Is climate change altering maritime borders?

Global warming, acidification and rising sea levels change the size of coral islands

Coral islands and their reefs grow and shrink naturally due to complex biological and physical processes that have not yet been fully understood. Today, climate change is disrupting them further, creating new uncertainties in ocean spaces where States have rights and responsibilities and small island states, because maritime boundaries could be altered.

Scientists, however, argue that a number of technologies and new approaches, along with further research into the behavior of coral reef islands, will help dispel some of the existing uncertainties.

A study by researchers at the University of Sydney, published in Environmental Research Letters, has concluded that the rules for atolls and coral reefs in international law of the sea, which are already complex and subject to interpretation due to their changing nature, will come under increased pressure as sea levels rise and ocean acidification disrupts reef integrity.

“It’s a perfect storm that is bringing instability and uncertainty to what are already difficult boundaries to determine with great precision,” said Thomas Fellowes, a postdoctoral research associate in the University of Sydney’s School of Geosciences and lead author of the study.

“There are also geopolitical consequences. Coral reef islands are the legal basis for many large maritime areas. So the climate disruptions we’re already seeing, and those we’ll see in the coming decades, can have a substantial impact not just for small island states, but on hotly contested border disputes in places like the South China Sea.”

CONCERN IN SEVERAL NATIONS

A treaty signed by 167 nations and almost universally recognized governs everything from territorial seas, up to 12 nautical miles from a reef’s coastline or low tide line, to exclusive economic zones of up to 200 nautical miles. It also codifies the rules for freedom of navigation and allows nations to exploit, conserve and regulate resources in their territorial waters.

“On coral islands, the outer ‘low tide line’ of the reef is used as a legal baseline for establishing maritime zones,” said Frances Anggadi, a student at the University of Sydney.

“The potential loss of maritime areas due to changes in reef baselines due to climate change is a serious concern for nations like Kiribati, as well as larger ones like Australia, which rely on reefs and islands to maintain their claims.”

There is still no clear agreement on whether changes in the structural integrity of coral reef islands due to climate will lead to legal vulnerabilities. “Maybe not, and that’s what many Pacific island countries believe. What is clear is that a more detailed understanding of the behavior of coral reef islands is needed, along with a rethinking of legal norms,” says Fellowes.

“Coral reefs are vulnerable, they only thrive within a specific range of biophysical, oceanic and climatic conditions. But changes in sedimentation due to climate change may increase (the surface) of coral islands and strengthen some maritime claims. It’s not entirely clear that there will be only losers,” he says.

CORAL REEFS IN DANGER

The researchers argue that one solution is to define reef baselines with geographic coordinates like GPS or remote sensing approaches like satellite bathymetry. Another possibility is to “better understand how climate change will affect the habitability of the island, as maintaining human habitation or economic life in one place is another way to establish a viable claim under the treaty.”

But for these approaches to work, “more data on each coral reef island system is needed to more accurately delineate the true extent of existing claims and better understand what aspects of climate change might affect them in the future,” the University of Sydney said.

According to scientists, there are four ways in which climate change is altering coral reef systems in ways that can affect maritime boundaries: rising sea levels, warming oceans, ocean acidification, and rising storms.

Each of them has an impact on the interconnected biophysical processes that enable the creation, expansion, retreat and overall structural stability of coral reefs and coral islands.

For example, higher temperatures trigger the “expulsion” of symbiotic algae and other invertebrates, which causes coral bleaching, and if enough coral organisms die, it can lead to reef collapse.

In addition, the oceans acidify as they absorb more and more carbon dioxide, which reduces mineral saturation and hinders coral formation. Because reef-building species begin to change their skeletal structures to rely on less carbonate, which jeopardizes the overall integrity of the reef.

Source: Information