2023-09-19 10:11:55
Investigacin en ‘Nature Climate Change’
Updated Tuesday, September 19, 2023 – 10:11
A study shows that the greatest impacts do not occur on the sea surface, but at depths of between 50 and 200 meters. During the summer of 2023, the warmest globally since 1880, records have also been broken in the temperature of the oceans
Jellyfish in NorwayOLIVIER MORINAFP
The summer of 2023 will go down in climatic history as the hottest globally since 1880, when global temperature records began to be taken, exceeding the average between 1851 and 1980 by 1.2 degrees, according to an analysis carried out by the Goddard Institute. of NASA’s meteorological summer (which runs from June to August). In Spain, it has been the third hottest in the Aemet historical series, behind 2022 and 2003, with four heat waves.
During this season the Earth’s oceans have also broken their global temperature record, and marine heat waves have affected places very distant from the Earth. According to the European Copernicus service, marine heat waves occurred in the summer of 2023 in several areas of Europe, such as Ireland and the United Kingdom in June, and throughout the Mediterranean in July and August. Global average sea surface temperatures continued to rise in August, following a long period of unusually high temperatures since April 2023.
The effects of marine heat waves and future projections of their impact have been studied mainly on the surface of the sea, but new research that has addressed the consequences they cause at greater depths has revealed something that has alerted scientists. due to the implications it could have on biodiversity: The effects of marine heat waves are not more intense and lasting at the surface but at greater depths.
This is stated by a team of researchers in a study published this Monday in the journal Nature Climate Change, in which they warn that the living beings that inhabit these areas could suffer the cumulative effects derived from exposure to heat waves, which they go from mass mortalities of organisms -especially among those who cannot move- to migrations of species in search of waters with more favorable conditions, which in addition to altering ecosystems, has consequences on fishing catches.
Specifically, this team led by Eliza Fragkopoulou, from the University of Algarve (Portugal)analyzed the effects of marine heat waves at depths of up to 2,000 meters using data on these phenomena collected between 1993 and 2019. Their conclusion is that the greatest effects did not occur on the sea surface, but in the area between 50 and 200 meters deep. And in addition, they lasted up to twice as long compared to the surface, which had an impact on the marine fauna that inhabits that area.
Ángel Borja, principal researcher in the area of Environmental Management of Seas and Coasts at the AZTI scientific and technological center, recalls in statements to Science Media Centre Spain (SMC), which until now had not been shown that the intensity was greater in the subsurface areas than on the surface: “It is something that has a very relevant importance and implication, since The highest biomass of organisms (invertebrates and fish) in the ocean occurs in the area we call mesopelgic, between 200 and 1,000 meters deep. This area is where what some have called the largest daily migration of animals on the planet takes place, since every night they approach the surface and then descend again,” explains the also editor-in-chief of the magazine Frontiers in Ocean Sustainability. .
According to the estimate of scientists at the IPCC, the UN climate change expert group, Marine heat waves have doubled in frequency between 1982 and 2016. The authors of THIS research also recall that the forecasts of climate scientists indicate that due to climate change, the frequency of extreme meteorological phenomena such as heat waves will continue to increase, both in intensity and frequency, therefore They consider that the impact that heat will have on marine ecosystems that live at greater depths must be investigated in more detail.
As Josh Willis, a climate scientist and oceanographer at NASA’s Jet Propulsion Laboratory, explained, there are two main factors that have led to record high temperatures recorded this year: “An El Niño phenomenon developing in the Pacific “, which adds to long-term global warming that for a century has been steadily raising ocean temperatures almost everywhere.” El Nio’s greatest impact, however, is yet to come. and is expected for the first months of 2024.
In addition to the impact on marine biodiversity and, therefore, on food production, the warming of the oceans unleashes a whole series of effects since they have an important role in regulating the global climate. As more water evaporates due to high temperatures, more powerful cyclones are also formed. which in the Mediterranean translate into medicanes or DANAS, which this year are being particularly intense in the Mediterranean.
However, there has not yet been an attribution study to establish whether climate change is behind Storm Daniel, a DANA that has caused catastrophic torrential rains in the past two weeks in Libya, Greece, Turkey and Bulgaria, or the DANA that affected Spain at the beginning of September.
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