Weeks Of Record High Marine Temperatures In Seas Off Portugal And Spain Drive Alarm Among Ocean Scientists

[hatrack]

A recent heatwave in the Mediterranean Sea has been so severe that scientists are concerned for marine life. The human-induced climate crisis is making marine heatwaves more intense and prolonged, with sea surface temperatures off the coast of Mallorca since late June frequently exceeding 30C (86F).

Portugal’s maritime authority said the southern Algarve had experienced a marine heatwave between 28 June and 9 July. Temperatures have been significantly higher than the average observed over the past 20 years – with some areas 5C above normal.

This most recent marine heatwave has been the western Mediterranean’s most extreme for this time of year. While sea surface temperatures above 30C are not that unusual later in the summer, such conditions are unprecedented in late June.

The impact on marine wildlife and ecosystems from marine heatwaves can be significant. Prolonged exposure can drain the energy from sea creatures to a point where they can no longer survive. There is also evidence that some species go into survival mode and will not reproduce.

EDIT

https://www.theguardian.com/environment/2025/jul/21/weather-tracker-mediterranean-heatwave-marine-life-spain-portugal

[OKIsItJustMe]

1. Marine Heatwave Forecasts - 26 July

https://www.mercator-ocean.eu/bulletin/marine-heatwave-forecasts-26-july/

Marine Heatwave Forecasts – 26 July
The marine heatwave bulletin provides forecasts and analysis of marine heatwave events across the globe and throughout the year. Used datasets include observations (satellite sea surface temperature maps) and numerical model analyses (assimilating satellite and in situ observations) to derive marine heatwave forecasts for a 10-day period. This week’s forecasts were produced using as a comparison the marine heatwave situation on 15/07/2025.

Key Takeaways

• Begining of a marine heatwave in the Norwegian Sea.
• Increasing extent and intensity of the marine heatwave in the eastern basin of the Mediterranean Sea.
• Decreasing marine heatwave activity along the Spanish and French coasts.
• Increasing marine heatwave intensity in Gulf of Mexico and south of Cuba.
• Increasing marine heatwave intensity in the Sea of Japan and the Sea of Okhotsk.
• Decreasing marine heatwave extent in the Bay of Bengal.

European Zone

Marine heatwave intensity categories for 26 July, 2025. European zone. Credit: Mercator Ocean International

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