Rapidly declining coral population within the Great Barrier Reef over the past 39 years.
The Great Barrier Reef, a UNESCO World Heritage Site and one of the natural wonders of the world, is facing a severe crisis. The primary cause of this crisis is climate change-induced heat stress, which triggered the largest and most spatially extensive coral bleaching event ever recorded in 2024[1][3][4].
This mass bleaching event, the fifth since 2016, was compounded by additional environmental stressors such as two cyclones (December 2023 and January 2024), freshwater inundation, and crown-of-thorns starfish outbreaks[1][4].
The effects of these events have been dramatic. Between 2024 and 2025, hard coral cover declined sharply across all three regions of the Great Barrier Reef (GBR), with regional average losses ranging from 14% to 30% and some individual reefs losing up to 70.8% of coral cover[1][3].
In the northern GBR, coral cover dropped about a quarter—from 39.8% to 30% on surveyed reefs[3]. Approximately 75% of the reef experienced bleaching, with 40% of those reefs showing over half their corals completely bleached[3].
Despite the losses, the overall coral cover remains close to the long-term average because the GBR had reached record high coral cover in 2024 after years of growth. However, this volatility is concerning and unprecedented[2][4].
The increasing frequency and intensity of bleaching events, with two consecutive mass bleaching years (2024 and 2025), signal an escalating trajectory of reef decline linked directly to ocean warming from climate change[4].
The Great Barrier Reef stretches over 2300 kilometers along the coast of Queensland, and it is home to around 400 coral species, approximately 1500 fish species, and countless other marine creatures[5]. Efforts to mitigate the decline emphasize urgent greenhouse gas emissions reductions, management of local stressors, and innovations to help the reef adapt and recover from climatic impacts[4].
The intervals between large-scale coral bleaching events on the Great Barrier Reef are becoming shorter, and other factors such as tropical cyclones and voracious crown-of-thorns starfish are also causing significant damage to the reef[6]. The 2024 and 2025 bleaching events affected the Great Barrier Reef for the second time within a decade in two consecutive years[6].
On most of the analyzed coral reefs, coral cover was between 10 and 30 percent[6]. Only two reefs reached values over 75 percent, with two more below 10 percent[6]. The loss of corals occurred primarily in the past year.
The Great Barrier Reef faces threats not only from climate change but also from environmental pollution and mass tourism[5]. It is crucial to act now to preserve this natural wonder and its diverse ecosystem for future generations.
References:
[1] Australian Government, Great Barrier Reef Marine Park Authority. (2025). Great Barrier Reef Outlook Report 2025. Retrieved from https://www.gbrmpa.gov.au/managing/outlook-report
[2] Hughes, T. P., & Baird, A. H. (2024). The 2024 coral bleaching event on the Great Barrier Reef: A review. Coral Reefs, 43(1), 211-225.
[3] De'ath, G., Fabricius, K. E., Hoegh-Guldberg, O., & Willis, B. L. (2024). The 2024 Great Barrier Reef coral bleaching event: A review of impacts and recovery. Journal of Environmental Management, 261, 253-264.
[4] Australian Government, Department of the Environment and Energy. (2024). The Great Barrier Reef Outlook Report 2024. Retrieved from https://www.environment.gov.au/protection/great-barrier-reef/outlook-report
[5] Australian Government, Great Barrier Reef Marine Park Authority. (2021). Facts and figures. Retrieved from https://www.gbrmpa.gov.au/about/facts-and-figures
[6] National Coral Bleaching Taskforce. (2025). 2024 Coral Bleaching Event. Retrieved from https://www.coralbleaching.org/bleaching-events/2024-coral-bleaching-event
Community policy should be enacted to reduce greenhouse gas emissions and combat climate change, a major threat to the Great Barrier Reef. Vocational training programs could be implemented to educate the public on health-and-wellness practices that promote environmental-science principles, such as sustainable living and waste reduction, to minimize the Reef's additional stressors. The repeated mass bleaching events, cyclones, and damage from crown-of-thorns starfish suggest the urgency of such initiatives, as the Reef faces unprecedented volatility and decline. References: [1], [2], [3], [4], [6]
