Last year, sea surface temperatures in the North Atlantic and globally were already at record levels. There can be no talk of a trend reversal or stabilization, on the contrary. In this respect, 2024 is once again in a league of its own!
North Atlantic too warm
A year ago at this time, the average sea surface temperature was well above average, but not yet at record levels. However, this changed at the beginning of March, and from then on it exceeded all years since satellite observations began in 1981. The anomaly gradually intensified over the course of the year, and in August and September it exceeded 25 degrees – for many weeks, which was unprecedented at the time. In the fall and winter, the water temperature always remained at record levels, and has done so again this year. The degree of the anomaly is absolutely unique and the gap to previous years is enormous. The annual low will be reached in the next one to two weeks, after which the trend will point upwards again.
Fig. 1: Average sea surface temperature in the North Atlantic compared with the years since 1981; Source: climatereanalyzer
Fig. 2: Sea surface temperature anomaly in the North Atlantic; Source: climatereanalyzer
Global water temperatures also high
The situation is no different on a global level either. In January and February 2023, La Niña prevailed in the equatorial Pacific and still had a dampening effect. After the ENSO swing tipped over the neutral state towards El Niño, we entered uncharted territory, with the average sea surface temperature between 60° North and 60° South far exceeding all other years since 1981. In fact, we can speak of absolute uncharted territory, that's how big the gap is. For several weeks, the value was over 21 degrees. This value had only been reached once before (in 2016). This year, with the exception of a few days, we were always above 21 degrees.
Fig. 3: Average sea surface temperature in the North Atlantic compared with the years since 1981; Source: climatereanalyzer
Fig. 4: Global sea surface temperature anomaly; Source: climatereanalyzer
Water has a very high heat capacity and can store a lot of energy. The warm water releases this energy to the atmosphere above it, increasing evaporation rates. A warmer atmosphere can absorb more water vapor, which in turn leads to more precipitable water. El Niño still prevails in the Pacific (see Figure 4, the tongue of warm water in the equatorial Pacific), but according to current forecasts it is already coming to an end. During the second half of the year, La Niña is very likely to reappear. It will be interesting to see how great the dampening effect on the current record-high sea surface temperatures will be.
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