Coral catastrophe: Mass bleaching threatens marine ecosystems
Already, 84% of coral reefs are affected by bleaching. Scientists are raising the alarm that the extinction of these organisms will have significant consequences, resulting in a decline in biodiversity. Their disappearance may reduce the ocean's ability to absorb CO₂, accelerating climate change.
Coral reefs are already over 84% affected by bleaching caused by thermal stress. This is an unprecedented situation, primarily driven by human activity, which could lead to the mass extinction of these crucial ecosystems.
The level of coral reef bleaching is currently alarming and unprecedented. In 2024, the fourth global mass bleaching of coral reefs in recorded history was observed (following events in 1998, 2010, and 2015–2017), as announced by NOAA (the U.S. National Oceanic and Atmospheric Administration).
Climate warming is lethal for ecosystems
According to Science Alert, corals are affected by thermal stress due to the rising temperature of ocean waters. Reefs expel the algae, which serve as their food, leading to the loss of their vibrant colours. NOAA indicates that conditions in some regions are so extreme that they could lead to the near-total death of reefs. Melanie McField from the Healthy Reefs for Healthy People initiative emphasizes that even the more resilient corals are beginning to die.
As a result of thermal stress, corals reject the symbiotic algae known as zooxanthellae. These microscopic algae provide corals with most of their energy through photosynthesis and give them their colour. When the water temperature rises by even 1–2°C above the norm, the algae function improperly, forcing the coral to expel them. Consequently, the coral's tissue becomes transparent, revealing the white calcareous skeleton underneath. If conditions do not improve, the coral is deprived of its energy source and dies.
Coral reefs are crucial for marine life and millions of people living in coastal communities. In developing regions, many communities depend on coral reefs for food, employment, and security. Since the 1950s, live coral cover has been halved due to climate change and environmental destruction. With a temperature increase of 1.5°C, 70-90% of reefs may disappear, a potential disaster for both people and the planet.
The impact of fossil fuel emissions on coral die-off
Coral reefs are home to about 25% of all marine species. Their loss could result in the death or migration of many organisms. Oceans store 90% of the excess heat caused by burning fossil fuels. Climate warming is advancing rapidly and is one of the most visible effects of human activity on Earth, with the average global temperature already having risen by over 1.1°C compared to the pre-industrial era.
