Sea temperatures break records in Malaga this June

The average seawater temperature in June in Malaga bay has been 18.5 degrees Celsius for as long as official records have been kept (1984). This last weekend, the main port buoy recorded an alarming 25.7C. This is a constant and rising phenomenon. Always up a notch. Every year there's a new record and every time it is regarded as excessive. The city's oceanographic centre on the seafront views the phenomenon with concern, but they qualify it with the message that we must not panic because many policies can still be developed and each one of us has something to contribute.

Manuel Vargas, an expert from the centre and now based in the port of Malaga after decades in Fuengirola, compares the development of the start of the summer with that of 2017, which has been the one with the highest average values in seawater temperature (20.7C). This June will probably finish higher than that and become the highest on record for this particular month. There is still a week to go but the forecasts do not seem to suggest any respite.

At the beginning of June, temperatures were already reaching 19 degrees Celsius, so above the average of 18.5. By 10 June, the sea temperature had reached 20.7. Until the peak mentioned over the weekend. Vargas compares these temperatures with those of the Balearic Islands, in the strip that goes from Cabo de Palos (Murcia region) and the islands. Even the Alboran Sea - the name given to the section of the Mediterranean off the Andalusian coast - fares better than other latitudes due to certain determining factors such as the terral (inland) winds. Yes, contrary to what it may seem, this wind produces a 'reset' for the seawater, both in terms of nutrients and temperature.

The Balearic Islands are a special case in point. According to records obtained by the state ports buoy network, at the buoy on the islet of Dragonera (Balearic Islands), the sea temperature rose to a new record high of 31.87C. This was on 12 August last year. Two years ago the same record had been reached.

Every summer, the Spanish institute of oceanography, itself part of Spain's national scientific research council (CSIC), undertakes a boat-based campaign to measure parameters along the entire Mediterranean coastline. These values, together with those of the buoys, satellites and other measuring instruments such as the Argo project's profilers, feed into the big data collection on the state of marine health, including forecasts. All records are processed and made available through the European Union's Copernicus programme. The overall objective is to provide accurate, reliable and continuous information on the environment - not just the sea.

In Malaga, there is also an underwater observatory located off Baños del Carmen, the Mareto, equipped with all kinds of sensors and cameras connected to the oceanographic centre. However, in its first year of operation it has been experiencing frequent failures. Still, it is one more weapon in this arsenal for measuring everything and drawing conclusions.

Vargas explains the use of the profilers from the international Argo programme, which was launched in 1999. These are devices that are launched into the sea and sink to a depth of about 1,000 metres because there are no strong currents at that depth. Each day they descend to 2,000 metres and begin their ascent, measuring fluorescence (chlorophyll), salinity, pH, temperature and more.

It cannot be said, therefore, that when we talk about marine heatwaves like those affecting the Malaga coast, it is something lacking in consistency. The historical average for July is 20.3 degrees Celsius in the Costa del Sol province. This is lower than what is now being measured a month earlier.

We are, therefore, facing a month of June with peak temperatures around seven degrees above average. In addition, this time the land and marine climates do go hand in hand. Vargas explains that the predominance of southeasterly winds contributes to warming of the sea surface. The water accumulates along the coast and warms up.

The highest sea temperature recorded in Malaga's history was logged last summer, 27 degrees Celsius in August. "It's outrageous. These are records typical of the Balearics. But in 2023, 26 degrees was already a milestone in the province. For some time now, every time there's a heatwave, we break a record", says Vargas.

The highest temperatures logically occur in August. Then, the average is 21.5C. "In the past, we used to reach 24 degrees. And then it would drop with the terral to 17 or 18 degrees. If we continue using the historical records as our reference, the last few years are out of range," he says.

Vargas points out that the global phenomenon of climate change and the warming of the seas is affecting the recurrence of phenomena such as powerful storms that bring floods. You don't have to go far to witness this after an eventful hydrological year in the Mediterranean basins. It may also have an impact on the 'tropicalisation' of marine species. However, on this point, the marine expert believes that not everything is attributable to global warming. Maritime traffic has significantly increased: "We are increasingly finding species native to other places, such as the Red Sea. Could climate change have something to do with it? No doubt about it. But in the end there are other factors. These species didn't just fly in. Humans opened the Suez Canal and then widened it. There are the ballast tanks on ships. When empty they carry water due to buoyancy. They are usually treated to be aseptic, but the reality is what it is. And species are transported from one end of the world to the other. And from there on, the adaptation they may have is important."

That is despite the fact that the terral wind in Malaga enhances the value of a phenomenon known as 'upwelling'. Frequently occurring westerly winds push coastal waters further out to sea and, in turn, cause deep waters to circulate towards the surface. The result is that waters that may be around 16 degrees Celsius then cool the shallower waters, which can reach up to 27C on a record high day. "Our waters are rich in nutrients. Naturally, the terral 'fertilises' the sea. The organic matter that decomposes is of no use to us at the bottom because theres no light there, but this rising of the deep waters achieves this beneficial effect," explains Vargas Yáñez, who is also a founding member of the Mediterranean climate change group.

Malaga's proximity to the Strait of Gibraltar also plays a role and partially mitigates the seawater temperature.

Vargas points out that, from the border with Cadiz province to the Calaburras area, there are certain dynamics occurring with the currents there that further protect these waters from overheating. Chlorophyll concentrations in this area are extremely high, reaching 4.5 milligrams per cubic metre. This substrate favours the proliferation of marine life.