The Great Barrier Reef is one of the seven wonders of the natural world.
It is larger than the Great Wall of China and the only living thing on earth visible from space.
The Great Barrier Reef includes over 2,900 reefs, around 940 islands and cays, and stretches 2,300 kms along the Queensland coastline. The Great Barrier Reef Marine Park is 345,000 km2, that's larger than the entire area of the UK and Ireland combined!
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.
Over the past one hundred years, the temperature of sea water in many tropical areas has been rising. For example, the Australian Institute of Marine Science has collated data showing that 2002 was the warmest year for water temperatures off northeast Australia since 1870.
Impacts on the GBR causing bleaching:
Rising water temperatures block the photosynthetic reaction that converts carbon dioxide into sugar. This results in a build-up of products that poison the zooxanthellae, the single-celled plants that live in the tissues of animals. They are dinoflagellates, a group of microscopic plants which are usually found swimming and floating in the sea. Organisms which live like this are called plankton, and those that are plants are called phytoplankton. To save itself, the coral spits out the zooxanthellae and some of its own tissue, leaving the coral a bleached white.
In Australia alone, the 2002 bleaching saw nearly 60 per cent of the reef suffer bleaching and, in the worst areas, 90 per cent of the coral was bleached.
Coral reef bleaching is caused by various anthropogenic and natural variations in the reef environment including sea temperature, solar irradiance, sedimentation, subaerial exposure, inorganic nutrients, freshwater dilution, and epizootics (a disease that appears as new cases in a given animal population, during a given period, at a rate that substantially exceeds what is "expected" based on recent experience). Coral bleaching events have been increasing in both frequency and extent worldwide in the past 20 years.
[Tridacna crocea giant clam. Although in the giant clam family this small clam rarely gets more than 10 centimeters long. This species is normally found in shallow intertidal reef flats where its symbiotic zooxanthellae can get the most sunlight for photosynthesis. ] photo courtesy Wikimedia commons.
Federation of Australian Scientific and Technological Societies told a meeting at the Canberra parliament:
Climate Change Alliance scientists briefed
politicians from all sides (17th Nov) that the reef is facing a bleak future.
The Alliance, which is led by Federation of Australian Scientific and Technological Societies president Ken Baldwin, will warn MPs and senators that the reef is on the frontline of climate change.
Professor Terry Hughes and representatives told the meeting at the Canberra parliament that the future of the reef, and a large chunk of Australia's tourist industry, was under grave threat from rising sea temperatures.
Global carbon emissions must be cut by at least 25 per cent by 2020 to give the Great Barrier Reef a better than 50/50 chance of survival, the alliance of Australia's reef and climate scientists says.
The 13 scientists said even deeper cuts of up to 90 per cent by 2050 would be necessary if the reef were to survive future coral bleaching and coral death caused by rising ocean temperatures.
“We’ve seen the evidence with our own eyes. Climate change is already impacting the Great Barrier Reef,” Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University, said in a briefing to Australian MPs.
Damage to habitat of marine species:
Professor Charlie Veron, Prof. Hoegh-Guldberg, Dr Janice Lough of Centre Of Excellence Coral Reef Studies
and the Australian Institute of Marine Science and colleagues warn in a new scientific paper published in the Marine Pollution Bulletin: 'Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions,' they add. 'Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other (marine) ecosystems.'
Prof Veron told the British Royal Society recently that Australia’s Great Barrier Reef would be on ‘death row’ unless urgent action was taken to stem global carbon emissions.
'We are tracking the IPCC’s worst case scenario. The global CO2 situation, tracked by temperature and sea level rise, is now following the worst case scenario,' he says. 'The people meeting at Copenhagen need to hear this message.'
Prof Hoegh-Guldberg warns 'We are already well above the safe levels for the world’s coral reefs....
'We are already well above the safe levels for the world’s coral reefs. The proposed 450ppm/2 degree target is dangerous for the world’s corals and for the 500 million people who depend on them.'
Prof Veron: "It will cost less than 1 per cent of GDP growth (over the next 50 years) to sort this problem out. In times of war individual countries have devoted anything from 40 to 70 per cent of their GDP to the war effort, so the effort required to cease emitting carbon is far, far smaller. It is completely affordable, completely achievable.
The Solution- emissions reduction:
"The Great Barrier Reef will only survive if greenhouse gas emissions are reduced by at least 25 per cent and even then that only gives it an even money chance,'' Baldwin said.
It has said it would go further, with a 25 per cent cut, if a tough international climate agreement is reached at UN climate talks in Copenhagen in December, but this is looking increasingly unlikely with legally binding targets now off the agenda.
"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," The University of Queensland's Professor Ove Hoegh-Guldberg said.
Other threats to GBR:
Over-fishing is another cause for concern because when parrotfish and large herbivorous fish are removed from reef food webs, it allows an increase in Sargassum algae and cyanobacteria that form large beds over the coral. This blocks off the light to the zooxanthellae algae and affects the resilience of corals. That is, it affects their ability to recover from coral bleaching events.
Tougher regulations on farm chemicals are needed following rain that caused one million megalitres of pollution to spew into the great barrier reef, environmentalists say. Relatively low levels of herbicide residues can reduce the productivity of marine plants and corals. However, the risk of these residues to Great Barrier Reef ecosystems has been poorly quantified due to a lack of large-scale datasets. Elevated herbicide concentrations were particularly associated with sugar cane cultivation in the adjacent catchment.
5% reduction in CO2 is not enough:
Australia is one of the world's biggest CO2 emitters per capita, but has only pledged to cut its emissions by five per cent from 2000 levels by 2020. The UN Intergovernmental Panel on Climate Change has concluded that the Great Barrier Reef could be "functionally extinct" within decades, with deadly coral bleaching likely to be an annual occurrence by 2030.
Our environmental “capital” has intrinsic, financial, ecological, environmental and socials value, but without an exact dollar value, it is easily dismissed in the quest for industrialisation, growth, profits and exports. The GBR is an area of great beauty, complexity and mystery. We need to understand the massive stresses our cities and industries are placing on these dynamic and fragile ecosystems.
If the environmental cost of population growth and a developed economy is the loss of our natural heritage and world-famous resources, then the growth mentality of our leaders and economists needs to change with the changing environment.