To have even a chance of saving the world’s coral reefs from extensive damage caused by global warming, carbon emissions in industrialised countries need to be cut by 25% below their year 2000 levels by 2020 – and by 80-90% by 2050. That is the uncompromising warning delivered by some of Australia’s most eminent marine and environmental scientists in a briefing to Australian Members of Parliament and Senators, in Parliament House, Canberra.
“The Great Barrier Reef (GBR) contributes $5.4 billion annually to the Australian economy - $5.1 billion from the tourism industry; $153 million from recreational activity; and $139 million from commercial fishing. The ‘outstanding universal values’ of the GBR, recognised by its inclusion on the World Heritage List in 1981, are now threatened by rapid climate change,” Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University told the briefing.
"Professor Hughes emphasised the consensus among reef scientists in Australia about the impacts of climate change on valuable environmental assets such as the Great Barrier Reef. “We’ve seen the evidence with our own eyes. Climate change is already impacting the Great Barrier Reef and reefs in Western Australia.”According to Western Australian Premier's Fellow, Professor Malcolm McCulloch “Coral reefs are in the front line of the effects of climate change because of their sensitivity to both relatively small temperature rises and to acidification of the oceans due to increased levels of dissolved CO2. To date, atmospheric CO2 has risen to 390 parts per million, resulting in an increase in temperature of 0.7oC and a rise in ocean acidity of 0.1 unit of pH.”
Other leading scientists are equally concerned. “Unprecedented coral bleaching and extensive mortality due to thermal stress affected over 50 per cent of the GBR in 1998 and 2002, when summer maximum water temperatures were elevated by only 1-2oC. Some parts of the GBR have still not fully recovered,” Professor Ove Hoegh-Guldberg of the ARC Centre and the University of Queensland adds.
“Ocean acidification is accelerating and, in combination with thermal stress, has already detrimentally affected the growth and skeletal strength of corals on the GBR,” he says. “Ocean acidification will impact all marine calcifying organisms, potentially disrupting the entire ecology of the world’s oceans, resulting in severe socio-economic impacts on fisheries and other marine industries.”
“Coral cover is already declining on the GBR and globally, even on the most remote and best-managed reefs. Loss of coral cover reduces biodiversity, ultimately affecting fishing, tourism, coastal protection and World Heritage values,” Professor Ove Hoegh-Guldberg says.
Professor Hughes and colleagues advised the parliamentarians that the effects of atmospheric concentrations above 450 parts per million CO2 equivalent (currently seen as the most likely target to emerge from Copenhagen) and the consequent likely temperature increase of more than 2oC on the GBR “will be devastating, particularly given the impacts observed so far with only one-third this amount of warming.”
“A stabilisation level of no more than 450 parts per million in the concentration of CO2-equivalent greenhouse gases in the atmosphere could achieve, at best, an even chance of constraining warming below the 2°C target. To achieve even this 50:50 chance of avoiding 2°C of warming would require global emissions to peak no later than 2020, and then decline to 80-90 per cent below 2000 emissions by 2050.”
“To have a realistic chance of achieving this target, emissions from industrialised countries in 2020 need to be reduced by at least 25 per cent relative to their 2000 levels.”
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