WASHINGTON — Even Australia’s most protected marine habitats are likely to suffer extreme impacts from climate change by 2040. According to a new study, even under today’s optimistic climate scenarios, ocean conditions considered extreme today will become the new normal in Australian waters in just 15 years, increasing threats to thousands of marine species.
At that level of warming, the study also found, the effects will be so widespread that almost none of Australia’s ocean territory will be able to provide “safe havens” to shelter marine life from the brunt of those impacts. Refuge from climate change, in other words, will all but disappear.
Study Highlights and Implications
The study, published in Earth’s Future, AGU’s journal for research on the state of the planet, highlights the vulnerability of marine protected areas (MPAs) in Australia. These areas, which comprise about half of Australia’s seven million square kilometers (2.7 million square miles) of marine estate, are legally designated to conserve biodiversity in vital habitats such as coral reefs, kelp forests, seagrass beds, and mangroves.
Lead author Alice Pidd, a former fisheries researcher now undertaking a PhD in quantitative ecology at the University of the Sunshine Coast, emphasized the challenges these areas face. “When we think about marine protected areas, we might imagine fences or boundaries in the ocean,” she said. “In reality, these boundaries are ethereal and porous to a changing climate.”
“Marine protected areas are important tools in reducing the impacts of human activities such as fishing, shipping, mining, and tourism,” Pidd said. “But they weren’t designed with the realities of climate change in mind, and their location alone won’t protect them from its impacts.”
Research Methodology and Findings
To predict how Australia’s waters would respond to various levels of climate change over the course of this century, researchers fed four different greenhouse gas emissions scenarios into 11 different Earth system models. This effort involved processing several terabytes of data over more than six months. Under all but the most hopeful scenarios, they found that global warming of more than 1.8 degrees Celsius (3.2 degrees Fahrenheit) above preindustrial levels would cause Australian marine climate refugia to almost entirely disappear by 2040.
Rapidly reducing greenhouse gas emissions could allow some refugia to reappear after 2060, Pidd noted, but “we have already crossed several climate tipping points. Biodiversity will need to adapt.”
Past the 1.8 degrees Celsius of warming seen in the lowest-emissions scenario, Australian waters would also experience more extreme conditions than any seen from 1995 to 2014, including higher temperature and acidity, lower oxygen, and more frequent and intense marine heatwaves.
Challenges for Marine Protected Areas
When the team examined impacts specifically on Australia’s MPAs, they found virtually no difference in vulnerability compared to unprotected areas. “The results are unfortunately not surprising,” said co-author David Schoeman, a professor of global change ecology at the University of the Sunshine Coast. “Marine protected areas will be as vulnerable as unprotected ocean areas when faced with rapid warming, oxygen loss, acidification, and heatwaves.”
Traditionally, MPAs have been designed to cover as wide a range of species as possible based on their historical habitats. However, Schoeman pointed out, “the past is no longer a good guide to the future.” This is increasingly true as many species’ ranges migrate across static protected area boundaries in response to climate change.
Future Directions and Conservation Strategies
The study suggests that more climate-smart MPA design might focus on protecting remaining climate refugia, where species may have more time to adapt to changes, or corridors between those refugia to facilitate species relocation as ocean conditions change. Pidd is interested in further research to investigate where these “stepping stone” corridors might be most valuable.
“The key is to protect where biodiversity is likely to be in the future, not just where it is now,” Pidd said.
Australia’s upcoming review of its MPA management in 2028 could be an opportunity to incorporate these considerations into marine conservation planning. However, the team stressed that adaptive measures like these are not enough.
