Tuesday October 17, 2023


In June 2023, the North Atlantic ocean experienced record-breaking ocean temperatures, resulting in several unprecedented extreme marine heatwaves. Such periods of unusual heat can be detrimental to marine life, causing mass die-offs of fish and other organisms, disrupting fisheries and spurring harmful algal blooms – but heat itself is not the only climate-linked stressor affecting marine biodiversity. 

The “three horsemen” of climate-driven biodiversity loss

Professor Stephen Widdicombe from the Plymouth Marine Laboratory grew up in a coastal town, where he learned to dive at a young age. “The sea has always been part of my life, so I naturally got into the field of marine biological science,” he says. “I became especially interested in how human activities impact marine life, in particular through climate change. By carrying out experiments, I started testing hypotheses to better understand the responses of particular species and how they were impacted by potential future climate change conditions,” he adds.

Although the connection between greenhouse gas emissions and rising global temperatures is now  widely understood in society, Prof. Widdicombe warns that heat is rarely the only stressor our planet’s marine ecosystems have to face. “Talking about rising temperatures is easy, but it is much harder to bring attention to the other ‘two horsemen’ of climate-driven biodiversity loss in the ocean, ” he says. “You can put your feet in the water and feel that it’s warmer than usual, but ocean acidification and deoxygenation aren’t such tangibly understood and obvious concepts.”

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