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Global Warming imperils coral reefs: 2 degrees Celsius warming is too hot say scientists
Increasing sea surface temperatures are imperilling coral reef ecosystems say scientists. A new scientific paper with extensive modelling reveals that atmospheric warming of 2 degrees celsius is too much for nearly all the world's coral reef ecosystems. They argue that to preserve greater than 10 per cent of coral reefs worldwide would require limiting global warming to below 1.5 °C. This equates to the goal of reducing carbon in the atmosphere to 350ppm, rather than a 2 degree rise or 450ppm that the UN Framwework Convention on Climate Change has adopted as the safe limit at several meetings. Atmospheric concentration of CO2 currently stands at 392.41ppm.
Corals are sensitive to water temperature. With ocean temperatures increasing with global warming mass coral bleaching events are occurring more often and projected to increase in frequency and intensity this century.
When climate changed in the past it was over thousands or tens of thousands of years allowing coral organisms and ecosystems a chance to shift range or adapt to the changing environment. But we are changing the global environment so rapidly with atmospheric and ocean temperature increases, pollution and runoff from agricultural and land use practices, overfishing the world's oceans, and increasing CO2 which is increasing ocean acidification, that coral reef ecosystems do not have any time to adapt or relocate.
The paper says that "Even under optimistic assumptions regarding corals' thermal adaptation, one-third (9-60%, 68% uncertainty range) of the world's coral reefs are projected to be subject to long-term degradation under the most optimistic new IPCC emissions scenario."
The other major problem corals face is Ocean acidification which reduces the ability of coral and other sea creatures to build their calcerous shells. This reduces the thermal tolerance of these creatures.
The paper - Limiting global warming to 2 °C is unlikely to save most coral reefs (Full paper) argues
Despite the inclusion of optimistic scenarios concerning rates of evolutionary adaptation, our results confirm that coral reef ecosystems face considerable challenges under even an ambitious mitigation scenario that constrains global warming to 1.5 °C above pre-industrial temperatures. Our projections suggest that most coral reefs will experience extensive degradation over the next few decades given the present behaviour of corals to thermal stress.
Threat to coral reefs known for some yearsMarine Biologists have been warning of the threats to coral reef ecosystems for some years. Professor Ove Hoegh-Guldberg attended the Copenhagen talks in 2009 and warned that Extinction threatens Coral Reefs unless CO2 limited to 350ppm. That same year marine and climate scientists appealed for at least a 25% cut in carbon emissions from developed countries like Australia to save the Great Barrier Reef.
In July 2012 an International Coral Reef Symposium held in Cairns warned that coral reefs around the world are in rapid decline. Over 2000 scientists released a consensus statement on Climate Change and Coral Reefs. (See bottom of this post for statement)
In a media release Professor Terry Hughes, Convener of the Symposium and Director of the ARC Centre of Excellence for Coral Reef Studies stated:
"When it comes to coral reefs, prevention is better than cure. If we look after the Great Barrier Reef better than we do now, it will continue to support a vibrant tourism industry into the future" he said.
Strategies for conservation
While scientists urged action to reduce carbon pollution, they also advocated many positive local actions that could be undertaken to bolster resilience in reef ecosystems including:
Natalie Ban, an ARC Postdoctoral Fellow in Program 6 (Conservation Planning for a Sustainable Future) at the ARC Centre of Excellence for Coral Reef Studies at James Cook University talked about the Strategies for conservation under climate change. (Youtube Video
Mass coral bleaching and mortality events have been observed since the 1980s. Often it takes 10 to 20 years or more for a reef ecosystem to recover from a bleaching event.
Differences between Caribbean and Indo-Pacific coral systems
But not all coral reefs have been impacted the same. Reef systems in the Caribbean have suffered more degradation to date than coral reef ecosystems in the Indo-Pacific region. Dr George Roff and Professor Peter Mumby from the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland presented a paper in July which argued that coral reefs in the Indo-Pacific Ocean are naturally tougher than the Caribbean reefs.
"The main reason that Indo-Pacific reefs are more resilient is they have less seaweed than the Caribbean Sea," Dr Roff said. "Seaweed and corals are age-old competitors in the battle for space. When seaweed growth rates are lower, such as the Indo-Pacific region, the reefs recover faster from setbacks. This provides coral with a competitive advantage over seaweed, and our study suggests that these reefs would have to be heavily degraded for seaweeds to take over.
