Sub-regional marine heat waves in the Mediterranean Sea

In a warming world, society is facing major climate-related challenges and impacts, such as marine heat waves (MHW) that have devastating effects on ecosystems, threaten economies and strengthen severe storms. MHWs are substantially increasing in intensity, duration and frequency worldwide and particularly in the Mediterranean Sea. This semi-enclosed and relatively small basin responds rapidly to global warming experiencing strong spatial variations that require specific consideration, in particular to better understand the drivers, mechanisms and consequences of such extreme events on the physical, biogeochemical and biological components of the oceans.

This study proposes a comprehensive characterization of MHWs in the Mediterranean at sub-regional scale from surface to sub-surface and from open to coastal waters, using remote sensing and multi-platform in situ observations. First, the long-term evolution of MHW characteristics (mean and maximum intensities, mean duration and frequency) is analysed at sub-regional scale using the satellite observations of sea surface temperature over the last four decades. Then, the propagation of sub-regional MHWs into the ocean interior and the associated modified stratification are examined through the use of vertical hydrographic profiles from profiling floats. Finally, the ocean response to extreme temperature events is also investigated in the coastal ocean complementing the satellite observations with mooring data in the near-shore waters of the Balearic Islands.

A smart platform has been implemented to monitor, visualize and share timely information on sub-regional MHWs, from event detection in real-time to long-term variations in response to climate change, to diverse stakeholders (e.g., scientific community, educators in marine science, environmental agencies and policy decision-makers). The “Sub-regional Mediterranean Marine Heat Waves” visualization tool will help to implement adaptive management, to establish adaptation strategy and to support the marine conservation and sustainable management of the oceans in a warming world.