Global Coral Reef Bleaching Reaches Record Levels as Oceans Heat Up

Featured & Cover Global Coral Reef Bleaching Reaches Record Levels as Oceans Heat Up

The mass bleaching of coral reefs that began in February 2023 has now become the most widespread on record, according to the National Oceanic and Atmospheric Administration (NOAA). As of now, 77% of the world’s coral reef areas, spanning the Atlantic, Pacific, and Indian Oceans, have been subjected to bleaching-level heat stress. This alarming trend is driven by climate change, which has caused ocean temperatures to soar to record and near-record levels worldwide.

“This event is still increasing in spatial extent and we’ve broken the previous record by more than 11% in about half the amount of time,” NOAA Coral Reef Watch coordinator Derek Manzello told Reuters. “This could potentially have serious ramifications for the ultimate response of these reefs to these bleaching events.”

The NOAA officially declared the global bleaching event in April 2024, marking the fourth such occurrence since 1998. The last record-breaking bleaching event, which occurred from 2014 to 2017, affected nearly 66% of the world’s reef areas. However, this latest event has already surpassed that figure.

Coral bleaching is triggered by the heat stress of warm ocean waters. When exposed to excessive heat, corals expel the algae living in their tissues, which are responsible for their vibrant colors. Without these algae, corals lose their color, becoming pale and vulnerable to starvation and disease. Though bleached corals are not immediately dead, they require cooler ocean temperatures for any chance of recovery.

Previous bleaching events have had devastating consequences. It is estimated that at least 14% of the world’s remaining corals died during the last two global bleaching events. Despite this current mass bleaching being the most widespread on record, affecting reefs in 74 countries and territories, NOAA has not yet declared it the “worst” event in terms of overall impact. The full extent of the damage will not be known until scientists conduct underwater assessments in the coming months and years to count the number of dead corals.

“It seems likely that it is going to be record-breaking in terms of impacts,” said Manzello. “We’ve never had a coral bleaching event this big before.”

The effects of this bleaching event have already been confirmed in several regions over the past six weeks, including Palau, Guam, and Israel. Heat stress also remains dangerously high in the Caribbean and South China Sea. As ocean temperatures remain elevated, there are concerns about the future of the world’s coral reefs.

In response to the growing crisis, scientists have organized a special emergency session on coral reefs. The meeting will be held at the United Nations Convention on Biological Diversity (COP16) summit in Colombia later this month. During this session, world leaders and scientists will discuss strategies to prevent the functional extinction of corals. These discussions will include potential new protections and increased funding for coral conservation efforts.

“The meeting will bring together the global funding community to say we’re still in the fourth bleaching event, these are happening back to back …. What are we going to do about it?” said Emily Darling, who leads the Wildlife Conservation Society’s global coral reef conservation program.

In the past, scientists have projected that coral reefs would be in danger once global warming reached 1.5 degrees Celsius above pre-industrial levels. At this point, they predicted that up to 90% of reefs could be lost. However, the latest bleaching records suggest that coral reefs may have already passed this tipping point, even though the planet has only warmed by 1.3 degrees Celsius so far. If true, this could have severe consequences for ocean ecosystems, subsistence fisheries, and tourism, as coral reefs play a vital role in the global economy.

According to a 2020 estimate by the Global Coral Reef Monitoring Network, coral reefs contribute approximately $2.7 trillion in goods and services each year. This includes their role in protecting coastlines from storms, supporting marine biodiversity, and sustaining fisheries that millions of people rely on for food.

The current bleaching event has been exacerbated by El Niño, a natural climate pattern that can temporarily increase ocean temperatures. El Niño officially ended in May, but its effects have lingered, adding to the heat stress that coral reefs are enduring. Scientists are now watching for the potential onset of La Niña, a climate pattern that typically brings cooler ocean temperatures. Many hope that La Niña could provide a temporary reprieve for coral reefs, allowing them a chance to recover.

However, there are concerns that even La Niña may not be enough to reverse the damage. The year 2024 is on track to be the warmest year ever recorded, and some experts fear that high ocean temperatures may now be the new normal. If this is the case, coral reefs could be facing a future where they are in a near-constant state of bleaching.

Derek Manzello expressed this concern, warning that the world might be entering a period “where we’re more or less in a state of chronic global bleaching.”

As the world grapples with the consequences of climate change, coral reefs are emerging as one of the ecosystems most vulnerable to its effects. The unprecedented scale of this bleaching event highlights the urgent need for action to protect these critical ecosystems. The upcoming emergency session at COP16 will provide an opportunity for world leaders to address the crisis and take concrete steps to prevent further damage to coral reefs. Whether through increased funding, stronger protections, or global cooperation, the future of the world’s coral reefs may depend on the decisions made in the coming months.

In the meantime, scientists will continue to monitor the situation closely, gathering data and assessing the damage caused by the ongoing bleaching. As more regions report the effects of heat stress on their coral reefs, the scale of this crisis is becoming increasingly clear. It is now up to the global community to respond and work together to ensure that coral reefs do not disappear altogether from our oceans.

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