Over the past decades, global ocean warming has intensified marine heatwaves (MHWs), defined as prolonged extreme rises in ocean temperatures in specific marine regions[1] . Around the globe, both the magnitude and frequency of MHWs have increased, causing devastating impacts on marine ecosystems such as coral reef bleaching, the proliferation of invasive species and mass mortality events[2] . Additionally, MHWs increase the likelihood of extreme weather events, including cyclones. In Europe, the Mediterranean Sea has been the most affected by MHWs, experiencing a continuous increase in sea surface temperatures over the past few decades[3]. This rise in water temperatures, driven by anthropogenic activities, is expected to persist in the future. According to a report by the Intergovernmental Panel on Climate Change (IPCC), up to 90 percent of coral reefs could be lost by 2050[4].
Gaining a better understanding of MHWs is crucial for mitigating global warming impacts, protecting ecosystems and enhancing climate adaptation. This week’s map displays sea surface temperatures, recorded by drifting buoys over the past month. This global data collection effort is coordinated by the Data Buoy Cooperation Panel (DBCP). Sea surface temperature is one of the Essential Climate Variables, defined by Global Climate Observing System (GCOS), that are necessary for monitoring the global climate. Since the early 1990s, global sea surface temperatures have risen by more than 0.3 °C, and continue to increase at an unprecedented rate of 0.014 ± 0.001 °C per year, with 2023 breaking records[5].
Protecting and restoring marine ecosystems offers substantial health, social and economic benefits to coastal communities and the European Union (EU) as a whole. Accordingly, following the Biodiversity 2030 Strategy, the EU aims to protect 30% of its seas, with 10% under strict protection. Moreover, the enforcement of regulations such as the EU Nature Restoration Law seeks to restore marine habitats, providing substantial benefits, including for climate change mitigation. The EU also funds various projects aimed at reducing MHWs impacts (see below).
Wish to go further?
- Listen to the 'Into the Blue podcast' episode “Why Are We Experiencing Marine Heatwaves and How Do We Tackle Them?” where the National Oceanography Center receives Dr Jules Kajtar;
- Learn about the impacts of MHWs on the carbon cycle;
- Visualise weekly global MHWs forecasts provided by Mercator Ocean;
- Watch the latest episode of the Euronews OCEAN Series to learn more about MHWs and restoration projects;
- Discover restoration projects enhancing ecosystems resilience across Europe such as PUREEF-Y, EFFECTIVE or OCEAN CITIZEN;
- Support global coral reef restoration efforts by adopting a coral through the Coral Gardeners’ initiatives.
The data in this map are provided by EMODnet.
[1] https://www.ioc.unesco.org/en/stor2024
[2] https://academic.oup.com/oocc/article/4/1/kgae005/7666987
[3] https://marine.copernicus.eu/explainers/phenomena-threats/heatwaves
[5] https://www.noaa.gov/news/2023-was-worlds-warmest-year-on-record-by-far