Marine Heatwave Effects on Wildlife

Marine heatwaves - periods of anomalously warm ocean temperatures - are increasing in frequency and intensity due to climate change, causing significant welfare harm to marine wildlife.

Key Facts

Marine heatwaves have increased in frequency by 34% and duration by 17% since 1925
The 2013-2016 Pacific marine heatwave caused mass die-offs of sea lions, seabirds, and other species
Coral bleaching events caused by marine heatwaves have affected 75% of the world's reefs since 2016
Mass mortality events involving thousands of animals are documented consequences of marine heatwaves
Fish redistributions following marine heatwaves disrupt prey availability for seabirds and marine mammals

Welfare Considerations

Marine heatwaves cause acute and chronic welfare harm to marine wildlife. Acute effects include heat stress causing behavioral changes and physiological damage. Chronic effects include disruption of prey fish distributions that leave dependent species like seabirds and marine mammals without adequate food. Mass die-offs of sea lions and seabirds during the 2013-2016 Pacific blob event involved extreme suffering before death. Coral bleaching, while affecting invertebrates whose sentience is uncertain, devastates reef ecosystems that millions of fish depend on for food and shelter.

What You Can Do

Support climate action as the primary response to marine heatwave welfare harm
Donate to marine wildlife rehabilitation organizations that respond to mass mortality events
Follow marine heatwave monitoring reports from NOAA and similar agencies
Reduce your carbon footprint as a direct action benefiting marine wildlife welfare