Off the northeastern coast of Australia lies one of the natural wonders of the world – the Great Barrier Reef (Figure 1), at approximately 18.5° S 148.5° E. It is one of the world’s most iconic natural wonders, stretching over 2,300 km from Far North Queensland and provides a home to more than 9,000 known species (National Geographic, 2023).

It provides incredible environmental, social, cultural and scientific value, and is recognised on the UNESCO World Heritage List for being a “site of remarkable variety and beauty” (UNESCO World Heritage Centre, n.d.), as evidenced by Figure 2.

Local Impacts
Climate change and anthropogenic factors, however, have and will continue to influence coral reefs in multiple ways, and we already see some devastating consequences of human actions on the Great Barrier Reef.
The first, and perhaps the most visible of these, is the mass coral bleaching caused by climate change as a direct effect of global warming, as seen in Figure 3. Higher ocean temperatures cause healthy coral polyps to expel their symbiotic algae (which provide nutrients and energy) living within them, turning the corals pale white and leaving them to potentially starve and die. In 2016, a third global reef bleaching event was declared due to record ocean temperatures, causing a total shallow-water coral cover loss of nearly 30% (Great Barrier Reef Marine Park Authority, 2017). In March 2024, yet another mass bleaching event was confirmed, with 79% of all surveyed shallow-water reefs undergoing coral bleaching (Cantin et al., 2024).

Secondly, ocean acidification also harms coral reefs. This is caused by a human-induced increase in the atmospheric carbon dioxide concentration, currently at around 420 ppm. Around 30% of this increased carbon dioxide has been absorbed by the ocean, which forms more carbonic acid in the water, making the oceans more acidic. This in turn makes it harder for coral reefs to build their calcium carbonate shells, decreasing their growth rates and diversity (Mollica et al., 2017). This makes them even more vulnerable to other potential threats caused by climate change and humans - for example, Zhao et al. (2021) identified that human-caused nitrogen pollution compounds the effects of climate change, making corals more susceptible to disease and competition from other organisms such as macroalgae.
Lastly, there is an alarmingly large variety of interrelated factors threatening the Great Barrier Reef. Increased frequency and severity of extreme weather events, such as heatwaves and tropical cyclones, is a known consequence of climate change (Great Barrier Reef Marine Park Authority, 2011), which can directly damage already vulnerable coral reef habitats. Lastly, human impacts, such as intensive farming and logging practices, increases nutrient runoff, exacerbating outbreaks of crown-of-thorns starfish, which prey on corals (Risk, 2014).
Adaptation and Mitigation
Generally, there are two widely recognised strategies to help protect and preserve the Great Barrier Reef: (1) reducing the severity of climate change by reducing greenhouse gas emissions and drawing down atmospheric CO2, and/or (2) helping coral reefs adapt and survive the ongoing tumultuous changes.
Within Australia, many organisations are striving to help conserve the Great Barrier Reef and its surrounding habitats, such as the Great Barrier Reef Marine Park Authority and the Australian Institute of Marine Science. Supporting foundations, such as the Great Barrier Reef Foundation, directly support ecosystem rehabilitation via their work in restoring coral reefs and improving conservation technology.
Readers can also take steps to limit their own contributions to climate change. This can include actions to reduce their personal carbon footprint (e.g. taking public transport or cycling instead of driving individual cars, reducing electrical/natural gas usage, reducing meat consumption, etc.) and urging local politicians and decision makers to legislate more systemic changes.
Youth in Australia are advocating for stronger climate action through organisations such as School Strike 4 Climate. In schools, young people are also aiming to make a difference – for example, the Environment & Sustainability Team, which I help organise at my school, is currently conducting an environmental audit of areas where native vegetation can be planted and where energy inefficiency occurs. Previously it has aided the school to transition away from single-use plastics, thereby reducing the school’s overall environmental footprint.
Conclusion
The Great Barrier Reef is doubtless a jewel of our natural ecosystems, but as the work of countless geoscientists and other researchers have shown, it is under an unprecedented threat. However, if the global community moves quickly to tackle climate change and bolster our precious marine ecosystems, we may yet be able to preserve the treasure that is the Great Barrier Reef for generations to come.
References
Cantin, D.N., James, N., Stella, D.J., n.d. Aerial surveys of the 2024 mass coral bleaching event on the Great Barrier Reef.
Climate change | gbrmpa [WWW Document], n.d. URL https://www2.gbrmpa.gov.au/learn/threats/climate-change (accessed 7.3.24).
Coral bleaching events | AIMS [WWW Document], 2024. URL https://www.aims.gov.au/research-topics/environmental-issues/coral-bleaching/coral-bleaching-events (accessed 7.3.24).
Ferrari, R., 2024. Bleached Reef in the Keppel Islands on the Southern Great Barrier Reef [WWW Document]. Australian Institute of Marine Science. URL https://www.aims.gov.au/sites/default/files/2024-04/AIMS000003968_706px_bleaching.jpg (accessed 7.3.24).
Great Barrier Reef - UNESCO World Heritage Centre [WWW Document], n.d. URL https://whc.unesco.org/en/list/154/ (accessed 7.3.24).
Great Barrier Reef Marine Park Authority, 2011. Extreme weather on the Great Barrier Reef (Report). Great Barrier Reef Marine Park Authority.
Great Barrier Reef [WWW Document], n.d. URL https://education.nationalgeographic.org/resource/great-barrier-reef (accessed 7.3.24).
Mollica, N.R., Guo, W., Cohen, A.L., Huang, K.-F., Foster, G.L., Donald, H.K., Solow, A.R., 2018. Ocean acidification affects coral growth by reducing skeletal density. Proceedings of the National Academy of Sciences 115, 1754–1759. https://doi.org/10.1073/pnas.1712806115
NeoGeneric, 2017. English: Locator map for the Great Barrier Reef Marine Park in Australia.
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Risk, M.J., 2014. Assessing the effects of sediments and nutrients on coral reefs. Current Opinion in Environmental Sustainability, Environmental change issues 7, 108–117. https://doi.org/10.1016/j.cosust.2014.01.003
Sheaves, M., Coles, R., Dale, P., Grech, A., Pressey, R.L., Waltham, N.J., 2016. Enhancing the Value and Validity of EIA: Serious Science to Protect Australia’s Great Barrier Reef. Conservation Letters 9, 377–383. https://doi.org/10.1111/conl.12219
Unsplash, 2019. Photo by Francesco Ungaro on Unsplash [WWW Document]. URL https://unsplash.com/photos/corals-under-water-XYMm4LRKZLE (accessed 7.3.24).
Zhao, H., Yuan, M., Strokal, M., Wu, H.C., Liu, X., Murk, A., Kroeze, C., Osinga, R., 2021. Impacts of nitrogen pollution on corals in the context of global climate change and potential strategies to conserve coral reefs. Science of The Total Environment 774, 145017. https://doi.org/10.1016/j.scitotenv.2021.145017
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