“Stop polluting the ocean because once we kill the coral reefs and the rain forest, this earth is toast.”
—Michael Berryman

What is the world’s biggest single structure made by living organisms? So big that it can be seen from space? Surprise, surprise: it’s the Great Barrier Reef, the world’s largest coral reef system. It’s made up of more than 2,900 individual reefs and 900 islands, spanning over 2,600 kilometres (1,600 mi) and covering an area of about 344,400 square kilometres (133,000 sq mi). It’s located in the Coral Sea, off the coast of Queensland, Australia, in the northeast part of the continent.

Coral reefs are amazing structures. Made of and built by billions of tiny coral polyps, they support a wide diversity of life. Arguably the world’s most beautiful example, the Great Barrier Reef has received a number of accolades: it was selected as a World Heritage Site in 1981; it has been designated one of the seven natural wonders of the world; and the Queensland National Trust named it a state icon of Queensland.

Sadly, the Great Barrier Reef is losing its greatness. A new study conducted by the Australian Institute of Marine Science (AIMS) in Townsville and the University of Wollongong has revealed that the Great Barrier Reef has lost half of its coral cover over the last 27 years. The loss has been attributed three major sources of harm: storm damage (48 percent), crown-of-thorns starfish (42 percent), and bleaching (10 percent). The study was published in the Proceedings of the National Academy of Sciences earlier this week.

Dr. Peter Doherty, Research Fellow at AIMS stated the following: ”This finding is based on the most comprehensive reef monitoring program in the world. The program started broadscale surveillance of more than 100 reefs in 1985 and from 1993 it has incorporated more detailed annual surveys of 47 reefs. Our researchers have spent more than 2,700 days at sea and we’ve invested in the order of $50 million in this monitoring program.”

If this rate of loss continues, it’s estimated that half of the remaining coral cover will disappear in another decade. It’s been known that coral reefs are at risk from global warming for years. Last year the World Resources Institute found that 75 percent of the world’s reefs are threatened by both climate change and pollution. As ocean temperatures increase and ocean acidity increases, corals die. What remains is their white “skeletons,” known as bleaching.

Interestingly, the effects on coral vary according to region. The hardest hit portion of the Great Barrier Reef is in the south, but the northern region showed no such decline, primarily because it has been spared the devastating storms that are doing so much of the damage.

Dr. Hugh Sweatman, one of the study’s authors, reported “Our data show that the reefs can regain their coral cover after such disturbances, but recovery takes 10-20 years. At present, the intervals between the disturbances are generally too short for full recovery and that’s causing the long-term losses.”

The researchers already see the reality of the situation. We can’t turn off the increasing tropical storms, the warming ocean, or the increasing acidity because global warming isn’t going away anytime soon. In fact, it’s most likely destined to worsen in coming years given our planet’s steady increase in greenhouse gas emissions.

The researchers suggest crown-of-thorns starfish need to be the focus for recovery because it’s the one component we can have some control over. John Gunn, the CEO of AIMS said “The study shows that in the absence of crown-of-thorns, coral cover would increase at 0.89 percent per year, so even with losses due to cyclones and bleaching there should be slow recovery. We at AIMS will be redoubling our efforts to understand the life cycle of [this particular type of starfish] so we can better predict and reduce the periodic population explosions…. It’s already clear that one important factor is water quality, and we plan to explore options for more direct intervention on this native pest.”

The next decade is going to be very telling for our planet. If what most climate scientists believe is correct, we’ll see more and more damage from climate change. Loss of coral will be but one example.