Tipping points, Regime shifts and living on borrowed time
As atmospheric and ocean temperatures increase, the frequency and intensity of bleaching events will degrade reef ecosystems with a steady regime shift over many years from coral dominance to macro-algal dominance composed of organisms such as algae, seaweeds and jellyfish. Here is Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies, talking on Tipping points, regime shifts and borrowed time in a 38 minute talk. (Youtube video)
The cost of saving reef ecosystems
So do we just say goodbye to our coral reef ecosystems? Have a think about the impact. Coral reefs provide habitat for over a million species. That is a lot of biodiversity to lose. Approximately half a billion people are dependent wholly or to some extent on the productivity of coral reefs. Are we ready to transfer their dependence on ocean productivity to land productivity?
Professor Ove Hoegh-Guldberg did a presentation at the symposium at the cost of saving reef ecosystems. IPCC analysis concluded that slowing global GDP growth by 0.12 per cent a year over the next 50 years would be enough to stabilise global temperature.
"That expenditure is the equivalent to taking off one year of GDP growth over the next 50 years," Professor Hoegh-Guldberg said.
Australia takes a small step declaring marine reserves network
The Australian Government took a small step forward in June 2012 when Federal Environment Minister Tony Burke announced the world's largest network of marine reserves, including in the coral sea. While commercial fishing operators were disgruntled at the announcement, the Australian Conservation Foundation said it would have little impact on recreational fishing and help with recovery of fish stocks and eliminate destructive bottom trawling. Laurence McCook PhD, Pew Fellow in Marine Conservation, on Benefits of Marine Reserves (Youtube video)
ACF's healthy oceans campaigner Chris Smyth said in a media release: "Recreational fishers will also benefit because of the removal of bottom trawling from almost the entire Coral Sea Marine Reserve and commercial tuna longlining from a large area along the eastern boundary of the Great Barrier Reef Marine Park. Recent scientific research around the Barrier Reef found causal links between marine reserves and the subsequent recovery of ocean life and its spill over into fished areas."
"Most people living on the coast will see through the wildly exaggerated and unfounded claims made by scaremongers about the economic impact of marine reserves" he said, "While some commercial fishers will need to make changes to where or how they fish or may choose to leave the industry, the government will provide up to $100 million in funding to help them adjust to the national network."
"Australian and international scientists agree there is a need to reduce cumulative pressure on oceans from fishing, the oil and gas sector and climate change." he concluded.
The announcement was endorsed by the IUCN World Conservation Congress meeting in South Korea who called it one of the most significant advances for marine environmental protection in Australia's history and urged global community to support similar initiatives. The initiative was started by the Howard Government in 1998.
Oil and gas mining have been banned from the Coral Sea reserve and the reserve located off the Margaret River area of South West Australia.
You can watch a 21 minute video presentation published in March 2012 on Climate Change and the projection of coral reef futures by Professor Sean Connolly, Chief Investigator and Program Leader with the ARC Centre of Excellence for Coral Reef Studies and a Professorial Fellow within the School of Marine and Tropical Biology at James Cook University. (Youtube Video)
Coal power and coal export is causing climate change
Early this year I reported on the expansion of coal, coal seam gas and port facilities and it's impact on the Great Barrier Reef. Greenpeace had issued a report Boom Goes the Reef: Australia's coal export boom and the industrialisation of the Great Barrier Reef (PDF), in which they highlight the massive expansion of liquified gas and coal port facilities underway and planned and the massive increase in ship traffic through the World Heritage Area this will generate.
Coal exported from Queensland ports in 2011 amounted to 156 million tonnes. The expansions planned will result in the export of 944 million tonnes per year by 2020. While 2011 saw 1,722 coal ship movements, by 2020 this could expand to 10,150 all passing through the Great Barrier Reef marine park. Driving these coal port expansions are new coal mines planned or being expanded in the Bowen Basin, Galilee Basin and Laura Basin.
Increase in bulk carriers through the Great Barrier Reef is likely to cause increasing impact and damage on the reef. There are now on average two major shipping incidents being reported every year. Groundings and subsequent pollution from incidents like the grounding of the Chinese bulk coal carrier the Shen Neng 1 in 2010 will have a cumulative impact.
Australia's continued reliance on coal power for electricity and expansion of it's coal export industry is contributing to inexorably driving the world past tipping points such as the disintegration of Arctic summer sea ice, melting of the Greenland ice sheet, and the start of destabilisation of the West Antarctic Ice sheet. We are living on borrowed time and unless we can reverse some of the damage we are doing we are making a more hellish and inhospitable world to be lived in by our children and future generations.
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:
By the end of this century:
Other stresses faced by corals and reefs:
Future impacts on coral reefs:
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.
Takver is a citizen journalist from Melbourne Australia who has been writing on climate change, science and protests since 2004.