The Reef Monitor adds new alert levels to keep up with rising ocean temperatures

As it happens5:59The Reef Monitor adds new alert levels to keep up with rising ocean temperatures

Ocean temperatures are rising so much 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 US National Oceanic and Atmospheric Administration that uses satellites and computer models to monitor heat risks to coral reefs.

Marine scientists and environmentalists use the system’s data to understand the impact of rising temperatures on coral reefs, diverse marine ecosystems and a key indicator of ocean health.

“Unfortunately, it was so hot in the Caribbean last year that our pre-existing warning system wasn’t doing a very good job of reflecting the severity of heat stress,” said Derek Manzello, director of Coral Reef Watch. As it happens Host Neil Coxall.

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

What is coral bleaching?

Coral reefs are fertile marine ecosystems that develop around colonies of skeletal-covered invertebrates called hard corals.

Coral gets its bright colors from the algae that live within its tissues. But when they become stressed, often due to temperature fluctuations, they expel algae and turn the bones white – a phenomenon known as coral bleaching.

Without algae, coral is highly vulnerable to disease and starvation. If the algae don’t return, the coral will die, turning rich habitats into graveyards for skeletons.

Ocean corals come in different shapes and sizes, all white
Mass coral bleaching in the Florida Keys in late July 2023. (J. Kolodziej/NOAA)

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

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

“Almost complete risk of death”

Since its first launch in 2009, Coral Reef Watch has used two alert categories to monitor heat risks to coral reefs – Level 1, which means the reef is at risk of coral bleaching, and Level 2, which indicates a risk of “heat death.” – Sensitive coral reefs.”

But in December 2023 – in the wake of a massive summer marine heatwave – the group added three more alert levels, Which was publicly revealed this month.

Level 3 indicates the risk of multiple coral species dying, Level 4 means more than half of the corals on the reef could die, and Level 5 means “risk of almost complete mortality.”

A color-coded map of the world, dated February 1, 2024, shows huge patches of ocean in yellow, under which the ledger indicates the means lie. "He watches." Slightly smaller orange spots indicate this "warning." Inside the orange spots there are red spots indicating this "Alert level 1." A small patch northeast of Australia is in fuchsia for Alert Level 2. Small patches near Australia, Africa and Central America are in dark purple for Alert Level 5.
The Coral Reef Watch map released on February 1, 2024, has several points marked Alert Level 5, meaning ocean temperatures pose a potentially catastrophic risk to coral reefs. (

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

“This is similar to a Category 5 hurricane or hurricane where impacts from a Category 5 bleaching event are expected to be severe and drastic.”

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

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

Sombrero Reef off the Florida Keys saw a 100 percent coral mortality rate in July 2023. According to the Florida-based Coral Restoration Foundation.

“This has been, you know, devastating for people who have spent years of their lives trying to restore these coral reefs,” Manzello said.

Effects on humans

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

“I believe the changes are necessary to demonstrate that the levels of heat accumulation we are now seeing across the world are currently relatively greater than the highest alert levels issued previously,” she told CBC in an email.

While the Wildlife Conservation Society uses Coral Reef Watch’s alert system in its research, Jupiter says the increased heat is crucial. Just one of several predictors of coral bleaching.

A swimmer swims near a vibrant and colorful coral reef.
A tourist swims in the Great Barrier Reef off the coast of Australia in 2018. Healthy coral reefs are colorful and full of life. (Ben Kropp/Great Barrier Reef Marine Authority/via Reuters)

However, it says the degree of ocean warming in 2023 and 2024 was “unprecedented in modern times” and “in fact, very worrying.”

Some of them can be explained by BoyIt is a natural climate pattern that begins in the tropics and is characterized by a warming of part of the surface of the Pacific Ocean.

“It’s a bit difficult to say whether we will continue to see the same high ocean temperatures in the coming years, but we cannot rule out that we are approaching some tipping points in Earth’s bioregulatory systems,” Jupiter said.

Manzello says more time and financial investment is needed in protecting coral reefs, including “Auxiliary evolution,” in which Scientists are studying the genetics of corals that are more heat-tolerantand use that information for Breeding corals for the future“.

He says that if we don’t find innovative ways to preserve coral reefs, we will all feel the impact.

Coral reefs produce compounds used in medicine, provide a habitat for fish that people eat, are a staple of tourism industries around the world and protect coastal areas from the effects of strong storms.

“In my opinion, coral reefs are the most beautiful natural habitats on the planet,” he said.

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

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