Marine heatwaves, amplified by climate change, have inflicted unprecedented ecological and economic damage worldwide over the past two years, according to a new study published in Nature Climate Change.
The study reveals the catastrophic toll of marine heatwaves observed in the last two years. Scientists report that the number of marine heatwave days during the summers of 2023 and 2024 was 3.5 times higher than in previous years.
This surge, driven by climate change and intensified by the El Niño phenomenon, has caused billions of dollars in losses globally. The research indicates that roughly 10% of the world’s oceans hit record-high temperatures in 2023-2024, with devastating effects on coral reefs, fisheries, and coastal communities.
Researchers warn that without swift action to curb greenhouse gas emissions, these marine heatwaves will only grow more severe. “The sheer number of impacts from marine heatwaves we’ve seen over the past two years is staggering—mass coral bleaching, species popping up in new areas, and a spike in related extreme weather events on land,” said Kathryn E. Smith of the UK’s Marine Biological Association.
Major economic and human toll
The economic fallout from marine heatwaves has been profound. In Peru, the displacement of anchovies from their usual waters forced authorities to shutter commercial fisheries in 2023 and 2024, resulting in an estimated $1.4 billion loss.
In New Zealand, a marine heatwave fueled Cyclone Gabrielle in 2023, claiming 11 lives and causing over $8 billion in damages. In Libya, Storm Daniel—supercharged by warmer oceans—triggered deadly floods, killing around 6,000 people.
“The more frequently our marine ecosystems are hit by heatwaves, the harder it becomes for them to recover from each event,” Smith noted.
In response, some adaptation measures have been deployed. In Australia, part of the endangered red handfish population was moved to aquariums before being released once water temperatures stabilised. In the United States, corals and conchs were relocated to deeper, cooler marine zones. In Peru, the government provided aid to fishermen impacted by fishery closures.
Yet, these efforts remain limited and fail to address the root causes. “Ultimately, to prevent marine heatwaves and their impacts from worsening, we must reduce or halt our reliance on fossil fuels,” Smith cautioned.
A growing threat
Prior studies have shown that human-induced climate change already increased marine heatwaves by 50% between 2011 and 2021. Without intervention, these events could become 20 to 50 times more frequent and ten times more intense by the century’s end.
“The heat we’re adding to the oceans today will linger for decades. Without urgent climate action, we’re on track to lose critical coastal ecosystems—like kelp forests and coral reefs—within our lifetimes,” warned Professor Thomas Wernberg.
For scientists, the only lasting solution lies in shifting from fossil fuels to renewable energy. The fate of the oceans—and the communities that depend on them—hangs in the balance.
ARD/te/lb/as/APA