Global coral bleaching event expands to new countries: scientists May 17, 2024

Corals in Key West, Florida, in 2023 - the world is in the midst of a major coral bleaching incident (Joseph Prezioso)

By AFP - Agence France Presse

Global coral bleaching event expands to new countries: scientists

The massive coral bleaching episode flagged by US authorities last month is expanding and deepening on reefs around the world, scientists warned on Thursday.

Amid record ocean temperatures, coral bleaching has been recorded in 62 countries and territories since February 2023, the US National Oceanic and Atmospheric Administration (NOAA) said - an increase of nine from the warning made in April.

“This event is still growing in size and impact,” said Derek Manzello, coordinator of NOAA's Coral Reef Watch program, at a press conference, adding: “This is not something that would be happening without climate change.”

New coral damage since NOAA's April 15 alert has been recorded in India, Sri Lanka, and the Chagos Islands in the Indian Ocean, Manzello said.

Severe or prolonged thermal stress leads to the death of corals, although there is the possibility of recovery if temperatures drop and other stress factors, such as overfishing and pollution, are reduced.

The consequences of coral bleaching are far-reaching, affecting not only the health of the oceans but also people's livelihoods, food security, and local economies.

The current mass coral bleaching is the fourth recorded worldwide, with three others occurring between 1998 and 2017.

Some 60.5% of the world's reefs have suffered from warm bleaching levels in the last 12 months, a record high, according to NOAA.

The previous widespread global bleaching, which occurred from 2014 to 2017, holds the record for the greatest cumulative impact - for now.

Bleaching could occur even more in the reefs of Asia and Mexico, Belize, the Caribbean, and Florida as the oceans continue to warm during the summer, Manzello said.

So far, the Great Barrier Reef in Australia has been hit by bleaching, which is also affecting corals in Thailand.

- Record temperatures -

There is a 61% chance that 2024 will end up as the hottest year ever recorded on Earth and a 100% chance that it will be one of the five hottest years, said Karin Gleason, chief of the monitoring section at NOAA's National Centers for Environmental Information.

Meanwhile, last month, the world's oceans recorded the warmest April temperatures on record, a record broken every month for the past 13 months.

“The build-up of thermal stress was most extreme and unprecedented in the Atlantic Ocean,” said Manzello.

Understanding the consequences of coral bleaching can take time: in the Caribbean, for example, corals can survive immediate thermal stress and die later due to “disease outbreaks or aggregations of coral predators”, added Manzello.

Last year was the hottest year on record, attributed to a terrible combination of climate change and the El Niño weather pattern.

This year, when the La Nina cooling pattern takes effect by the fall, “my hope is that... we'll start to see the percentage of reef areas affected start to decrease,” said Manzello.

By Lucie AUBOURG

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