Context

• The United States National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch (CRW) and the International Coral Reef Initiative (ICRI) have confirmed the fourth global mass coral bleaching event in 2023–2024.

Key Points

• CRW and ICRI have documented coral bleaching in 53 countries, territories and local economies in five different oceans/marine basins between February 2023 and April 2024.
• This is the second such event in the last 10 years and comes at a time when global oceans have also recorded unprecedented warming in 2023 and 2024.
• The previous incident ran from 2014 to 2017. CRW declares a global mass coral bleaching event only when it records or receives input from all ocean basins experiencing coral bleaching.
•   Hard corals (unlike soft corals which have no shells) are marine animals that have a hard covering.
• Single-celled algae grow on the shell in a symbiotic relationship with coral, giving them their distinctive colour.
• They usually come together to form colonies and structures known as coral reefs that become home to millions of marine animals and plants.

About Coral Bleaching

• About 25 percent of all marine species depend on coral reefs during some part of their life cycle.
• When sea surface temperatures rise, algae on hard corals die. As a result, colourful corals turn white. This process is known as 'coral bleaching'.
• When corals die, all the other marine species that depend on them for shelter, food and other ecosystem services also die.
• That's why coral reefs are under threat from rising sea surface temperatures and widespread marine warming, as well as other factors such as ocean acidification and pollution.
• On an average day in 2023, nearly one-third of the global ocean could be hit by a marine heat wave, causing damage to critical ecosystems and food systems.
• WMO reported on the State of Global Climate 2023 report that by the end of 2023, more than 90 percent of the ocean had experienced heatwave conditions at some point during the year.
• El Niño conditions in the equatorial Pacific Ocean that began in July have exacerbated the general trend of warming over land and oceans that has been occurring due to greenhouse gases accumulating in the atmosphere over the past decade. The ocean warming trend continues into 2024.
• Among long-term patterns, ocean warming and mass coral bleaching are closely linked to the occurrence of El Niño events.

National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch (CRW)

• This coral reef ecosystem provides the world's only global early-warning system of environmental changes.

Function

• To monitor conditions that can lead to coral bleaching, disease, and death.
• Providing real-time information and early warning.
• Using climate forecasts.
• It uses remote sensing and in situ data to operate the decision support system.

Important Facts For Exam

About the International Coral Reef Initiative

• It is a global partnership between nations and organisations attempting to preserve coral reefs and related ecosystems around the world.
• Established: 1994
• Founding members: Eight countries namely; Australia, France, Japan, Jamaica, the Philippines, Sweden, the United Kingdom and the United States.
• It was proclaimed at the first Conference of the Parties to the Convention on Biological Diversity in December 1994.
• Membership: ICRI now has more than 100 members, including India.