleration and inertia — that have blindsided us.

Overfishing can bring down reefs because fish are one of the key functional
groups that hold reefs together. Detailed forensic studies of the global fish
catch by Daniel Pauly’s lab at the University of British Columbia confirm that
global fishing pressure is still accelerating even as the global fish catch is
declining. Overfishing is already damaging reefs worldwide, and it is set to
double and double again over the next few decades.
Ocean acidification can
also bring down reefs because it affects the corals themselves. Corals can make
their calcareous skeletons only within a special range of temperature and
acidity of the surrounding seawater. But the oceans are acidifying as they
absorb increasing amounts of carbon dioxide from the atmosphere. Research led by
Ove Hoegh-Guldberg of the University of Queensland shows that corals will be
pushed outside their temperature-acidity envelope in the next 20 to 30 years,
absent effective international action on emissions.
We have less of a handle
on pollution. We do know that nutrients, particularly nitrogenous ones, are
increasing not only in coastal waters but also in the open ocean. This change is
accelerating. And we know that coral reefs just can’t survive in nutrient-rich
waters. These conditions only encourage the microbes and jellyfish that will
replace coral reefs in coastal waters. We can say, though, with somewhat less
certainty than for overfishing or ocean acidification that unstoppable pollution
will force reefs beyond their survival envelope by midcentury.
This is not a
story that gives me any pleasure to tell. But it needs to be told urgently and
widely because it will be a disaster for the hundreds of millions of people in
poor, tropical countries like Indonesia and the Philippines who depend on coral
reefs for food. It will also threaten the tourism industry of rich countries
with coral reefs, like the United States, Australia and Japan. Countries like
Mexico and Thailand will have both their food security and tourism industries
badly damaged. And, almost an afterthought, it will be a tragedy for global
conservation as hot spots of biodiversity are destroyed.
What we will be
left with is an algal-dominated hard ocean bottom, as the remains of the
limestone reefs slowly break up, with lots of microbial life soaking up the
sun’s energy by photosynthesis, few fish but lots of jellyfish grazing on the
microbes. It will be slimy and look a lot like the ecosystems of the Precambrian
era, which ended more than 500 million years ago and well before fish evolved.

Coral reefs will be the first, but certainly not the last, major ecosystem
to succumb to the Anthropocene — the new geological epoch now emerging. That is
why we need an enormous reallocation of research, government and environmental
effort to understand what has happened so we can respond the next time we face a
disaster of this magnitude. It will be no bad thing to learn how to do such
ecological engineering now. NYTimes