The world’s oceans are heating up at an alarming rate, with marine heatwaves (MHWs) surging by 240% over the last two years according to a new study published in Nature Climate Change.
From 2023 to 2024 nearly 10% of the world’s oceans recorded their highest-ever sea surface temperatures (SST), reaching levels four times higher than historical averages. Scientists attribute this rapid warming to human-induced climate change, El Niño, and record-low global cloud cover.
The impact of prolonged MHWs has been devastating. The rising ocean temperatures contributed to heatwaves in the UK, North America, and Japan, as well as severe flooding in Ecuador, Libya, and Australia. These heatwaves also supercharged hurricanes, including Cyclone Gabrielle, which caused $14 billion in damages in New Zealand.
In the Indian Ocean MHWs played a key role in intensifying Cyclone Mocha (2023) and Cyclone Remal (2024). Scientists warn that by the end of the century, the Indian Ocean could face near-permanent heatwave conditions, with MHWs increasing from 20 days per year to nearly 250 days per year.
A Threat to Marine Life & Industries
Beyond weather disasters, the warming oceans are disrupting marine ecosystems:
- Coral bleaching is worsening, affecting marine tourism and biodiversity.
- Mass fish die-offs have been reported in the Gulf of Thailand and Gulf of Mexico.
- Commercial fisheries, such as Peruvian anchovies, have collapsed, causing $1.4 billion in losses.
The study highlights 43 major biological impacts of MHWs, including species migrating to new regions, increased whale and dolphin strandings, and disease outbreaks that threaten marine life.
Despite the devastating consequences, most affected regions lacked proper response plans, with no known mitigation actions taken. Scientists stress that urgent improvements in forecasting and early warning systems are needed to prepare for future marine heatwaves.
As ocean temperatures continue to rise, the world faces a stark reality: without swift climate action, marine heatwaves could become the new normal, with devastating consequences for ecosystems, economies, and communities worldwide