Coral Reef Monitor Adds New Alert Levels to Track Soaring Ocean Temperatures


As it happens5:59Coral Reef Monitor Adds New Alert Levels to Track Soaring Ocean Temperatures

Ocean temperatures are rising so dramatically that the organization that monitors threats to coral reefs around the world has added three new alert categories.

Coral Reef Watch is a program run by the U.S. National Oceanic and Atmospheric Administration that uses satellites and computer models to monitor heat risks to reefs.

Marine scientists and conservationists use data from the system to understand the impact of warming temperatures on coral reefs, which are diverse marine ecosystems and a key indicator of ocean health.

“Unfortunately, last year it was so hot in the Caribbean that our pre-existing alert system didn’t really do a very good job reflecting the severity of heat stress,” said Coral Director Derek Manzello. Reef Watch. As it happens host Nil Köksal.

“Through the new alert level system, this allows us to inform (conservation) managers and scientists of the anticipated impacts of these heat stress levels.”

What is coral bleaching?

Coral reefs are lush marine ecosystems that arise around colonies of skeleton-covered invertebrates called stony corals.

Corals get their vibrant colors from the algae that live inside their tissues. But when they are stressed, often due to temperature fluctuations, they expel algae and turn bone white – a phenomenon known as coral bleaching.

Without its algae, coral is extremely vulnerable to disease and starvation. If the algae does not return, the coral will die, turning rich habitats into skeletal graveyards.

Ocean corals of different shapes and sizes, all bleached white
Massive coral bleaching in the Florida Keys in late July 2023. (G. Kolodziej/NOAA)

Coral reefs occupy only about one percent of the ocean floor, Manzello says, but one in four documented marine species interacts with them at some point in its life cycle.

“Coral reefs are the rainforests of the sea,” he said. “As coral reefs die, we lose this immense biodiversity.”

“Risk of almost total mortality”

Since its launch in 2009, Coral Reef Watch has used two alert categories to monitor heat risk to coral reefs: Level 1, which means reefs are at risk of coral bleaching, and Level 2, which indicates the risk of “heat-related mortality”. -sensitive corals.”

But in December 2023 – following a massive summer marine heatwave – the group added three additional alert levels, which he publicly revealed this month.

Level 3 indicates a multi-species mortality risk for corals, Level 4 means more than half of the corals on a reef could die, and Level 5 means “near total mortality risk.”

A color-coded world map, dated February 1, 2024, shows huge areas of ocean in yellow, which a ledger says averages are below "watch." Slightly smaller spots are orange, indicating "Warning." Nestled inside the orange spots are red spots, indicating "Alert level 1." A small patch northeast of Australia is fuchsia for alert level 2. And small spots near Australia, Africa and Central America are dark purple, for alert level 2. alert 5.
Coral Reef Watch’s February 1, 2024 map contains several points labeled Alert Level 5, meaning ocean temperatures pose a potentially catastrophic risk to coral reefs. (

“An alert level 5 condition really represents the most extreme, worst-case scenario that you could expect on a coral reef due to heat stress,” Manzello said.

“This is analogous to a Category 5 cyclone or hurricane in that the impacts of a Warning Level 5 bleaching event are expected to be severe and drastic.”

Before 2023, he says only three cases of warming at this level have been described in the scientific literature.

This is what happened to several reefs during the heatwaves of summer 2023, the effects of which were documented in a NOAA-University of Queensland study published in December.

The Sombrero Reef off the Florida Keys experienced 100% coral mortality in July 2023, according to the Coral Restoration Foundation, based in Florida.

“It was, you know, devastating for people who had spent years of their lives trying to restore these reefs,” Manzello said.

Impacts on humans

Stacy Jupiter, a marine scientist in Fiji for the Wildlife Conservation Society, welcomes the changes to the Coral Reef Watch alert system.

“I believe the changes are necessary to demonstrate that the levels of heat accumulation currently observed around the world are currently relatively higher than the highest alert levels previously issued,” she said in an email to CBC.

While the Wildlife Conservation Society uses the Coral Reef Watch alert system in its research, Jupiter says an increase in heat is just one of many predictors of coral bleaching.

A diver swims near a vibrant and colorful coral reef.
A tourist swims on the Great Barrier Reef off the coast of Australia in 2018. The healthy reefs are colorful and full of life. (Ben Cropp/Great Barrier Reef Marine Park Authority/via Reuters)

Nonetheless, she says the degree of ocean warming in 2023 and 2024 is “unprecedented in modern times” and “is indeed very concerning.”

Some can be explained by The boya natural weather phenomenon that begins in the tropics and is marked by the warming of part of the surface of the Pacific Ocean.

“It’s a little hard to say whether we’ll continue to see the same high ocean temperatures in the years to come, but we can’t ignore that we’re approaching some tipping points in Earth’s critical regulatory systems,” he said. Jupiter declared.

Manzello says much more time and financial investment needs to be devoted to protecting coral reefs, including in the field “assisted evolution,” in which scientists study the genetics of more heat-tolerant coralsand use this information “to raising corals for the future“.

If we don’t find innovative ways to preserve coral reefs, we will all feel the impact, he says.

Coral reefs produce compounds used in medicine, provide habitat for fish that people feed on, are a key part of tourism industries around the world, and protect coastal areas from the impacts of powerful storms.

“For me, coral reefs are the most beautiful natural habitat that exists on planet Earth,” he said.

“The fact that these are dying every year on a global scale, I think it’s really an ecological tragedy that’s unfolding before our eyes.”

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