The condition of the Great Barrier Reef will continue to deteriorate, largely due to climate change, and the opportunity to secure its future is fast closing. That is the sobering conclusion of a new comprehensive report on the state of the reef.

The report was released by the Great Barrier Reef Marine Park Authority and confirms what scientists have long known: humanity is destroying the Great Barrier Reef and other reefs around the world because it is failing to curb the greenhouse gas emissions that cause global warming.

Earlier this year I visited parts of the southern Great Barrier Reef where massive coral bleaching and death had just occurred. The sight was devastating. Huge expanses of coral had been bleached a ghostly white, interspersed with bright flashes of pink and blue light: a final, heartbreaking release of coral pigment as the organism made a last desperate attempt to survive. I have since learned that much of this coral has now died.

Anyone who knows anything about coral reefs would have been shocked by what I saw. The largest reef in the world was in very, very bad shape. As I swam, I had in the back of my mind that 2023 would be the hottest year on record. In fact, the Great Barrier Reef is the warmest it has been in at least 400 years.

Unless humanity takes drastic action to halt climate change, we will lose the beautiful, complex reefs that have supported the Earth for thousands of years. As this latest report shows, even governments and officials are now acknowledging this fact.

Don’t worry: the reef is in serious condition

The Great Barrier Reef Outlook 2024 report, released late Friday, is the fourth in a series of five-year reports on the health of the reef.

The institute concluded that warming oceans and severe tropical cyclones are exacerbating other threats, such as the spread of crown-of-thorns starfish, poor water quality and unsustainable fishing.

The report says that the condition of some coral species has improved over the past five years – from “very poor” to “poor.” But we shouldn’t get too excited about this. It does mean that some fast-growing coral species are recovering.

There is no question that the outlook for the reef as a whole remains bleak. As the report states:

While recent recoveries in some ecosystem values ​​show that the reef remains resilient, its ability to tolerate and recover is under threat from rapid climate change.

It is also important to note that the report covers the five years up to December 2023. It does not include the damage caused to the entire reef by massive coral bleaching last summer.

As my colleagues and I recently wrote, the Great Barrier Reef has experienced five massive coral bleaching events in the past nine summers.

Bleaching occurs when corals become so stressed by heat that they expel the tiny algae that live in their tissues. These organisms give corals some of their color and aid in their metabolism. During mild bleaching events, corals can recover. However, during the severe bleaching events that are becoming more common, corals do not survive.

Analyses by others show the mortality in great detail. The left image below shows corals on Lizard Island “fluorescing,” or releasing bright pigments, in March this year. This protective measure aims to limit damage to the remaining microalgae.

The picture on the right, three months later, shows that more than 97% of the same corals have died.

Climate change is not the only threat

According to the report, climate-related disturbances are exacerbating the impacts of other chronic damage to the reef through:

• unsustainable fishing
• pollution
• Sediment runoff
• Crown-of-thorns starfish outbreaks.

Other key findings of the report included:

• Most sea turtle populations have declined
• Species such as seabirds, sharks, rays, dugongs and seagrasses have recovered in some areas, but have stagnated or declined in others.
• Populations of saltwater crocodiles are recovering
• Many species whose populations are declining are on the list of endangered or protected species.

Strong leadership is needed

I first visited the Great Barrier Reef in 1980 as a student and my interest in it has never waned. It is one of those incredible natural wonders that defies description.

The reef’s listing on the World Heritage List is testament to its outstanding global value. Australians love and are proud of this vast and stunning place. The reef supports the livelihoods and wellbeing of many people, including the Traditional Owners who have cared for it for thousands of generations. It sustains us all: economically, culturally and spiritually.

You may see a photo of healthy-looking coral and think the reef must be fine. But I have seen the problem firsthand for many years. The reef is suffering greatly – and every fraction of a degree of global warming worsens the damage.

Humanity must take urgent action to limit global temperature rise. But we are failing. We are failing the Great Barrier Reef and coral reefs around the world.

There was a time when governments and reef managers were unwilling to admit the scale of the problem. I don’t think that is the case today. As the report states:

2024 marks the beginning of a new chapter for the reef. Future warming, already written into the climate system, means further deterioration is inevitable. This is the sobering bill of climate change.

Climate change is a global problem, but Australia is undeniably part of it. If we are to save the Great Barrier Reef, this country cannot export fossil fuels to burn overseas. Tackling this problem requires strong political leadership, from the Prime Minister down.

Humanity has all the facts in front of it. The Earth is in an unprecedented time of rapid change. If we do not respond, we will lose the Great Barrier Reef.