The warmest sea ever observed. During this month of April, every day, the average temperature of the ocean and sea water has been above 21 degrees Celsius. Experts warn: it is accelerating more and more, we are facing an unexplored territory. An extremely warm spring that follows a particularly hot 2022 as well. Climate change favors that there are more and more anomalies on the surface of the sea and that they are more and more intense, especially in more fragile ecosystems, such as the Arctic, the Mediterranean, the North Atlantic or the western Pacific.
The data recorded in April mark a record sequence and unprecedented since the US National Oceanic Administration (NOAA) began the series in 1980. The last time it was reached similar temperatures were in February 2016. On that occasion it was the El Niño phenomenon, which cyclically warms the waters of the tropical Pacific. “Records should be an exception, not a phenomenon that repeats itself year after year”, explains Joaquim Garrabou, member of the CSIC at the Institute of Marine Sciences. “The acceleration of these processes, caused by climate change, takes us to an unknown scenario”, adds the researcher.
The pattern of ocean warming varies based on geographic location, ocean circulation, wind patterns, and underwater topography. This makes some areas particularly sensitive to this phenomenon. At the same time, these temperature changes have a direct impact on marine ecosystems and cause changes in the displacement of species and a massive mortality of those that are fixed to the substrate.
“The waters of the Mediterranean, as it is an enclosed sea, heat up faster and, therefore, the temperature anomalies are greater”, explains Rubén del Campo, spokesperson for the State Meterology Agency (Aemet ). The general temperature of the Mediterranean has increased 20% faster than the global average of the planet’s seas and oceans. With this increase, this sea becomes an ideal habitat for species from tropical environments. “In the coldest part of the Mediterranean, species cannot move because it is closed, and this causes a gradual extinction of the number of individuals”, explains Garrabou.
“For two decades, the temperature has been, every year, above the normal period”, remembers Del Campo. Since 1940, when Aemet began its series, the three temperature peaks have been recorded recently, in 2017, 2020 and 2022.
From Maine to Delaware, the northeast coast of the United States is also warming faster than most regions of North America, due to a change in ocean currents, says published research in Nature Climate Change. As a result, winters in the area have become milder and summers have become warmer. In the south of the continent, on the coast of Peru and Chile, the natural phenomenon of El Ni̱o Рso named because it appears at Christmas Рcauses a warming of the area. 2022 was marked by La Ni̱a, the opposite phenomenon that causes a cooling of the climate and camouflages the warming effects of climate change. In the Bering Sea, the decrease in sea ice has caused unprecedented warm temperature anomalies in the area. If the Mediterranean Sea warms 20% faster than the global average, in the Arctic this happens even four times faster. In the case of the Bering Sea, northern Europe and Siberia this process accelerates even 7 times faster, in relation to the period between 1979 and 2021 of a study published in the journal Communications Earth
The waters of the western Pacific, including those around the Philippines and Indonesia, have experienced significant temperature anomalies, conditioned by the natural phenomenon of El Niño and climate change. With temperature spikes causing marine heat waves that bleach coral reefs, vital ecosystems in the region. The World Meteorological Organization warns that there is a 55% chance that this phenomenon will repeat itself during the second half of 2023. If temperature records were broken in April 2023, the El Niño phenomenon could raise them even more during the rest of the year.
