The Future of Coral Reefs

John Quiggin, Australian economist and popular blogger, participated in the Coral Reef Futures Forum since one of his many roles is to look at the economics of the Great Barrier Reef.

In addition to shedding light on the progress and consequences of global warming, Quiggin’s post also provides informative comments on what he calls delusionist theories. He mentions in passing the UK controversy over the movie “An Inconvenient Truth.” The movie was slotted to be presented in schools, which an irate parent sought to block. A High Court judge found the movie to be broadly accurate and ruled the airing should proceed, provided the discussion materials covered the fact that there were nine “errors” (and by that he meant points that were contested rather than untrue, but that distinction was often missed by the press). The judge appears to have missed the mark in some of his assessments.

Quiggin also touches on ocean acidification, a product of rising atmospheric CO2 levels that threatens marine life. However, a worrisome story on the BBC reports that absorption of CO2 had fallen by 50% in the Atlantic. While the news may be a plus for the oceans (or just noise in the data), if it means that the oceans will be taking up less CO2 than assumed, it also suggests that greenhouse gas levels will rise faster than previously modeled, meaning the progress of climate change may have been underestimated.

First, from the BBC:

The amount of carbon dioxide being absorbed by the world’s oceans has reduced, scientists have said.
University of East Anglia researchers gauged CO2 absorption through more than 90,000 measurements from merchant ships equipped with automatic instruments.

Results of their 10-year study in the North Atlantic show CO2 uptake halved between the mid-90s and 2000 to 2005.

Scientists believe global warming might get worse if the oceans soak up less of the greenhouse gas.

Researchers said the findings, published in a paper for the Journal of Geophysical Research, were surprising and worrying because there were grounds for believing that, in time, the ocean might become saturated with our emissions.

BBC environment analyst Roger Harrabin said: “The researchers don’t know if the change is due to climate change or to natural variations.

“But they say it is a tremendous surprise and very worrying because there were grounds for believing that in time the ocean might become ‘saturated’ with our emissions – unable to soak up any more.”

He said that would “leave all our emissions to warm the atmosphere”.

Of all the CO2 emitted into the atmosphere, only half of it stays there; the rest goes into carbon sinks.

There are two major natural carbon sinks: the oceans and the land “biosphere”. They are equivalent in size, each absorbing a quarter of all CO2 emissions.

Now from Quiggin:

As one of the speakers said, a lot of the talks had people staring at their shoes in gloom, though the tone got a little more positive towards the end. I’m an optimist on ecological issues which is fortunate, because when you look at the threats facing coral reefs, you need a lot of optimism. Looking at historical data, even the GBR, which is much better managed than most reef systems is significantly degraded relative to 100 years ago, and a large proportion of reefs are at or near the point of no return, thanks to overfishing, destructive fishing methods and marine pollution. When you add regular bleaching due to climate change, and also acidification due to higher CO2 levels, the chances of saving much of the world’s coral reef systems do not look too good.

The most hopeful view is that, if we can fix the local threats like overfishing and poor water quality, the resulting increase in resilience (part of my project is to develop a more rigorous understanding of this popular buzzword) will offset moderate global warming, so that if we can stabilise the climate (an increase of no more than 2 degrees) we might save at least some reef systems.

A few observations:

First, it’s noteworthy how opinion has solidified on the point that bleaching (corals expelling their associated symbiotic zooxanthellae ) is a response to higher temperature driven by general warming of the seas, rather than being due to locally specific causes. Al Gore’s claim to this effect, listed as an error in the recent court case that has been exciting the delusionists, has the full support of everyone I talked to there. Given the regular claim that any scientist who accepts the evidence on global warming must have been bought off by the prospect of grant money, let me observe that the problems we already had with coral reefs are enough to keep every marine biologist on the planet gainfully employed for life without inventing new ones.

Sticking with the delusionists, it’s striking that the McIntyre fan club has been digging up the sorriest dead horse in the annals of delusionism, the urban heat island effect, and has more generally been getting excited about land surface records. Of course, no one at this meeting paid any attention to land surface measurements. The sea temperature records are not influenced at all by UHI and they tell the same story. And of course the satellite data that used to get such a big run is ignored by delusionists now that it confirms the surface records. Unless (as I have while editing Wikipedia for the last few years) you’d seen exactly the same kind of thing play out over the health risks of smoking, evolution, AIDS reappraisal and so on, you would find it hard to believe that anyone could push this nonsense.

While delusionists were thin on the ground, the skepticism that is associated with good science was not. The idea that intact mangrove forests and coral reef systems might provide protection against the destructive effects of tsunamis is appealing, and has been widely promoted, but, it seems, doesn’t stand up to close scrutiny, and the evidence supporting it is an example of spurious correlation. At least that’s what Andrew Baird argued, and he seemed pretty convincing to me. Of course, this will be fought out in the peer-reviewed literature as it should be.

Another rather depressing point to come out was that acidification driven by higher atmospheric CO2 is worse in cold climates, which means that the prospect of reef systems migrating away from the equator in response to climate change is not promising. And of course this is a reminder that radically changing the composition of the atmosphere is going to have a whole lot of effects, which may interact in nasty and unexpected ways.

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