New Record Temperatures: The Balearic Sea Hits Maximums of 31.87ºC in 2024

Digital tools from the Balearic Coastal Observation and Forecasting System (ICTS SOCIB) have enabled monitoring of extreme changes in the Mediterranean in 2024, including unprecedented temperatures, prolonged marine heatwaves, and increases in sea level and salinity. In 2024, ICTS SOCIB recorded a record increase in the annual average temperature of the Mediterranean, exceeding the historical average recorded since 1982 by 1.55 ºC.

According to ICTS SOCIB's tools, 2024 was the warmest year in the eastern basin (22.3 ºC) and the third warmest in the western basin (20.0 ºC). Additionally, the winter of 2024 was the warmest ever recorded in the western basin (15.6 ºC). In the eastern basin, both winter (17.7 ºC) and spring (21.4 ºC) and summer (27.9 ºC) reached record seasonal temperatures. These extreme temperatures were associated with records of 205 days of marine heatwaves in the western basin and 288 days in the eastern.

In this context, Mélanie Juza, an oceanographer from SOCIB, highlights the fundamental role of SOCIB's web applications, which, based on satellite data and in situ observations, provide key information about ocean variability. "These tools allow us to detect extreme events and analyze long-term trends," she explains. They have also observed a record in the surface salinity of the eastern Mediterranean Sea (38.9 psu) and a continuous rise in sea level, with an average increase of 3.3 cm per decade since 1993. "These tools are essential for understanding the impact of climate change on the Mediterranean and its implications for ecosystems and coastal communities," adds Joaquín Tintoré, director of ICTS SOCIB.

Marine heatwaves are prolonged periods of extreme ocean temperatures. According to the widely used definition by the international community, proposed by Hobday et al. (2016), a marine heatwave is considered when the sea surface temperature is above the 90th percentile of historical data for at least five consecutive days. In 2024, marine heatwaves showed significant variations in intensity and duration in different regions. In the Alboran Sea, anomalies reached peaks of up to 7.22 ºC relative to the period 1982-2015, while in the southern Levant, the maximum duration was 303 days. In the southern Ionian, these heatwaves persisted throughout the year.

Additionally, records show a progressive increase in sea surface temperature in certain areas of the Mediterranean. In the Balearics, the sea surface temperature has increased by 0.4ºC per decade since 1982, recording in 2024 its third warmest year, with an annual regional average of 20.2ºC. The Dragonera buoy, operated by State Ports, reached a record of 31.87ºC on August 12, reflecting the extreme conditions observed in the Mediterranean. "The observations, obtained thanks to fixed moorings and drifting buoys, highlight the precision of SOCIB's monitoring tools and the importance of its collaborations with institutions like State Ports, allowing a better understanding of climate variations in the Mediterranean," emphasizes Tintoré.

The observed data confirm the impact of global warming, according to the Copernicus Global Climate Highlights 2024 report. Following the records of global ocean temperatures in 2022 (Cheng et al., 2023) and 2023 (Copernicus Global Climate Highlights 2023), 2024 has become the warmest year recorded since 1850, with a global average air temperature at the surface exceeding 1.5 ºC relative to the pre-industrial level. Additionally, in the first half of 2024, unprecedented sea surface temperatures were recorded, partly driven by the residual effects of the 2023 El Niño event (NASA, 2024).

This warming trend continues in 2025 (Copernicus, 2025): January has been the warmest January globally, with an average temperature of 13.23°C, 0.79°C above the 1991-2020 average. In the Mediterranean, the average ocean temperature recorded in January 2025 was 17.0 ºC, 1.3ºC above normal, reflecting the continuation of this thermal anomaly in the region.

The records set in 2024 for temperature, salinity, and sea level in the Mediterranean have significant implications for biodiversity, ecosystem functioning, and the services these provide to human communities. Changes such as the intensification of ocean stratification, rising temperatures, and extreme thermal events affect essential processes like the exchange of nutrients and oxygen, impacting marine habitats.

Marine heatwaves have impacted key species such as Posidonia oceanica, crucial for biodiversity and coastal protection (Guerrero-Meseguer et al., 2017; Marbà et al., 2014), and have contributed to coral bleaching, as NOAA declared in April 2024. These phenomena not only affect ecosystems but also impact key sectors of the blue economy, such as fishing and tourism, while the rise in sea level exacerbates the vulnerability of coastal communities to storms and erosion (Smith et al., 2021; Mitchell et al., 2006). Moreover, ocean warming poses risks to human health, such as the proliferation of harmful algae and infectious diseases, as well as the potential decrease in fishery resources (UNEP/MAP and Plan Bleu, 2020). These threats add to the impacts of pollution, overfishing, and urbanization, intensifying pressure on ecosystems and coastal communities.

Applications of ICTS SOCIB

• Subregional Indicators of the Mediterranean Sea
• Subregional Mediterranean Marine Heatwaves
• TIAMAT Observatory – Cabrera Archipelago