Sustainability Corner: Coral reefs and mass bleaching events – The Lamron

Global Coral Bleaching Events and their Impact on Sustainable Development Goal 14 (Life Below Water)

2025 Mass Bleaching Event on the Great Barrier Reef

The Australian Institute of Marine Science (AIMS) has confirmed that 2025 marks another mass coral bleaching event for the Great Barrier Reef. This occurrence is particularly alarming as it represents the second consecutive year of mass bleaching, a development that severely threatens marine biodiversity and undermines the objectives of SDG 14 (Life Below Water). The phenomenon, as defined by the National Oceanic and Atmospheric Administration (NOAA), occurs when elevated water temperatures cause corals to expel the symbiotic algae (zooxanthellae) in their tissues, turning them white. While not immediately fatal, this process leaves the coral vulnerable to starvation and disease, potentially leading to widespread mortality and the degradation of entire reef ecosystems.

Historical Context and Global Scale

The increasing frequency of these events poses a critical challenge to the conservation and sustainable use of marine resources. AIMS has monitored the Great Barrier Reef for 40 years, documenting major mass bleaching events that demonstrate an accelerating trend.

• 1998
• 2002
• 2016
• 2017
• 2020
• 2022
• 2024
• 2025

This issue is global in scope. NOAA has confirmed the fourth global mass bleaching event, occurring from January 2023 to September 2025. This event has subjected 84.4% of the world’s coral reef areas to heat stress, with bleaching confirmed in at least 83 countries and territories, representing a significant setback for achieving the targets of SDG 14 on a global scale.

Climate Change as the Primary Driver: A Challenge to SDG 13 (Climate Action)

Identified Causes and Overarching Threat

The AIMS Summer of 2024-25 report identifies several factors contributing to reef degradation during bleaching events. However, it unequivocally states that climate change is the principal threat, directly linking the health of marine ecosystems to the urgent need for climate action as outlined in SDG 13.

1. Primary Threat: Climate Change (influencing ocean temperature, pH, and currents).
2. Secondary Stressors:
   • Elevated sea surface temperatures
   • Cyclones
   • Rainfall and associated runoff
   • Invasive species (e.g., crown-of-thorns starfish)

Exceeding Global Tipping Points

The Global Tipping Points Report 2025 corroborates these findings, stating that the world has entered a “new climate reality” where global warming is projected to soon exceed the 1.5°C threshold. The report warns that damaging ecological tipping points are already being crossed, with catastrophic impacts on nature and societies. This reality underscores the failure to meet the targets of SDG 13 and highlights the severe consequences for marine ecosystems, which are vital for global environmental stability.

A Call for Accelerated Action in Line with Sustainable Development Goals

Recommended Mitigation and Adaptation Strategies

To address the escalating crisis of coral bleaching, a multi-faceted approach aligned with several Sustainable Development Goals is required. The consensus among scientific bodies is that incremental change is no longer sufficient. The following actions are imperative:

1. Accelerate Climate Action (SDG 13): Radically accelerate efforts to eliminate greenhouse gas emissions to address the root cause of ocean warming.
2. Protect and Restore Marine Ecosystems (SDG 14): Reduce local stressors such as coastal pollution and runoff, establish and enforce marine protected areas, and actively support reef restoration efforts.
3. Invest in Research and Innovation (SDG 9): Increase investment in scientific research that helps corals adapt to rising temperatures and improves conservation strategies.
4. Strengthen Governance and Partnerships (SDG 17): Implement governance structures that can respond to the climate reality and foster global partnerships between governments, scientific institutions, and civil society to coordinate effective action.

Conclusion: The Imperative for Global Partnership

The continued degradation of global coral reefs is a direct indicator of the profound impact of human-induced climate change. Protecting these vital ecosystems, which support immense biodiversity and coastal communities, is impossible without decisive and immediate action on climate change. The successful achievement of SDG 14 (Life Below Water) is inextricably linked to the robust implementation of SDG 13 (Climate Action) and strengthened global cooperation under SDG 17 (Partnerships for the Goals). Failure to act risks irreversible damage to marine environments and the essential services they provide to humanity.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

1. SDG 14: Life Below Water

   This is the most central SDG addressed in the article. The entire text focuses on the degradation of marine ecosystems, specifically the mass bleaching of coral reefs like the Great Barrier Reef. It discusses the causes (warming water), the impact on marine life (“disrupts ecosystems and contributes to the growing issue of fish species dying out”), and the need for protective measures like “establishing marine protected areas” and “reef restoration efforts.”

