According to the United Nations Environment Programme, all the coral reefs the world over support as much as 25% of all marine species despite covering only 0.2% of the total area of the world’s seafloor. The statistic just goes to show just how dense marine life truly is in these small areas—and how prone these reefs are to damage brought about by climate change.
A study published in the journal PLOS Climate appears to prove just how fragile Earth’s marine biodiversity has become thanks to our environmentally-detrimental actions, as it appears that we may only be a 1.5-°C temperature rise away, globally speaking, before we stand to lose most of these natural marine habitats.
The research team that arrived at this startling conclusion is composed of University of Leeds’ Piers Forster and Maria Beger, Texas Tech University’s Anne Stoner, and James Cook University’s Scott Heron. University of Leeds Ph.D. candidate Adele Dixon served as lead author of the paper.
The main contributor to this eventual loss of coral reefs, the authors say, is the rise in average global temperatures. Corals had evolved to live within specific temperature ranges through the millions of years since they appeared on Earth
With human activities contributing to a steady rise in global temperatures and heating the oceans in the process, corals are agitated; as a result, they expel the algae that live within their tissues, which otherwise would have provided them with nutrients via photosynthesis in exchange for shelter. As a result, the corals lose their color and turn white—the color of the coral’s secreted calcium carbonate (CaCO3) skeleton that’s left behind.
Dixon and the team warn the public with their paper that at a 1.5-°C rise in global warming due to climate change—a metric that recent estimates predict we’ll reach by the early 2030s should our climate-damaging effects remain unchanged—the oceans will be hit by so much frequent heat waves that 99% of the world’s coral reefs will be unable to recover, according to the authors’ discussion of their work on The Conversation.
The 99% loss predicted by Dixon and the team is greater than the 70%-90% loss predicted by the Intergovernmental Panel on Climate Change, according to their 2018 report on the matter.
Of course, the disastrous effects of this unfortunate event stretch beyond just the corals and the other animals that call them home. Humans living in coastal communities, who may depend on the variety of fish that live in coral reefs near their shores for livelihoods and sustenance, stand to lose the most should the conundrum be left without a solution.
Additionally, corals need plenty of time to rebuild their internal structures, as they grow very slowly. They also stand to experience even more detrimental effects due to other manmade actions alongside global warming, like pollution and overfishing.
“Global warming of 1.5°C is the lower limit that world leaders aspired to maintain when they signed the Paris agreement in 2015. This target is moving further out of reach. For coral reefs, there is no safe limit to global warming. Given the rate at which the global average temperature is increasing, marine heatwaves are likely to become so frequent that most of the world’s coral reefs will experience intolerable heat stress regularly. Most reefs have already experienced at least one such event this decade,” the authors noted in The Conversation.
The authors note that this will affect even the most resistant of coral species; this means that simply leaving our current activities unabated will not solve the issue, and thus demand more effective measures like cutting greenhouse gas emissions.
References
- Dixon, A., Beger, M., Kalmus, P., & Heron, S. F. (2022, February 1). Safe havens for coral reefs will be almost non-existent at 1.5°C of global warming – new study. The Conversation. http://theconversation.com/safe-havens-for-coral-reefs-will-be-almost-non-existent-at-1-5-c-of-global-warming-new-study-176084
- Dixon, A. M., Forster, P. M., Heron, S. F., Stoner, A. M. K., & Beger, M. (2022). Future loss of local-scale thermal refugia in coral reef ecosystems. PLOS Climate, 1(2), e0000004. https://doi.org/10.1371/journal.pclm.0000004
- ICRI, GCRMN, Australia Institute of Marine Science, & UNEP. (2021, October 1). Status of Coral Reefs of the World 2020. UNEP – UN Environment Programme. http://www.unep.org/resources/status-coral-reefs-world-2020
