The unavoidable disaster coming to our coral reefs

Posted on July 15th, 2012 in ecology,Environment by Robert Miller

If you haven’t read Roger Bradbury’s op-ed piece in the New York Times, published yesterday, this a good time to familiarize yourself with it. Roger is an adjunct professor, specialized in coral reefs and ecological issues at the Crawford School, a public policy branch of the Australian National University. In his article, he raises the issue that to me is suitably alarmist. Our coral reefs, with their rich biodiversity will be gone and it seems unlikely that unless we put an emergency effort into halting the processes that are destroying these gems, including a rapid reduction in atmospheric carbon dioxide, they will vanish, reducing the ocean in those regions to something like it was in the Precambrian era of 500 million years ago when it was rich in algae, jelly fish and very few  fish. The culprits are the ones we already know about—overfishing—acidification of the oceans through the absorption of atmospheric carbon dioxide—and pollution, the latter influence being the hardest to know about  because we don’t have models to predict a large-scale experiment that has never been done. He begins his article by stating that “IT’S past time to tell the truth about the state of the world’s coral reefs, the nurseries of tropical coastal fish stocks. They have become zombie ecosystems, neither dead nor truly alive in any functional sense, and on a trajectory to collapse within a human generation. There will be remnants here and there, but the global coral reef ecosystem — with its storehouse of biodiversity and fisheries supporting millions of the world’s poor — will cease to be.
Bradbury refers to a recent statement that came out of a The International Coral Reef Symposium, in which scientists signed a statement supporting immediate action to prevent an imminent coral reef disaster:
Consensus Statement on Climate Change and Coral Reefs

The international Coral Reef Science Community calls on all governments to ensure the future of coral reefs, through global action to reduce the emissions of carbon dioxide and other greenhouse gases, and via improved local protection of coral reefs. Coral reefs are important ecosystems of ecological, economic and cultural value yet they are in decline worldwide due to human activities. Land-based sources of pollution, sedimentation, overfishing and climate change are the major threats, and all of them are expected to increase in severity.

Changes already observed over the last century:

  • Approximately 25-30% of the world’s coral reefs are already severely degraded by local impacts from land and by over-harvesting.
  • The surface of the world’s oceans has warmed by 0.7°C, resulting in unprecedented coral bleaching and mortality events.
  • The acidity of the ocean’s surface has increased due to increased atmospheric CO2.
  • Sea-level has risen on average by 18cm.

By the end of this century:

  • CO2 emissions at the current rate will warm sea surface temperatures by at least 2-3°C, raise sea-level by as much as 1.7 meters, reduce ocean pH from 8.1 to less than 7.9, and increase storm frequency and/or intensity. This combined change in temperature and ocean chemistry has not occurred since the last reef crisis 55 million years ago.

Other stresses faced by corals and reefs:

  • Coral reef death also occurs because of a set of local problems including excess sedimentation, pollution, habitat destruction, and overfishing.
  • These problems reduce coral growth and vitality, making it more difficult for corals to survive climate changes.

Future impacts on coral reefs:

  • Most corals will face water temperatures above their current tolerance.
  • Most reefs will experience higher acidification, impairing calcification of corals and reef growth.
  • Rising sea levels will be accompanied by disruption of human communities, increased sedimentation impacts and increased levels of wave damage.

Together, this combination of climate-related stressors represents an unprecedented challenge for the future of coral reefs and to the services they provide to people.

Across the globe, these problems cause a loss of reef resources of enormous economic and cultural value. A concerted effort to preserve reefs for the future demands action at global levels, but also will benefit hugely from continued local protection.

The scientific warnings about imminent threats to our environment have gone unheeded, due in large part to the influence of capitalist forces that control the global political agenda. With the threatened destruction of most of our coral reefs within a few generations if not sooner, we are faced with a catastrophe that we may see during our lifetime, one that may usher in a whole new series of rapid changes to livelihoods from the sea and starving populations who now depend on the coral reef system for sustenance.  We tend to study the effects of these global forces degrading coral reefs, but not the rate at which their powers of destruction operate to diminish our future. Rate is everything, but very hard to predict. We are still early in the sixth species extinction, but we are gaining momentum and there is no doubt that this one is appropriately referred to as the anthropogenic species destruction because the offending party is us. Once these processes start, they can’t be stopped and this logic applies as well to the melting of the Greenland Ice and the Polar icecaps, but especially that of Antarctica. If we reduced atmospheric carbon dioxide tomorrow, we would have at least fifty years of reef destruction and global climate change conditions. These changes will be with us no matter what we do, but beyond that period, by reducing emissions and poisoning of the coral reefs, we might stand a chance of eventually seeing them restored. It is of course an issue about whether we have the political will to create a national movement that insists on habitat preservation, though this concept has become far more complex today that it was twenty years ago. The destruction of the global economy fits neatly into creating a national pause in the pursuit of overdue fixes to stabilize our environmental future.

RFM

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