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Pristine Reef

Coral communities like this in an island sanctuary were once commonplace. They are now becoming increasingly rare, especially in regions where there are no good management practices to protect them.

Coral Bleaching

A bleached coral garden. The corals that have retained some colour are likely to recover; those that have turned completely white are more likely to die. Blue colonies (centre) may also be completely bleached.

Coral Rubble

After corals are killed, the result rapidly becomes a flat rubble substrate devoid of protection for herbivorous fish. Provided that environmental conditions are good, this coral community could recover in a decade.

Reef of the future?

A reef of the future? Five years after all the corals on this reef in Papua New Guinea were killed by a mass bleaching event there are no signs of recovery. The coral skeletons are covered by a layer of filamentous slime.

 
Coral Reefs and Climate Change
Coral reefs worldwide are threatened with total extinction this century if urgent action is not taken to reduce anthropogenic carbon dioxide emissions.
  • Extensive damage to reefs is currently coming from greenhouse temperature increases causing mass death through 'bleaching'.
  • The ultimate threat will ultimately come from ocean acidification caused by absorption of carbon dioxide by surface waters.
  • These impacts are due to the rate at which greenhouse gases are being produced, which is far exceeding that of any previous time in the history of the Earth.

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Change in CO2 levels from the GBR's most likely time of origin to its foreseeable future in a business-as-usual world. At this scale, the increase the anthropogenic CO2 spike is a vertical line. If this diagram were re-drawn with a horizontal axis 250 metres long, the spike would still be a vertical line.

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Current rate of atmospheric CO2 increase (in ppm) from instrumental records of the past and computer model projections of the future. The midrange scenario assumes that most of the remedial actions now being proposed are put into effect within a decade. The worst-case scenario (which is an optimistic position according to some energy industry scientists) assumes that these remedial actions are not implemented or are ineffective. Both scenarios in this diagram undervalue the opposing influences of sulphur dioxide in dampening the greenhouse effect and the plans of developing countries to build extensive coal-fired power stations, which will enhance it.

Be part of the debate: www.climateshifts.org