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[LMD communicates] 2023 breaks all records for sea surface temperatures over Western Europe

Anomaly of ocean surface temperatures observed by the infrared sounder IASI. On the left: monthly anomaly for June 2023 (Reference for anomaly calculation: 2008-2020). On the right, time series of daily anomalies per year since 2007 for the two outlined regions, the North Atlantic at the top and the western Mediterranean at the bottom. The years 2023 and 2022 are plotted in purple and green, respectively. The black curves represent the average (thick line) over 2007-2020 and the 90th percentile (thin line).

The infrared sounder IASI independently confirms the observations of the European Centre ECMWF model via Copernicus: since 2022, the surface temperature of the North Atlantic, near the European coasts, as well as the western part of the Mediterranean, has been unusually high and regularly exceeds previously observed maxima.

In the North Atlantic, for example, the temperature in June 2023 is the highest ever recorded for this period, with an average temperature 1.5°C warmer than the norm. But the entire year 2023 is exceptional. In the western part of the Mediterranean, 2022 was a significant year, with a series of heatwaves from July to January 2023 continuing into July 2023.

These heatwaves impact the marine ecosystem and can lead to extreme weather events. They are believed to be linked to factors combining short-term effects, such as abnormally weak winds observed in June in the North Atlantic due to a weakening of the Azores high, which combine with longer-term effects such as global climate warming (see analyses from the Copernicus Climate Change Service (C3S*).

Also, see on Copernicus:

Information on the IASI SSTs used: Capelle, V., Hartmann, J., Crevoisier, C., 2022. A full physics algorithm to retrieve nighttime sea surface temperature with IASI : Toward an independent homogeneous long time-series for climate studies. Remote Sens. Environ. 269, 1–38. doi:10.1016/j.rse.2021.112838

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