Sea level rise: Climate change is eating away at maritime borders

Corals particularly suffer from the consequences of climate change. That’s why it’s not just the famous Great Barrier Reef that is at risk. A quarter of Australia’s coral islands are also in danger, a recent study shows. This could have serious implications for the country’s maritime borders and become a geopolitical problem.

Coral islands are usually only a few meters above sea level. The land masses formed by sediments from the calcareous skeletons of corals, mussels and snails are, like the corals themselves, vulnerable constructs. But coral islands are also home to millions of people. They are of crucial ecological, economic, social and geopolitical importance, especially for the smaller island states in the Pacific.

The islands also play an important role for countries with sea coasts for legal reasons. “Coral islands support and extend the legal maritime jurisdictions of coastal countries over large areas of the sea,” explained Tommy Fellowes from the University of Sydney.

Islands are in danger of disappearing

His home country Australia also relies on its coral islands. Several hundred lie off the coasts of the fifth continent. Fellowes and his team now have 56 of them for one Study investigated, which was published in the journal “Science of the Total Environment”. “We have quantified the risks to Australia’s coral islands for the first time,” reported Fellowes. The islands were divided into five risk categories, from low to very high risk.

The researchers found that all of the islands examined are exposed to a certain degree of climate risk. A quarter are even at risk of being completely wiped out by the effects of climate change. According to the scientists, three small coral islands in Western Australia on the reefs Scott, Clerke and Imperieuse are particularly at risk.

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Fellowes explains that the low-lying coral islands and the associated reef ecosystems are threatened by several consequences of climate change: In addition to rising sea levels, these include higher sea temperatures themselves, increasing storms and ocean acidification. The results of the study show that there is an urgent need for action to save the islands, said the researcher. Many of the islands mark and extend the boundaries of Australia’s maritime territory through their position. These maritime areas have critical resources, including fisheries and mineral exploration. The islands are therefore important for the local communities, but they are also of geopolitical and strategic importance. The loss of the islands could potentially have an impact on Australia’s maritime control area.

Reefs die at 1.5 degrees of warming

According to Frances Anggadi, a legal expert at the University of Wollongong, for coral islands the outer low water line of the reef is used as the legal basis for establishing marine zones. In an earlier study by the University of Sydney, she said the potential loss of marine areas due to changes in this line due to climate change could be “a serious problem for nations like Kiribati, but also for larger countries like Australia.” Because they rely on reefs and islands to maintain their claims. In the Australian case, the islands delimit about 15 percent or 1.2 million square kilometers of Australia’s maritime zone in the Indian and Pacific Oceans and, to the north, in the Torres Strait.

But climate change isn’t just affecting Australia’s coral islands. The coral reefs themselves are also suffering from the consequences of global warming. As sea temperatures have risen worldwide as a result of climate change, it is estimated that around 50 percent of reefs have already died. Sea temperatures that are too high lead to coral bleaching, while bleaching that lasts too long or too often leads to the complete death of the coral. Estimates suggest that even if global warming reaches 1.5 degrees Celsius above pre-industrial levels, 70 to 90 percent of the world’s corals will disappear. For example, the health of the world’s largest coral reef, Australia’s Great Barrier Reef, has been fragile for years.

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