The Great Barrier Reef is being devastated by yet another mass bleaching event caused by climate change and rising ocean temperature. Scientists confirmed that this is the fourth event in just six years for the world’s largest coral reef system.
This bleaching event is of particular concern, as it is occurring in the same year as a La Niña weather phenomenon. This would typically bring cooler temperatures to Australia.
The Great Barrier Reef is a World Heritage Site. Covering over 300,000 square kilometres, it is the largest living structure on Earth. As well as a natural wonder, it is an economic powerhouse. Annually, the ecosystem contributes more than AUD $6.4 billion to the Australian economy and around 64,000 full-time jobs.
The news comes as UNESCO delegates visit the Reef to assess whether it is ‘in danger’ due to climate change. Scientists recommended this in 2021. However, Australia managed to postpone a downgrade of the World Heritage site after lobbying led to UNESCO delaying the decision to this year.
Devastation for Australia’s natural wonder
This unprecedented sixth mass bleaching event is causing serious concern for scientists. “The frequency of concerning heat stress is happening faster than we ever thought it would”, said Dr Neal Cantin from the Australian Institute of Marine Science, who led the aerial surveillance work with the Great Barrier Reef Marine Park Authority. “The fact it’s impacting such a large area of the marine park, during a La Nina year, is a clear sign of climate change-driven ocean warming.”
Dr Cantin says that it is reasonable to expect another four bleaching events in the seven summers ahead. “We expect these trends to continue and only accelerate in the future.”
The excess heat absorbed by the ocean in 2021 was equivalent to the seven Hiroshima atomic bombs detonating every second, according to a report by Australian climate organisation The Climate Council.
A recent study led by Terry Hughes, a leading expert on the Great Barrier Reef, found that more than 98 per cent of all individual reefs have bleached at least once. The first mass bleaching event to ever be recorded only occurred in 1998. Since then, the reef has experienced events in 2002, 2016, 2017 and 2020, and now, 2022.
What causes corals to bleach?
Corals are living animals, and coral reefs are among the most complex and fascinating marine ecosystems. As the “rainforests of the sea”, they provide precious habitats for thousands of marine species. Around 25 per cent of all fish in the sea rely on coral reefs.
Healthy coral is characterised by its striking bright and vibrant hues. Their colour comes from microscopic algae that live within the coral in a mutually beneficial relationship, helping each other survive.
But, the rising temperature of the ocean caused by human-induced climate change is threatening these precious and delicate coral ecosystems. An increase of just 1°C over four weeks can trigger bleaching. Pollution and ocean acidification are also to blame.
These changes in the ocean environment put corals under stress. As a result, they expel the algae living in their tissues, causing them to turn white. This bleaching does not mean a coral is dead. But losing their algae puts the coral at increased risk of starvation and disease. As it takes years around 10 years for coral to recover from bleaching, repeated events are particularly dangerous.
Global temperature rising
The effects of climate change gravely threaten tropical coral reefs, according to a recent Intergovernmental Panel on Climate Change (IPCC) report. Tropical coral reefs face 70 to 90 per cent declines if global temperatures rise to 1.5°C and will see 99 per cent declines if warming continues to 2°C. Current world emission policies and commitments put the world on course for warming of about 2.3-2.7°C.
Australia’s climate policies are “Highly Insufficient” for limiting warming, according to Climate Action Tracker. If replicated by other countries around the world, it would lead to devastating 3-4°C warming.
The Morrison government has repeatedly come under pressure for failing to address climate change with meaningful policies. Just last month, UN Secretary-General Antonio Guterres condemned Australia as a global “holdout” on the stronger efforts required to cut emissions by 2030.
Limiting rising temperatures would mitigate the damage to Australia’s “irreplaceable natural heritage treasure“. The government must now face up to its responsibilities in tackling climate change by ending fossil fuels and switching to renewable energy. The future of the Great Barrier Reef depends on it.