2. SDG 13: Climate Action

   The article explicitly identifies climate change as the primary driver of coral bleaching. It states, “Climate change remains the greatest threat to the Reef” and links the phenomenon to “elevated temperatures” and “changes to the Earth’s climate.” The call to action is focused on climate mitigation, urging that “climate action must accelerate radically to eliminate greenhouse gas emissions.”

3. SDG 15: Life on Land

   While the focus is on marine life, the article connects the issue to broader ecological health and biodiversity. It mentions that when corals die, “entire reef ecosystems, on which people and wildlife depend, deteriorate.” The call to “regenerate nature” and reduce “non-climate stressors of ecosystems” applies to both marine and terrestrial environments, highlighting the interconnectedness of global ecosystems and the threat of biodiversity loss, such as “fish species dying out.”

2. What specific targets under those SDGs can be identified based on the article’s content?

• SDG 14: Life Below Water

  • Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds. The article supports this by advocating for “limiting local stressors like pollution” and “reducing coastal runoff.”
  • Target 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts. This is directly addressed through the discussion of the “widespread mortality” of coral reefs and the need for “reef restoration efforts” and protection to prevent ecosystem deterioration.
  • Target 14.5: By 2020, conserve at least 10 per cent of coastal and marine areas. The article explicitly mentions the strategy of “establishing marine protected areas” as a way to protect coral reefs.
  • Target 14.a: Increase scientific knowledge, develop research capacity. The article highlights the work of organizations like the Australian Institute of Marine Science (AIMS) and the National Oceanic and Atmospheric Administration (NOAA), which have spent decades “monitoring the Great Barrier Reef” and conducting “expansive reports and overhead surveys.” It also calls for “investing in research that helps corals adapt to rising temperatures.”

• SDG 13: Climate Action

  • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards. Coral bleaching is presented as a direct climate-related hazard. The article discusses the need to support “reef restoration efforts” and invest in research to help corals “adapt to rising temperatures,” which are measures to build resilience.
  • Target 13.2: Integrate climate change measures into national policies, strategies and planning. The article stresses that “Governance has to change” and urges readers to “demand action from our representatives” to “eliminate greenhouse gas emissions,” which points directly to integrating climate action into policy.

• SDG 15: Life on Land

  • Target 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and, by 2020, protect and prevent the extinction of threatened species. The article describes the death of coral reefs as a loss of critical habitat, which leads to the “growing issue of fish species dying out,” directly referencing biodiversity loss.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article mentions or implies several indicators:

• Percentage of coral reef area affected by bleaching: The article provides a specific metric from NOAA, stating that “heat stress has impacted 84.4% of the world’s coral reef area.” This serves as a direct indicator for the health of marine ecosystems (Target 14.2).
• Frequency of mass bleaching events: The article lists the years of documented mass bleaching events on the Great Barrier Reef (“1998, 2002, 2016, 2017, 2020, 2022, 2024 and 2025”). The increasing frequency of these events is an indicator of worsening climate impacts (Target 13.1).
• Global temperature increase: The article references the “Global Tipping Points Report 2025,” which states, “Global warming will soon overshoot 1.5°C.” This is a key indicator for climate change (SDG 13).
• Level of greenhouse gas emissions: The call to “eliminate greenhouse gas emissions” implies that the measurement of these emissions is the primary indicator for progress on climate action (Target 13.2).
• Coverage of Marine Protected Areas: The recommendation to establish “marine protected areas” implies that their creation and geographic coverage would be an indicator of conservation efforts (Target 14.5).
• Biodiversity loss metrics: The mention of “fish species dying out” as a consequence of reef degradation implies that fish population counts and species diversity are indicators of ecosystem health and biodiversity loss (Target 15.5).

4. Summary Table of SDGs, Targets, and Indicators

Source: thelamron.com