Sub-regional marine heat waves in the Mediterranean Sea

Abstract

<p>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.</p><p>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 <em>in situ</em> 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.</p><p>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.</p>

Connections between "Extreme Marine Events" and Biological EOVs Report

“…2b) and intensity (Fig. 2c) of MHWs in this NE Atlantic local model do not exhibit the same magnitude of change as that observed in the Mediterranean (Juza et al, 2022). This is likely related to the complex oceanography off SW Ireland (e.g.…”

“…More recently, the trends in the number, duration and intensity of MHWs across the Mediterranean Sea were examined in detail at the regional level (Juza et al, 2022; EuroSea project WP6 activities related to this report). One important conclusion of this work is that all the MHW indicators (frequency, duration, intensity) in the surface Mediterranean Sea have increased in magnitude during the last four decades.…”

“…Varying trends were observed across the different sub-regions in the Mediterranean Sea ranging from 0.06 °C to 0.13 °C per decade for the MHW mean intensity, 0.26 °C to 0.55 °C per decade for MHW maximum intensity, 1.23 days to 3.82 days per decade for the MHW duration and 1.1 to 1.8 events per decade for the MHW frequency. Increased occurrence and intensity of MHWs leads to enhanced thermal stratification, in particular in summer and autumn, whereas higher MHW indices extend towards the interior due to winddriven mixing and weakened stratification (Juza et al, 2022).…”

Observations in the Spanish Mediterranean Waters: A Review and Update of Results of 30-Year Monitoring

“…In 2022, unprecedented MHW events were observed, particularly in the western Mediterranean Sea [52]. In the present paper, we report updated trends of MHW characteristics over the period 1982-2022, including the two recent years 2021 and 2022 to the time series from [5].…”