4th Global Coral Bleaching Event

GS3 – Environment

Context:

The US National Oceanic and Atmospheric Administration (NOAA), along with the International Coral Reef Initiative, has officially confirmed that the world is experiencing its fourth global coral bleaching event.

Currently, around 84% of the world’s coral reefs have been impacted, with mass bleaching observed across at least 83 nations and territories.

About Coral Reefs

• Coral reefs are formed by tiny marine creatures called coral polyps, which extract calcium carbonate from seawater to construct rigid skeletons that build up reef structures.
• Over millennia, these reefs have evolved into intricate ecosystems that, despite covering less than 1% of the ocean floor, support over 25% of all marine species.
• Coral reefs are essential not just for marine biodiversity but also for coastal protection, local economies, and livelihoods through tourism, fishing, and natural defenses against storms.

Understanding Coral Bleaching

• Coral bleaching occurs when corals lose their symbiotic algae (zooxanthellae) and associated pigments, turning them white.
• While bleached corals are still alive initially, they are under extreme stress, making them more susceptible to starvation, diseases, and eventual death.

History of Coral Bleaching Events

• The first two global coral bleaching events took place in 1998 and 2010.
• The third, between 2014 and 2017, saw 68.2% of coral reef areas subjected to heat stress high enough to cause widespread bleaching.

Causes of Coral Bleaching

• Primary Cause: Rising sea temperatures driven by climate change, largely due to human activities, remain the main trigger.
• A rise of just about 1°C above the usual temperature is enough to induce bleaching.
• Other Factors: Events such as unusually low tides, pollution, ocean acidification, cyclones, and extreme weather phenomena can also contribute to coral bleaching.

Impacts of Coral Bleaching

• On Marine Life: Coral reefs are crucial for numerous marine species including fish, jellyfish, and sea turtles, offering shelter, breeding grounds, and protection from predators. Reef degradation could push many already endangered species towards extinction.
• On Humans: Coastal communities depend on coral reefs for food security, storm protection, and income through tourism. The loss of reefs compromises these benefits, threatening billions of dollars generated through reef-related activities annually.

Way Ahead

• Curb Emissions: Reducing greenhouse gas emissions is crucial to slowing down reef loss. Achieving the Paris Agreement targets would greatly benefit coral survival.
• Marine Conservation Zones: Establishing areas where fishing is prohibited and creating marine sanctuaries can aid in reef recovery.
• Promoting Sustainable Tourism: Encouraging the use of reef-safe products, setting eco-tourism standards, and spreading awareness about coral health.
• Reef Restoration Initiatives: Techniques like coral farming and transplantation can help rehabilitate damaged reefs.
• Enhancing Public Awareness: Education campaigns and community engagement are vital to build momentum for reef conservation efforts.