A new study paints a stark and precise picture of warming, acidification, and declining oxygen levels ravaging marine ecosystems. By analyzing key health indicators in different climate scenarios, researchers have created the most detailed map yet of how the oceans are changing. This information is crucial for planning and managing sustainable and effective solutions.

Climate change is affecting the physics and biology of marine ecosystems through warming, acidification, deoxygenation, and changes in productivity. Observations of global oceans suggest that these changes are happening much faster than expected and are already harming different parts of the ocean in many ways.

To study how climate change affects marine habitats, climate predictions need to account for different situations and span different scales that are useful for planning and management. Moreover, having various models and scenarios is necessary to account for uncertainties.

An international team of researchers published in Scientific Reports a comprehensive study offering detailed projections of climate change impacts on marine ecosystems in the European region. This research covers diverse mitigation pathways with unprecedented resolution, carefully incorporating underlying uncertainties. These findings are essential for informing ecosystem-based planning and the management of nature-based solutions.

To fill existing gaps, the researchers used statistical downsizing on climate models, examining five important indicators of ocean health – namely temperature, salinity, pH, oxygen, and chlorophyll – in European waters.

In the context of the EU-funded FutureMARES project, CMCC scientists played a crucial role in designing this downscaling approach, overseeing its implementation, validating datasets, and assessing uncertainty.

In particular, using a statistical downscaling of CMIP6 models, the scientists generated a high-resolution climate ensemble, comparing their projections with real observations in four European regions: North Sea, Baltic Sea, Bay of Biscay, and Mediterranean Sea.

They found out that their downsized predictions match well with the actual climatic conditions from 1993 to 2020. Results give average values of the extent of warming, acidification, and deoxygenation across all marine areas surrounding continental Europe, and estimate uncertainties, which can be used to predict the success of Nature-based Solutions, like restoring habitats such as seagrass and kelp.

“This work clearly highlights the contrasting exposures to climate change pressures and highlights the necessity of a consistent climate mitigation policy to achieve climate targets that emerge with confidence from the background variability of the system,” said CMCC scientist Momme Butenschön, an author of the study.

Although all three stressors of warming, acidification, and deoxygenation are on the rise under future conditions across European Seas, results show that the intensity of these trends and the effectiveness of various mitigation approaches differ based on the specific stressor and location.

In general, acidification exhibits the most noticeable trend, with distinct acidification levels emerging within a few years under different mitigation scenarios. Conversely, variations in warming and deoxygenation mitigation levels become apparent only in the latter half of the century, primarily due to natural variability and model uncertainty.

The varied differences in these three indicators show that detailed predictions about the physical and chemical aspects of different areas are necessary to grasp how climate change might affect marine ecosystems at a regional and local level.

We have developed high resolution climate data for coastal waters,” said Trond Kristiansen of the Farallon Institute, US, and lead author of the study, “which allows us to understand how ecosystems that provide critical benefits to people will be impacted by climate change.”

For more information:

Kristiansen, T., Butenschön, M. & Peck, M.A. Statistically downscaled CMIP6 ocean variables for European waters. Sci Rep 14, 1209 (2024). https://doi.org/10.1038/s41598-024-51160-1