By Mary O’KEEFE

A report released this month by the Australian Institute of Marine Science found substantial impacts from a 2024 mass coral bleaching.

The report covered the reefs in the northern, central and southern Great Barrier Reef (GBR) following the 2024 mass coral bleaching event. 

“The 2024 mass coral bleaching event was the fifth mass coral bleaching event on the GBR since 2016 and was part of an ongoing (fourth) global event that began on Northern Hemisphere reefs in 2023 and was declared by the National Oceanic and Atmospheric Administration (NOAA) and the International Coral Reef Initiative (ICRI) in April 2024. The 2024 event had the largest spatial footprint ever recorded on the GBR with high to extreme bleaching prevalence observed across all three regions of the GBR,” according to the Australian Institute. 

There were several factors contributing to the bleaching including the crown-of-thorns starfish that was detected on 27 surveyed reefs in 2025 and above average water temperatures that occurred on GBR.

There was not severe bleaching on all of the GBR but the areas that were affected saw the largest decline of coral in recorded history. The cause was reportedly a marine heatwave that bleached areas of hard coral. 

In 2024 the reef has its worst summer on record after a rare global mass coral bleaching event. Water temperatures rose and the El Niño pattern did not help. The report stated the reef lost between a quarter and a third of its hard coral cover over three main areas.

In some areas about 70% of the living coral was lost. 

Coral does recover; however, according to the report, “these results demonstrate that the GBR is under severe cumulative pressure and that coral cover gains in recent years were reversed over the 2024 summer. This reversal was anticipated last year, as many coral species are highly vulnerable to elevated heat stress, wave damage and crown-of-thorns starfish predation, all of which continue to impact the GBR.”

Many of us may have not, or may never, dive among this colorful coral in the GBR but the loss does matter. It matters directly to those businesses that depend on the tourists who come to snorkel among the coral but it goes beyond that – as bleached corals die, and as the report found, it is difficult for coral to return. 

Coral reefs support some of the most biodiverse ecosystems on the planet. Thousands of marine animals depend on coral reefs for survival, including some species of sea turtles, fish, crabs, shrimp, jellyfish, sea birds, starfish and more, according to World Wildlife Fund (WWF). 

“Coral bleaching impacts peoples’ livelihoods, food security and safety. Coral reefs are natural barriers that absorb the force of waves and storm surges, keeping coastal communities safe. Without them, we must rely on manmade seawalls that are expensive, less effective and environmentally damaging to construct. Bleached coral also compounds the overfishing crisis by removing links in the food web and depriving some fish and crustacean species of a place to spawn and develop. Anyone relying on these animals as a primary source of income or protein will be in trouble,” according to WWF. 

So this is why it matters – not just for those who are near the GBR or depend directly on fishing in the area but it also matters to all of us. 

First of all, the bleaching is a “canary in the coal mine” as far as climate change. Corals are some of the planet’s ecosystems most vulnerable to climate change. Coral supports 25% of marine life, which could disappear and that would affect us because it will affect the ocean. We all depend on those items that come from across the ocean in the form of global trade. 

And then there is the weather. 

“Ocean water is constantly evaporating, increasing the temperature and humidity of the surrounding air to form rain and storms that are then carried by trade winds. In fact, almost all rain that falls on land starts off in the ocean,” according to NOAA. 

Earth really is living in the balance – when one part of it is destroyed it does  impact the entire ecosystem. 

We will see a warming trend this week into next with temperatures slightly higher than normal (mid-80s). Highs will be in the upper 80s on Tuesday.