European sea surface temperature

All European seas have warmed considerably since 1870 and particularly since the late 1970s, with recent years being among the warmest on record. According to climate projections, sea surface temperature in the European basins is expected to increase by 2-6℃ by 2100 under the high emissions scenario. The frequency and magnitude of marine heatwaves have increased significantly both globally and in European seas and this is projected to continue, with increasing impacts on climate and ecosystems expected.

Published: ‒ 25min read

One of the impacts of climate change is an increase in sea surface temperature (SST). This affects species’ metabolism, distribution and phenology, with many marine species and habitats being highly sensitive to changes in SST. Increases in mean SST can also lead to increases in atmospheric water vapour over the oceans, influencing entire weather systems. The EU is committed to mitigating global warming and its negative impacts, including on oceans, and adapting to climate change.

All five European seas have warmed considerably since 1870, particularly since the late 1970s. Between 1991 and 2021, SST increased by between around 0.3°C per decade in the North Atlantic and around 0.7°C per decade in the Black Sea.

Over the past century (1925-2016), the increase in SST has been accompanied by an increase in the frequency and intensity of marine heatwaves, both globally and in European seas , with an approximate doubling from 1982 to 2016 . This has had considerable ecological impacts, including promoting harmful algal blooms, with increased risks to human health, ecosystems and aquaculture . For example, recent marine heatwaves led to unprecedented levels of vibriosis infections along the Baltic Sea and North Sea coasts. Marine heatwaves can also affect climate on land, with those in the Mediterranean Sea being thought to have contributed to amplifying heatwaves and heavy precipitation events over central Europe and triggering intense extratropical cyclones.

Globally, average ocean temperatures at the surface and for different ocean depths are expected to increase further in the 21st century, between 0.9°C and 2.9°C by 2100 for the ensemble averages under SSP1-2.6 and SSP5-8.5 . The mean SST is projected to increase at a rate about 30% slower than that of mean surface air temperature. Quantitative SST projections are available for only some regional seas in Europe. For the Baltic Sea, summer SST is projected to increase by about 2°C in the southern parts and about 4°C in the northern parts during the 21st century under medium to high emission scenarios. Marine heatwaves are also projected to increase in frequency, duration, spatial extent and maximum intensity. Such changes could have widespread effects on marine species and cause the reconfiguration of marine ecosystems.

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