What are the long-term effects of marine heatwaves?

The latest data on sea surface temperature has made a big splash in the news, as the Copernicus Climate Change Service reported that the figures have reached new, record highs already this January. So what impact are these rising sea temperatures having on marine life below the waves? We explore this question in this episode of Climate Now.

Before we get into this, a quick reminder of the latest Copernicus data, which reveals that we had the warmest January on record, with global temperatures 0.7 degrees Celsius above the 1991-2020 average. We have also experienced the warmest 12 months in succession on record, with an average temperature over 1.5 Celsius above the pre-industrial level for the first time. This symbolic threshold is a key target of the UN's Paris climate agreement.

There was considerable variability in Europe's weather in January, however. Parts of Scandinavia experienced their coldest temperatures in decades, while in Spain there were highs at the end of the month over 8 degrees above average.

In the oceans between 60 degrees north and 60 degrees south - the seas between the two polar zones - the average sea surface temperature worldwide averaged 20.97 degrees Celsius. This is a surprising figure on a par with the absolute highest ever average of 20.98 degrees Celsius, recorded in August 2023.

Such sea surface temperatures do not augur well for the summer of 2024, raising questions about how resilient certain important ecosystems like corals can be in the face of repeated pressure from periods of warmer water.

With that in mind, the Climate Now team set off for Marseille to go diving with the researchers from NGO Septentrion Environnement. When we joined them, they were putting their gear on and heading out