Coral Reefs May Not Be As Vulnerable To Climate Change As Previously Thought

Coral reefs may not be as vulnerable to climate change as previously thought – as long as carbon emissions are reduced, suggests a new study.

Reefs in one part of the Pacific Ocean have likely adjusted to higher ocean temperatures – which could reduce the future bleaching impacts of global warming, say scientists.

The Newcastle University-led study focused on the Pacific Island nation of Palau and has revealed that historic increases in the thermal tolerance of coral reefs are possible.

Researchers say their findings, published in the journal Nature Communications, illustrate how the capacity could reduce future bleaching impacts if global carbon emissions are cut down.

Drawing on decades of field observations, the Newcastle team modeled many possible future coral bleaching trajectories for Palauan reefs, each with a different simulated rate of thermal tolerance enhancement.

They found that if coral thermal tolerance continues to rise throughout the 21st Century at the most-likely historic rate, “significant” reductions in bleaching impacts are possible.

The results affirm the scientific consensus that the severity of future coral bleaching depends on carbon emissions reductions.

The researchers say that high-frequency bleaching can be fully mitigated at some reefs under low-to-middle emissions scenarios where, for example, the Paris Agreement commitments are fulfilled.

But such bleaching impacts are unavoidable under high emissions scenarios where society continues to rely on fossil-fuelled development.

Study lead author Liam Lachs said: “Our study indicates the presence of ecological resilience to climate change, yet also highlights the need to fulfill Paris Agreement commitments to effectively preserve coral reefs.

“We quantified a natural increase in coral thermal tolerance over decadal time scales which can be directly compared to the rate of ocean warming.”

Lachs, a Ph.D. candidate, added: “While our work offers a glimmer of hope, it also emphasizes the need for continued action on reducing carbon emissions to mitigate climate change and secure a future for these vital ecosystems.”

The study was the result of a collaborative visit Lachs undertook in 2021 to work with Professor Simon Donner’s Climate and Coastal Ecosystems Laboratory at the University of British Columbia in Canada.

To survive amid climate change, the researchers say coral communities need to endure progressively more intense and frequent marine heatwaves.

The Newcastle team’s findings reveal that the thermal tolerance of corals in Palau has likely increased at a rate of 0.1 °C per decade since the late 1980s.

The researchers say that the increase suggests that natural mechanisms, such as genetic adaptation or acclimatization of corals or their symbiotic microalgae, could have contributed to the enhancement of coral thermal tolerance.

Produced in association with SWNS Talker