Assessing the impact of climate change on coral reefs in the Great Barrier Reef.

Posted: May 31st, 2023

Assessing the impact of climate change on coral reefs in the Great Barrier Reef.
The Impact of Climate Change on Coral Reefs in the Great Barrier Reef

The Great Barrier Reef, the world’s largest coral reef system, is facing unprecedented challenges due to the impacts of climate change. Rising sea temperatures, ocean acidification, and extreme weather events have led to widespread coral bleaching and mortality, threatening the survival of this unique ecosystem (Hughes et al., 2018). This research essay aims to assess the impact of climate change on coral reefs in the Great Barrier Reef, drawing upon recent scholarly literature and data.

Coral Bleaching and Mortality
Coral bleaching occurs when corals expel their symbiotic algae, known as zooxanthellae, in response to environmental stressors such as elevated water temperatures (Heron et al., 2020). The Great Barrier Reef has experienced several mass bleaching events in recent years, with the most severe occurring in 2016 and 2017 (Hughes et al., 2019). These events have led to significant coral mortality, with some reefs experiencing up to 50% loss of live coral cover (Dietzel et al., 2020).

The frequency and severity of coral bleaching events are expected to increase as global temperatures continue to rise (Lough et al., 2018). Climate models predict that the Great Barrier Reef could experience annual bleaching events by 2050 under a high emissions scenario (King et al., 2018). This would have devastating consequences for the reef’s biodiversity and ecosystem services, as well as the tourism and fishing industries that depend on it.

Ocean Acidification
In addition to rising temperatures, climate change is also causing the oceans to become more acidic. As atmospheric carbon dioxide levels increase, more CO2 is absorbed by the oceans, leading to a decrease in pH (Albright et al., 2018). This process, known as ocean acidification, can impair the ability of corals to build their calcium carbonate skeletons, making them more vulnerable to erosion and damage (Eyre et al., 2018).

Studies have shown that ocean acidification can also impact the early life stages of corals, reducing larval settlement and survival (Albright et al., 2018). This could have long-term consequences for the resilience and recovery of coral reefs in the face of other stressors such as bleaching and cyclones.

Cyclones and Extreme Weather Events
Climate change is also expected to increase the frequency and intensity of extreme weather events, such as tropical cyclones (Cheal et al., 2017). The Great Barrier Reef has experienced several severe cyclones in recent years, including Cyclone Debbie in 2017 and Cyclone Yasi in 2011. These events can cause physical damage to coral reefs, as well as increased sedimentation and turbidity, which can smother corals and reduce light availability (Puotinen et al., 2020).

The cumulative impacts of cyclones, bleaching, and ocean acidification can have long-lasting effects on coral reefs. A study by Madin et al. (2018) found that the recovery of coral reefs in the Great Barrier Reef following disturbances has slowed significantly in recent decades, likely due to the increasing frequency and severity of these events.

Implications for Management and Conservation
The impacts of climate change on coral reefs in the Great Barrier Reef have significant implications for management and conservation efforts. While local management actions, such as reducing water pollution and improving fisheries management, can help to increase the resilience of coral reefs, addressing the root cause of climate change will be essential for their long-term survival (Mcleod et al., 2019).

This will require a global effort to reduce greenhouse gas emissions and limit warming to well below 2°C above pre-industrial levels, as outlined in the Paris Agreement (UNFCCC, 2015). Australia, as the custodian of the Great Barrier Reef, has a critical role to play in this effort, both through domestic action and international leadership.

In addition to mitigation efforts, adaptation strategies will also be necessary to help coral reefs cope with the impacts of climate change. This could include measures such as assisted migration of heat-tolerant coral species, the development of coral nurseries to support reef restoration, and the use of marine protected areas to reduce other stressors on coral reefs (Suggett et al., 2017).

Conclusion
The impact of climate change on coral reefs in the Great Barrier Reef is a stark reminder of the urgent need for action to address this global crisis. Rising sea temperatures, ocean acidification, and extreme weather events are already taking a toll on these fragile ecosystems, with potentially catastrophic consequences for their biodiversity and the communities that depend on them.

While local management efforts can help to increase the resilience of coral reefs, ultimately, the fate of the Great Barrier Reef will depend on the success of global efforts to reduce greenhouse gas emissions and limit warming. This will require a concerted effort from governments, businesses, and individuals around the world, as well as continued research and monitoring to inform effective conservation and adaptation strategies.

As the iconic Great Barrier Reef faces an uncertain future, it is clear that the time for action on climate change is now. By working together to address this global challenge, there is still hope that we can secure a future for this remarkable ecosystem and the countless species that call it home.

References:
Albright, R., Takeshita, Y., Koweek, D. A., Ninokawa, A., Wolfe, K., Rivlin, T., Nebuchina, Y., Young, J., & Caldeira, K. (2018). Carbon dioxide addition to coral reef waters suppresses net community calcification. Nature, 555(7697), 516-519. https://doi.org/10.1038/nature25968

Cheal, A. J., MacNeil, M. A., Emslie, M. J., & Sweatman, H. (2017). The threat to coral reefs from more intense cyclones under climate change. Global Change Biology, 23(4), 1511-1524. https://doi.org/10.1111/gcb.13593

Dietzel, A., Bode, M., Connolly, S. R., & Hughes, T. P. (2020). Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef. Proceedings of the Royal Society B: Biological Sciences, 287(1936), 20201432. https://doi.org/10.1098/rspb.2020.1432

Heron, S. F., Eakin, C. M., & Douvere, F. (2020). Impacts of climate change on World Heritage coral reefs: A first global scientific assessment. Paris, France: UNESCO World Heritage Centre.

Hughes, T. P., Anderson, K. D., Connolly, S. R., Heron, S. F., Kerry, J. T., Lough, J. M., Baird, A. H., Baum, J. K., Berumen, M. L., Bridge, T. C., Claar, D. C., Eakin, C. M., Gilmour, J. P., Graham, N. A. J., Harrison, H., Hobbs, J.-P. A., Hoey, A. S., Hoogenboom, M., Lowe, R. J., … Wilson, S. K. (2018). Spatial and temporal patterns of mass bleaching of corals in the Anthropocene. Science, 359(6371), 80-83. https://doi.org/10.1126/science.aan8048