The Great Barrier Reef stretches for more than 2,300 kilometers (1,400 miles) off the coast of Queensland, Australia. The lives of the 6,000 marine animal species who call it home are in jeopardy, as a new study has found that warming of the ocean threatens to reduce the reef to a mere 10% of its historic cover. Though the Great Barrier Reef is the largest living structure in the world, the threat extends to other reef systems as well. The research was performed by a team from the National Institute for Mathematical and Biological Synthesis (NIMBios), and the results were published in the journal Ecology. The international collaborative study utilized 10 years’ worth of data from 46 reefs, quantifying the short- and long-term effects on those ecosystems.

In the short term, increasing temperatures and man-made influences pose the largest threat. As the oceans warm due to climate change, more carbon dioxide becomes dissolved in the water, making it more acidic. It also diminishes the concentration of calcium carbonate, which is necessary for the skeletons of coral and shellfish. Human contributions of pollution, destruction from development, and overfishing are compounding the problem, irreparably damaging the reefs. This will lead to a surge in seaweed, which will block sunlight, steal nutrients, and effectively choke the coral out.

"The model indicated that warming of an additional 1-2 degrees Celsius would more than likely lead to large declines in coral cover and overall changes to the community structure," lead author Jennifer Cooper from James Cook University said in a press release. "If our model is correct the Great Barrier Reef will begin to look very different as ocean temperatures increase.”

Looking down the road at long-term effects, the abundance of seaweed will change the environment. Where coral once thrived, soft organisms such as sponges and gorgonians (soft coral) will take over, diminishing biodiversity. 

"Even the massive, remote, and intensely managed Great Barrier Reef is being degraded by human activities. Losing the GBR and other reefs would be a massive blow to marine biodiversity and to the people that depend on healthy reefs for food, tourism, and protection from storms," added senior author John Bruno from the University of North Carolina, Chapel Hill.

The Great Barrier Reef was declared a World Heritage Site in 1981, which should have afforded it enough protection. Unfortunately, the reef’s cover has been reduced by more than half since then, making it a candidate to be added to the List of World Heritage in Danger. This occurs when damage to a World Heritage Site is so severe, the location is in danger of losing its distinction. Essentially, it is a call to arms to save an irreplaceable part of our planet. Though some of the short-term effects could be feasible enough to treat, the Great Barrier Reef—and other reefs around the world—still face incredible odds in the long run. 

The methodology of the study does not only apply to coral reefs, but could explain changes in other environments as well, which will be used by the team in future research.

"The beauty of this study is that the same approach should work for other systems, provided enough data are available,” explained co-author Matthew Spencer from the University of Liverpool. “Our next plan is to use it to model the dynamics of European forests.”