Mediterranean summer: what really ignites marine heatwaves
According to a study published in Nature, it is not the heat itself that triggers marine heatwaves, but its persistence.
2' min read
2' min read
The Mediterranean in summer turns into an open-air laboratory. It is not the heat itself that triggers marine heatwaves, but its persistence.
This is according to a study published in Nature Geoscience that for the first time clearly identifies what activates Marine HeatWaves (MHW) in the Mediterranean Sea.
Areas of high pressure from Africa, in which hot, dry air tends to descend, bringing fine weather and atmospheric stability, can stay for up to five consecutive days over the Mediterranean Sea, until the winds stop and the surface waters warm up: this is how the heatwaves that are increasingly affecting the Mediterranean are born.
Without ventilation, the sea retains heat like a cauldron left on a low-flame fire, rapidly heating up until it exceeds critical thresholds.
Working as a team, oceanographers and meteorologists analysed data collected over 40 years, from 1982 to 2022, on 123 major marine heatwave events over an area of more than 100,000 square kilometres. They found that marine heatwaves in the Mediterranean are four to five times more likely to occur when they coincide with weak winds.
