The Guadalmar buoy has dropped from 28.8 to 15.6 degrees in seven days, the historical minimum for the month of August. Experts are analysing the causes of this phenomenon.
The surface temperature of the sea off the coast of Málaga has experienced a historic drop in just one week. The buoy from Puertos del Estado located off Guadalmar recorded 15.6 degrees on Tuesday, August 25 at 9:00 AM, the lowest ever recorded in August since the historical series began. The previous minimum was 16.3 degrees, recorded in 2014.
The contrast is striking: just seven days earlier, on August 18, the same buoy recorded 28.8 degrees, just three tenths shy of its historical maximum. In rough terms, the water has lost 13 degrees in a week, a change that scientists describe as an unprecedented "reset" in Málaga's waters.
The decline has been irregular but continuous. According to the station's data, on Thursday it dropped to 25.3; on Friday, to 21.9; on Saturday, to 20.9; on Sunday it slightly rose to 22; and on Monday it fell again to 17.3. Just an hour after marking 15.6 degrees, the sensors were back around 16.
The phenomenon has caught the attention of experts because the usual conditions for a deep water upwelling have not occurred, which typically happens with persistent westerly or land winds. In such cases, the wind pushes the surface waters offshore and the colder, nutrient-rich waters emerge. However, the analysis of winds in Málaga city over the past week is inconclusive: although westerly and northwesterly gusts have predominated, for more than a third of the time, the wind has blown from the east or southeast.
The head of the State Meteorological Agency (Aemet) in Andalusia, Juan de Dios del Pino, has no doubts about the origin: "Not being an expert on the subject, it is clear that this large and rapid variation in sea water temperature is due to some upwelling. The sun and much less the atmosphere have the capacity for such a rapid and intense change."
Del Pino clarifies that for this cooling to have relevant meteorological effects, it should be persistent and combined with some atmospheric event such as a cut-off low or a pocket of cold air in the upper troposphere. "Nothing like that is expected in the imminent future. It may produce fog or low clouds but nothing significant," he explains.
For his part, Manuel Vargas, a physicist at the Spanish Institute of Oceanography in Málaga, points to a combination of factors: "There is no doubt that this is upwelled water. The question is whether this upwelling is local, that is, if it has occurred off the Málaga coast, or if it is influenced by what usually occurs in the Strait, with its cold waters then transported by the current." Vargas adds a third factor: the wave action, which mixes the waters and distributes the heat accumulated at the surface in a thicker layer, which would explain the surface drop.
The position of Málaga in the Alboran Sea, where Atlantic and Mediterranean currents converge, favours these abrupt changes. The current maps from Puertos del Estado showed this Tuesday the Málaga coastline "tinged" blue, while nearby waters presented yellow and orange tones, indicative of values close to 30 degrees.
This cooling provides a respite in a summer where the Mediterranean has recorded exceptionally high temperatures since May. The general marine warming facilitates the entry of tropical species and increases the risk of torrential rains in autumn. In fact, the presence of cold waters has already caused curious phenomena, such as the appearance of box jellyfish along the Málaga coastline, detected on Monday.
For bathers, the water is now noticeably colder, although the forecast is for the temperature to gradually recover in the coming days if there are no new wind changes. Experts will continue to monitor the buoy's evolution to confirm whether this is a one-off episode or the start of a trend.
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