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Giovedì 20 gennaio 2022 - 17:45

Ocean temperatures at a record high, also in the Mediterranean

Year 2022 sounds a climate change alarm

Ocean temperatures at a record high, also in the Mediterranean
Roma, 20 gen. (askanews) – According to a study published in the journal Advances in Atmospheric Sciences, ocean temperatures set a new record in 2021, continuing their record-breaking temperature streak for the sixth straight year, and the Mediterranean is an hot spot of the global crisis, warming up faster than the rest of the planet. The article Another record: Ocean warming continues through 2021 Despite La Niña Conditions, authored by an international team of 23 researchers from 14 institutions (including Simona Simoncelli at INGV, the National Institute of Geophysics and Volcanology and Franco Reseghetti at ENEA, the National Agency for New Technologies, Energy and Sustainable Economic Development) was written using dataset available as of December 31, 2021 and also reprocessing earlier data, based on new knowledge acquired in the meantime.

The researchers highlight that the oceans in 2021 absorbed heat equivalent to 7 atomic bombs detonating each second, 24 hours a day, 365 days a year.

And the new record, they said, was hit despite La Niña, a phenomenon which helped cooling the Pacific Ocean in 2021.

For the Mediterranean, the alarming results shown in the study are accompanied by those of temperature monitoring in the Ligurian and Tyrrhenian seas, resumed in 2021, as part of the project INGV MACMAP, in which ENEA participates. Since 1999, using commercial ships that ply the route between Genoa and Palermo, temperature data has been acquired which has allowed the analysis of thermal variations over time. Key partner of this activity is the Italian shipping company GNV S.p.A. (Grandi Navi Veloci) which launch the probes that measure temperatures.

“It is very important to emphasize that the ocean absorbs a third of humanity’s carbon dioxide emissions however, ocean warming reduces the efficiency of oceanic carbon uptake and leaves more carbon dioxide in the air. Monitoring and understanding how the thermal and CO2-related components evolve in ocean waters, both individually and in synergy, is very important to arrive at a mitigation plan that respects the approved objectives to limit the effects of climate change” pointed out Simona Simoncelli at INGV.

“For example, ocean warming leads to (omitting the contribution of melt water from the glaciers), a higher volume and sea level, resulting in negative consequences for the Pacific atolls and island states such as the Maldives as well as for our coastal areas – continued Simoncelli -. As oceans warm, the water expands and sea level rises. Warmer oceans also supercharge weather systems, creating more powerful storms and hurricanes, combined with periods of extreme heat in increasingly extended areas. And this without considering the biological effects: warm water holds less oxygen and this alters the food chain, just like acidic water affects living organisms. ”

“During the last data collection campaign, in mid-December 2021, I was first baffled and then increasingly discouraged by what appeared on the acquisition system monitor – Franco Reseghetti at ENEA, said -. In the Tyrrhenian Sea I found the isotherm T = 14 ° C almost always below 700 m, sometimes even around 800 m, depth values that surprised me. Basically, a deeper area has begun to heat up than in the past. I analysed these December data deeply with Simona Simoncelli, also looking for confirmation in datasets obtained from other measuring instruments in the same area and in the same period. But unfortunately our results showed good agreement with the others and confirmed a new record high (although if we would have gladly done without it). ”

“This hot water began to enter the Tyrrhenian Sea from the south, starting from the Egadi islands and the north-west coast of Sicily, and continued northwards, affecting an ever wider area and at increasing depths. Unfortunately – continued Reseghetti – we cannot make predictions for 2022, even if the path taken in recent years by the Mediterranean Sea seems clear, with ever increasing water energy values which interact with the atmosphere causing increasing extreme weather events like heat waves and violent rain storms previously unknown in these regions. The year 2021’s weather events were proof of this: the heat in Sicily in August, the rain in Liguria, the ‘medicanes’, the Mediterranean hurricanes at the end of November again in Sicily, just to give an example”.

More specifically, the time series of temperatures in the Mediterranean show more significant increases than those observed at the same intermediate depths in other areas of the global ocean.

“Since spring 2013, we have seen a progressive warming of the layer between 150 and 450 m depth (but temperatures are increasing even at greater depths), with an even more evident growth between 2014 and 2017, followed by a slight decline in 2018-2019 and a further rise in 2021” pointed out Simona Simoncelli. “For the Tyrrhenian and Ligurian seas, in the period 1999-2021 the temperature variation was equal to 0.028 ° C / year, consistent with what recorded in the Sicilian Channel by the CNR instrumentation which has acquired data since 1993. Their estimated increase in temperature is 0.026 ° C / year over the whole period, but with a growth of 0.034 ° C / year after 2011. The average temperature variation in the 150-450 m layer is about 0.6 ° C (from 13.8 ° C to 14.4 ° C) “.

“This further warming, which can be seen as an indicator of the persistence of climate change, arrived, ironically, at the end of the first year of the” Decade of the Sea “(https://decenniodelmare.it/), the initiative launched by the United Nations to mobilize government and civil society and making fundamental changes in the way we study and manage the ocean, to sustainably conserve and use ocean resources” Simoncelli and Reseghetti said.

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