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The picturesque vibrancy of the world’s coral reefs is fading, as vast areas are experiencing widespread bleaching. Recent findings from the International Coral Reef Initiative (ICRI) highlight that a staggering 84 percent of the planet’s reefs are afflicted by this phenomenon, marking it as the “most intense global coral bleaching event ever” recorded.
This alarming statistic surpasses previous coral bleaching events which affected 21 to 68 percent of reefs globally. Nevertheless, experts underscore that the corals are not beyond recovery. With appropriate conservation efforts and a decisive reduction in greenhouse gas emissions, there is hope for these marine ecosystems to bounce back.
Corals, which are small marine creatures dwelling in colonies alongside colorful symbiotic algae, depend on these microorganisms for nutrition. This relationship gives corals their vivid colors. However, they are highly sensitive to temperature changes. When water temperatures rise excessively, the algae release toxic substances, prompting corals to expel them, which results in the loss of color and ultimately leads to what is known as “bleaching.”
This ongoing global bleaching event, now recognized as the fourth significant episode since 1998, began in January 2023. It has manifested across various regions at different times over the last two years, driven by unprecedented ocean temperatures. As declared in April 2024, the event coincided with the hottest recorded year on Earth, during which the average ocean surface temperature reached a record 20.87 degrees Celsius outside polar regions.
WATCH | Coral reefs experiencing mass bleaching event:
Coral reefs experiencing mass bleaching event
The U.S. National Oceanic and Atmospheric Administration has reported that mass coral bleaching impacts every major ocean basin, causing corals around the globe to turn white or die from excessive heat stress.
No End in Sight?
The extension of this bleaching event into a two-year timeframe has led researchers to declare that the world’s reefs have entered “uncharted waters.” Britta Schaffelke from the Australian Institute of Marine Science noted that while corals have historically shown resilience to past severe events, the unprecedented length of this current situation is deeply concerning.
Mark Eakin, a former chief of the Coral Reef Watch at NOAA, expressed reservations about the timeline for recovery. He cautioned that the situation may not revert to a stable state, stating, “We may never see the heat stress that causes bleaching dropping below the threshold that triggers a global event.”
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Researchers have noted troubling trends in regions like the Caribbean, where the onset of bleaching events is occurring earlier than in the past. For example, Valeria Pizarro of the Perry Institute for Marine Science highlighted how current temperatures in her area have reached 30 to 32 degrees Celsius, well above the typical 28 degrees Celsius during peak summer months. This has impacted even the most resilient coral species.
Adding to the urgency, Nicola Smith, an assistant professor at Concordia University, pointed out that projections from the Intergovernmental Panel on Climate Change warn of a potential 70 to 90 percent decline in coral reefs if global temperatures rise by 1.5 degrees Celsius compared to pre-industrial levels. She stresses that the current observable changes are a precursor to what may become a year-round issue, rather than confined to the summer months.
The role of coral reefs extends beyond their beauty; they are crucial habitats for countless marine species. The ICRI emphasizes that approximately a third of all marine life depends on coral reefs, which also support the livelihoods of one billion people worldwide through food sources, tourism, and natural storm protection, contributing an estimated $10 trillion to the global economy.
Not Dead Yet
Despite the dire circumstances, the ICRI holds onto the belief that corals can still survive this century with effective conservation actions and a reduction in greenhouse gas emissions to mitigate ocean warming. Some experts argue that corals can endure and recover from bleaching events if conditions improve.
Melanie McField, the director of Healthy Reefs for Healthy People, remarked that although corals may expel their symbiotic algae and appear lifeless, they can survive for extended periods without immediate death. “It … takes months usually,” she explained, emphasizing the gradual nature of their decline.
Even in a compromised state, other marine organisms such as sponges can thrive alongside the corals. McField cautioned that as coral reefs weaken, they become susceptible to destruction, stating, “When that hurricane comes, it turns into rubble,” which poses a significant risk to communities that rely on these ecosystems for protection and resources.
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According to the ICRI, an increase in investment—by as much as sevenfold—is crucial for effective reef conservation. Strategies such as selective breeding, coral restoration, pollution reduction, and overfishing prevention will be vital to their survival.
While McField noted that current conservation efforts are in their infancy, she stresses the need for greater action. Maintaining the global temperature rise to as little as possible above 1.5 degrees Celsius is essential for giving conservation initiatives a fighting chance to succeed. “You can have all these efforts at 1.5 or 1.6 or 1.7, but probably not 2…. Don’t go above that [or] I’m not sure we’re going to be able to save them,” she warned.
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