Climate change: 99 percent of Australia's Great Barrier Reef could be wiped out by 2025 - report

All but 1 percent of Australia's Great Barrier Reef could be destroyed within the next four years if the Earth continues tracking at its current rate of warming, a new report has found.

The study - released this week under the title The Risks to Australia of a 3C Warmer World - says between 70 and 99 percent of the corals could be doomed unless "transformative action" is taken to reverse current trends.

Australian Academy of Science researchers explored the risks to Australia's future based on the current global rate of greenhouse gas emissions, and found net-zero emissions by 2050 should be seen as an "absolute minimum" requirement.

They say the target set in the Paris Climate Accord - to limit global warming to just 1.5C - is now "virtually impossible", and that the Great Barrier Reef is doomed if temperatures go beyond that point.

At 1.5C of warming, the reef is set to shrink by 70 to 90 percent, while at 2C, just 1 percent of the corals would remain. Current trends show the Earth is set to surpass the 1.5C mark by 2025.

Projected warming by 2100 under various scenarios.
Projected warming by 2100 under various scenarios. Photo credit: Australian Academy of Science

But there is still hope; researchers found that if temperatures were to stabilise, the surviving corals could expand to cover the reef again. If they were to continue to go up, however, seaweeds would soon take over.

"It's questionable that this would produce the $5 billion in income the reef now produces in tourism," study co-author Professor Ove Hoegh-Guldberg told the Sydney Morning Herald.

The report finds that even if countries meet their Paris Climate Accord pledges on time, Earth is likely to reach average global surface temperatures increases of 3C this century. They say this will have "catastrophic consequences".

"The unprecedented bushfire season in 2019–20 and the mass dying of corals on the Great Barrier Reef demonstrate how rapidly and fundamentally our global environment is changing with only 1.1C of global warming," said Distinguished Professor Lesley Hughes of Macquarie University.

"It's not too late to avoid 3C. We should still be aiming for a stable global temperature below 2C but to get to that point, we must reduce emissions very rapidly - in particular accelerating the energy transition in the next decade.

"This must be one of the most urgent national and international priorities."