Experts are warning that the Great Barrier Reef’s coral reef could suffer mass bleaching in January for the fourth year running.  

According to data from the US National Oceanic and Atmospheric Administration, a section of 800 miles of the Great Barrier Reef is likely to undergo a bleaching event by the end of January.

NOAA forecasts also show that by mid-February, areas north of Cairns in Queensland will be at ‘Alert Level 2’ – where both widespread bleaching and significant coral mortality are likely. 

Coral bleaching is more likely in warmer months. This is why Australian scientists have been on alert for the Southern Hemisphere summer.  

According to scientists, coral bleaching caused the death of 30% of Great Barrier Reef’s corals in 2016. It was followed by its third major bleaching event in 2020. 

Bleached coral on the Great Barrier Reef outside Cairns Australia during a mass bleaching event. The Great Barrier Reef has seen five mass bleaching events - 1998, 2002, 2016, 2017 and 2020

A mass bleaching event caused coral to become bleached on the Great Barrier Reef, Australia. There have been five major bleaching events on the Great Barrier Reef – 2016, 2017, 2018, 2020 and 1998.

Great Barrier Reef could face another mass bleaching by end of January, forecast says, US National Oceanic and Atmospheric Administration (NOAA) data shows

According to US National Oceanic and Atmospheric Administration data (NOAA), Great Barrier Reef may face another massive bleaching event by January.


There have been five major bleaching events on Great Barrier Reef – 2016, 2017, 2018, 2020 and 2002. Mass bleaching can occur over tens to hundreds of kilometers (and sometimes even thousands).

They are capable of destroying entire ecosystems and can be a major concern to coral reef scientists and managers. 

According to Australian government scientists, July’s assessment of the Great Barrier Reef showed that despite coral recovery in the past year it remains very poor.  

Rising water temperatures are attributed to human activity, such as burning fossil fuels. Experts believe this is a result of our actions. The warming of the oceans is threatening corals. This leads to coral bleaching as well as acidic water, more disease, and other problems.

Professor Peter Mumby at the University of Queensland told the Guardian that world-famous reef, listed as a World Heritage Site in 1981, is in a critical period for recovery.

But, he stated that NOAA’s forecasts “tends to be quite conservative”, which suggests that the extent of the bleaching events could even be underestimated. 

Professor Mumby explained that “everyone feels a little depressed about the prospect of another bleaching incident.”

Dr Selina Ward, also at the University of Queensland, also said: ‘This Noaa forecast suggests we’re likely to have a bleaching event and it would come earlier in the summer than we would expect.’ 

Scientists believe that a cyclone (or other cool event) will help offset mass bleaching from rising temperatures.  

Corals are more stressed by rising ocean temperatures. They release alga that is found in their bodies, which provides them with up to 90% of their energy. 

This event causes the vibrantly-coloured communities of coral to turn white – an effect called coral bleaching.

Coral bleaching (seen here in the Great Barrier Reef) is thought to have been caused by heat stress due to warmer water temperatures as a result of global climate change

It is believed that coral bleaching, as seen here on the Great Barrier Reef, was caused by heat stress from warmer water temperatures due to global climate change. 

There are decades worth of research on coral protection and climate change.  

Scientists say that coral reefs have been so severely damaged by climate change, decades of research into how to save them might not be relevant anymore.

UK scientists have found that the warming climate has rewritten decades-old knowledge about corals in protected areas known as marine reserve.

This guide has been used to revitalize biodiversity in disturbed regions. 

Learn more: The climate change has transformed tropical coral reefs 

While corals do not die, bleached corals have a greater chance of dying. Climate change is making these events more common. 

Although some coral reefs may be capable of recovering over time, other coral reefs become overwhelmed by seaweed. 

If coral receives its nutrients quickly enough, they can survive bleaching. However, if this is not the case, it could cause death in a matter of days as previous research has shown. 

Over the years repeated coral bleaching caused by warming oceans has led to disruption of marine ecosystems throughout the world. 

This decreases the food supply and shelter available for many of the marine species dependent on coral structures. It also results in biodiversity declines. 

Fortunately, Australia’s climate is currently under the influence of La Niña – the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean.

This is expected to deliver more cloud and rain to the reef’s waters, which would cool temperatures and potentially avoid a bleaching event. 

‘But we have just not seen that yet this summer,’ Dr David Wachenfeld, chief scientist at the Great Barrier Reef Marine Park Authority, told the Guardian.

‘We’re hoping those typical La Niña conditions will kick in. It is crucial to monitor the weather over the coming weeks. 

Australian scientists reported that the Great Barrier Reef experienced its third major bleaching event within five years during the 2019-20 Southern Hemisphere Summer.  

1.036 Reefs have been surveyed from the air. It was found that they were badly affected in their northern, central, and southern regions.  

The ARC Centre of Excellence previously calculated that coral bleaching had affected the Great Barrier Reef’s southern third. 

Bleached coral in French Polynesia during bleaching in 2019, thought to have been caused by heat stress due to warmer water temperatures as a result of global climate change

French Polynesia’s bleached coral was seen during the 2019 bleaching. It is thought that this may have been due to heat stress as a result to higher water temperatures in response to global climate change.

Air surveys revealed the northern, central and southern areas had been hit by coral bleaching during the 2019-20 Southern Hemisphere summer

Air surveys revealed the northern, central and southern areas had been hit by coral bleaching during the 2019-20 Southern Hemisphere summer

One promising development to reduce bleaching  has been scientific attempts to transplant live corals grown in the lab to dying reefs in the ocean.

The new corals from the lab are expected to boost reef recovery and restore it to its healthy condition.

However, these transplanted corals often face low survival rates due to poor planning and site selection based on convenience, according to University of Hawaii Manoa researchers. 

To lure fish into the damaged coral areas, loudspeakers have been used to make ambient sounds from a healthy reef. 

When sea temperature rises, coral expel tiny algae from the ocean. This causes them to become white.

The corals share a special relationship with tiny marine alga called “zooxanthellae”, which live within them and provide food. 

Corals are able to expel colourful algae from the seabed when temperatures rise. They become whiter due to the loss of algae. 

These bleached conditions can persist for as long as six weeks. Corals may recover if temperatures drop and algae return. However, corals that have been severely damaged by bleaching will die and be covered in algae. 

Satellite images can be difficult to tell the difference between dead and healthy corals in either of these cases.

Recent bleaching has resulted in the death of up to 80 percent of corals on some parts of Great Barrier Reef.

These bleaching events are occurring four times as often worldwide than ever before. 

An aerial view of Australia's Great Barrier Reef. The corals of the Great Barrier Reef have undergone two successive bleaching events, in 2016 and earlier this year, raising experts' concerns about the capacity for reefs to survive under global-warming

Aerial view of Australia’s Great Barrier Reef. Two bleaching events have occurred in the Great Barrier Reef corals, one each in 2016 and the other earlier this year. This raises concerns from experts about their ability to survive the global-warming climate.