The world has a narrow window of opportunity to save coral reefs from the destruction of extreme climate change. Substantial global reductions of greenhouse gases must be initiated immediately, not in 10, 20 or 50 years, Australian scientists have said.
Over 50 experts attached to the Australian Research Council's Centre of Excellence for Coral Reef Studies have issued a joint statement, stressing that without targeted reductions, the ongoing damage to coral reefs from global warming would soon become irreversible.
Ocean acidification due to increased atmospheric CO2 is accelerating, and will detrimentally effect the growth and skeletal strength of calcifying species, such as corals. Reducing CO2 emissions is the only way to prevent further damage to coral reefs. Loss of coral also impacts on many other species and reduces reef fisheries, they said.
"Coral reefs are economically, socially and culturally important, and therefore need to be sustained. For example, the Great Barrier Reef contributes $6.9 billion annually to the Australian economy - $6 billion from the tourism industry, $544 million from recreational activity and $251 million from commercial fishing. This economic activity generates more than 65 000 jobs.
Climate change, overfishing and pollution continue to cause massive and accelerating declines in abundance of coral reef species and global changes in reef ecosystems. Even remote and well-managed reefs are under threat from climate change," they said.
The experts went on to point out that coral bleaching had greatly increased in frequency and magnitude over the past 30 years due to global warming. For coral reefs, climate change was no more a potential future threat - it had already caused enormous damage that would increase in coming years. Bleaching due to climate change has already caused widespread damage to the Great Barrier Reef in 1998 and 2002.
No-fishing reserves (green zones) are an important management tool for preserving targeted stocks of coral reefs, and the ecological functions they provide. To be effective, 25-35% of marine habitats should be no-take (no fishing) for long-term protection. In Australia, many coral reefs have yet to achieve this level of protection (especially in the Northern Territory, Western Australia, south-east Queensland, and the Coral Sea).
Coral reef megafauna (e.g. dugongs, turtles and sharks) continue to decline rapidly, and are ecologically extinct on most of the world's reefs. In Australia, current management practices are failing to maintain populations of megafauna, which are already severely depleted. Commercial harvesting and marketing of these species should be banned to allow the recovery of depleted stocks.
While the scientists conceded that local action could help re-build the resilience of reefs, and promote their recovery, they also stressed that it was critically important to prevent the replacement of corals by algal blooms, by reducing runoff from land and by protecting stocks of herbivorous fishes.
Still the bottom line is that reefs cannot be "climate-proofed" except via reduced emissions of greenhouse gases.