A section of the Great Barrier Reef, captured by Copernicus Sentinel data (2017), processed by ESA, CC BY-SA 3.0 IGO. (CLICK TO ENLARGE)
Extending more than 2,000 kilometres and covering an area of some 350,000 square kilometres, the Great Barrier Reef is the planet’s biggest single structure made by living organisms, called coral polyps.
Despite its name, it is not a single reef but contains nearly 3,000 different reefs. The reef is home to over 1,500 tropical fish species, 400 types of coral, more than 200 species of bird, 5,000 species of mollusc, 500 species of seaweed and six species of sea turtle. It is also a breeding area for humpback whales. In recognition of its significance, the reef was made a UNESCO World Heritage Site in 1981.
Coral reefs worldwide are increasingly under threat from coral bleaching, and this is especially true in the Great Barrier Reef. Bleaching occurs when algae living in the corals’ tissues, which capture the Sun’s energy and are essential to coral survival, are expelled due to high water temperatures. The whitening coral may die, with subsequent effects on the reef ecosystems and related industries.
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The corals of the Great Barrier Reef have now suffered two bleaching events in successive years, to the point that severe coral bleaching has affected two thirds of the entire reef. Experts are increasingly concerned about the capacity for the reef to survive under the increased threat of climate change. In July 2017 the World Heritage Committee (WHC) decided not to include it in the UNESCO ‘in danger’ list, at the dismay of scientists and environmental groups worldwide. The WHC did state it still had concerns about water quality targets and land clearing laws in Queensland.
This nadir true-color image was acquired by the MISR instrument on August 26, 2000 (Terra orbit 3679), and shows part of the southern portion of the reef adjacent to the central Queensland coast. NASA/GSFC/LaRC/JPL, MISR Team
In 2016, NASA began the three-year mission known as COral Reef Airborne Laboratory (CORAL) to thoroughly survey a portion of the world’s coral reefs, including The Great Barrier Reef, Palau, the Mariana Islands and Hawaii. The aim of the mission is to assess the condition of these threatened ecosystems and understand their relation to the environment, including physical, chemical and human factors.
CORAL is using advanced airborne instruments, including the Portable Remote Imaging Spectrometer (PRISM), and in-water measurements. With new understanding of reef condition, the future—and indeed the fate—of ecosystems like the Great Barrier Reef can be predicted. The results of CORAL are yet to be released.
