Extensive Coral Bleaching on Record Since 2023: NOAA Report

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Context:

According to recent observation by the National Oceanic and Atmospheric Administration (NOAA) the mass bleaching of coral reefs around the world since February 2023 is now the most extensive on record.

Key Findings:

Fact	Detail
Most Extensive Bleaching Event	Since February 2023, 77% of the world’s coral reef areas have been subjected to bleaching-level heat stress.
NOAA Declaration	NOAA declared the global bleaching event in April 2024, marking the fourth such event since 1998.
Record-Breaking Event	This bleaching event broke the previous record (2014-2017) by more than 11%, affecting 66% of the world's coral reef areas.
Heat Stress Cause	Climate change and record ocean temperatures are the primary causes, along with El Nino warming ocean regions.
Coral Bleaching Mechanism	Coral bleaching happens when corals expel algae from their tissues due to heat stress, making them vulnerable to starvation and disease.
Global Impact	Bleaching has been confirmed in 74 countries, including Palau, Guam, Israel, and is ongoing in the Caribbean and South China Sea.
Economic Importance	Coral reefs provide approximately $2.7 trillion annually in goods and services, crucial for ocean health, fisheries, and tourism.
Tipping Point	Reefs were projected to suffer severe loss at 1.5°C warming, but damage is occurring at 1.3°C.
UN Emergency Session	Scientists are holding a special emergency session on coral reefs at the UN Biodiversity Summit (COP16) in Colombia in response to this event.
Potential Recovery Hope	A La Nina pattern could bring cooler waters, possibly helping coral recovery, but 2024 is on track to be the warmest year on record.

Reference- https://www.sej.org/headlines/global-coral-bleaching-event-expands-now-largest-record

What is coral bleaching?

When corals are under stress, they expel the microscopic algae that live in their tissues. Without these algae, corals' tissues become transparent, exposing their white skeleton. This is called coral bleaching. Bleached corals are not dead, but are more at risk of starvation and disease.

About Coral Reefs

Coral reefs are underwater habitats created by colonies of small aquatic animals called coral polyps. They use calcium and carbonate to build the reefs. Their distinctive colour comes from symbiotic algae – zooxanthellae – that live inside the corals and form their main energy source.

EXAMPLE: According to the UK’s Natural History Museum (NHM), Australia’s Great Barrier Reef is home to 400 types of corals, 1,500 kinds of fish, 4,000 mollusc species and six out of seven types of sea turtles. The Coral Triangle in Southeast Asia is the most biologically diverse ecosystem in the world.

What Causes Coral Bleaching?

Climate change is the biggest threat to coral reefs, and is making marine heatwaves hotter, longer and more frequent.

For example: The US Office for Coastal Management states that the last mass bleaching wave, between 2014 and 2017, encompassed 75% of global reefs.

Marine heatwaves cause coral bleaching.
One of the many impacts of climate change is global warming or global heating. For Example, in nearly 40% of the Great Barrier Reef, hundreds of individual reefs are experiencing either very high (over 60%) or extreme (over 90%) bleaching, mostly in the south of the reef area.
Other impacts for our ocean include an increase in intensity of cyclones, ocean acidification, and extreme weather events.

Despite their beauty and importance, coral reefs around the world are disappearing fast. Water pollution, overfishing and coastal development are taking their toll on coral reefs at the local level, while carbon pollution threatens reefs worldwide and remains their biggest threat.

Record-breaking marine heatwaves are causing mass coral bleaching on the Great Barrier Reef and coral reefs globally.

EXAMPLES: Since 2016 the Great Barrier Reef has suffered five mass bleaching events. In 2024, some regions in the southern reef experienced elevated water temperatures that broke all previous records for the duration of weeks.

In March 2022, 91% of the Reef bleached for the first time during a La Nina weather event, which typically creates cooler, cloudier conditions.

READ ABOUT CAUSES IN DETAIL HERE-

Coral bleaching

Can coral recover from bleaching?

In some instances corals can recover from bleaching. If heat stress is not prolonged and conditions return to normal, corals can regain their algae, return to their natural colours and survive. However prolonged elevated temperatures, such as those seen in the 2024 bleaching, cause more severe and extreme bleaching that increases coral mortality.

If coral is impacted by more than heat stress, like damage from tropical cyclones and floods, and poor water quality, these cumulative impacts can leave coral living in a weakened state.
It can struggle to recover, reproduce and thrive, becoming even more vulnerable to coral diseases and mortality.

It can take decades for coral reefs to fully recover from a bleaching event, so it is vital that these events do not occur frequently.

Continued burning fossil fuels at our current rate then severe bleaching events are likely to hit reefs annually by the middle of the century. This would be devastating for coral reefs as they would have no chance to recover.

What is the scientific outlook?

Scientists tell us that once we hit 1.5C of warming coral reefs will struggle to survive. If we don’t keep 1.5C of global warming within reach this decade, the harsh reality is we will see more mass bleaching events and the rapid decline of our global icon.

In just seven years, our Reef has suffered four severe mass coral bleaching events, faster and more severe than scientists predicted.

Suggestions

100% renewables by 2030,
Commit to an emissions reduction target of 75% by 2030,
Commit to Net Zero by 2035,
Commit to immediately ending the public funding and subsidies of coal, oil and gas,
Commit to no further approval of fossil fuel infrastructure; and no new thermal coal, oil or gas projects.

Global Initiatives

International Coral Reef Initiative launched a blended finance initiative with the Global Fund for Coral Reefs and the UN High-Level Climate Champions. The aim is to mobilize $12 billion to raise the resilience of 125,000 km2 of tropical coral reefs and transition to “blue economy” practices that make sustainable use of the ocean ecosystem.

Protecting the marine environment and developing the blue economy are the focus of the World Economic Forum’s Friends of Ocean Action initiative. It aims to conserve and use marine resources responsibly to enable sustainable development.

Kingdom of Saudi Arabia's Ministry of Economy and Planning, WAVE, a collective action platform powered by the Future Investment Initiative Institute, Ocean Action Agenda and 10 more ecosystem partners to launch the Regenerative Blue Economy Challenge.

National Oceanic and Atmospheric Administration

It is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploration, and managing fishing and protection of marine mammals and endangered species in the US exclusive economic zone.

Headquarters: The agency is part of the United States Department of Commerce and is headquartered in Silver Spring, Maryland.

Reference- https://www.marineconservation.org.au/coral-bleaching/

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PRACTICE QUESTION

Q.Assess the causes and consequences of the global coral bleaching event. Discuss the potential for coral reef restoration and the challenges involved in these efforts. (250 words)

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GLOBAL CORAL BLEACHING EVENT EXPANDS