Between May and December 2022, the Marilles Foundation detected up to five marine heat waves and has warned that the could lead to “mass mortalities”.
This information is contained in the Balearic Sea Report 2022, which contains updated data on different indicators of global change such as sea level, water temperature or air temperature over the sea, nautical, human and tourist pressures, and the response given as a society to these pressures.
According to a press release, this summer the waters of Sa Dragonera reached 33.3 degrees Celsius, the highest temperature ever recorded at the area. It has also recorded the highest average surface temperature of the Balearic Sea: 29.2 degrees.
The air temperature over land, meanwhile, has shown an increase of 0.25 degrees per decade between 1979 and 2021, almost 40 percent higher than the global average; while the water surface temperature has increased at an even faster rate, 0.36 degrees per decade in 40 years.
With regard to air temperature and its relationship with sea temperature, the Balearic Sea 2022 Report uses data up to August of last year and highlights the behaviour of summer temperatures.
Last year five marine heat waves were been detected between the months of May and December.
They pointed out that this increase in temperature has “serious consequences” for marine ecosystems and can have repercussions on the economy and human living conditions.
It also affects other processes and is one of the causes of rising sea levels, which are expected to rise by between 55 and 77 centimetres by the end of the century and by between 87 and 129 centimetres by 2150, which would mean a retreat of the Balearic beaches by between seven and 50 metres.
In fact, the rise in sea level in the western Mediterranean has accelerated in recent decades, increasing by 1.32 millimetres/year over the last 136 years (with an accumulated increase of 17.9 centimetres during this period); while over the last 41 years the increase has been 2.91 millimetres/year; and over the last 28 years it has been 3.08 millimetres/year.
Marilles warns in the report that the sea is warming while tourist pressure continues to increase, in reference to the Human Pressure Indicator (HPI), which has reached records on Mallorca and Minorca with 2022 being the year with the highest number of visitors. By September 2022, the number of tourists had already exceeded 14.3 million.
Marilles also warns of the increase in nautical pressure and explains that in the last 30 years ship calls have increased by 56 per cent, although there was a 42 per cent decrease between 2019 and 2020 due to the pandemic and a 30 per cent recovery in 2021.
The report is the result of a collaborative project in which, for the last three years, all the marine research institutions of the Balearics and public and private entities have been participating.
It gathers updated information on the Balearic Sea in order to improve management efforts and detect gaps in marine research information.