Climate change is drastically reducing the flow of rivers into the sea, with potentially devastating consequences for marine life, fisheries, and the coastal communities that depend on them.
Across Europe, water stress has become a pressing issue, but its effects are hitting the Mediterranean region especially hard. Today, around 20% of Europe’s land and 30% of its population are already affected by water scarcity – and the numbers are rising.
What’s behind the drop in freshwater flowing into the Mediterranean? It’s a mix of climate change, overuse of natural resources, and growing demand for water. But projections paint an even more alarming picture.
If global temperatures rise by 4°C compared to pre-industrial levels – a worst-case climate scenario – the flow of rivers into the Mediterranean could drop by as much as 41%. This would severely disrupt the delicate balance of coastal ecosystems and have far-reaching economic and social impacts.
Italy’s Po River – the longest river in the country and a key freshwater source for the Mediterranean – has already shown clear signs of distress. Between 2001 and 2023, its water volume dropped by nearly half at least five times.
Basically, in 2022, the river really hit a low, with its flow dropping to just 39% of what’s normal. And it’s not just this river; others in Southern Europe are having the same issue, pointing to a big water problem across the whole area.
When rivers bring less freshwater to the sea, they also deliver fewer nutrients – the essential building blocks of marine life. This can reduce primary productivity, the process by which tiny organisms like phytoplankton produce biomass through photosynthesis. A drop of just 10% in this productivity can ripple throughout the entire marine food chain.
Less phytoplankton means less zooplankton, which messes with the food chain for fish, seabirds, and bigger sea animals. Experts think we’ll see about a 6% drop in fish overall in the Mediterranean. But watch out, some spots like the Adriatic and Aegean Seas could get hit much harder, maybe even a 35% dip.
The Adriatic and Aegean are two of the Mediterranean’s most heavily fished areas. A sharp decline in fish populations would hit coastal communities hard – especially those that rely on fishing for income and food security.
But that’s not the only danger. Freshwater also affects the salinity and temperature of coastal waters – key factors for fish reproduction. Some marine species may adapt to changing conditions, but commercially important fish like bluefin tuna and mackerel could struggle to survive in altered environments.
The economic impact of shrinking fish stocks could be enormous. Losses in the fisheries sector could reach €4.7 billion per year. In some regions, like the Adriatic and Aegean, the losses might exceed the current value of annual catches, putting the entire fishing industry at risk of collapse.
And it doesn’t stop there. Tourism – a major economic driver in the Mediterranean – could also suffer if marine ecosystems degrade. The loss of biodiversity and natural beauty would make the region less attractive to visitors, threatening thousands of jobs in tourism and hospitality.
Recognising the growing danger, the European Union is taking action. One major initiative in the works is the Water Resilience Strategy, which the European Commission is preparing for 2025.
The EU is trying to fix the Mediterranean’s water problems with a new strategy to manage water better, stop floods, and deal with droughts. But it’ll only work if all the countries in the EU team up and actually do what the plan says.
So, to fix the Mediterranean water problem, the experts think we need to look at the whole water picture, like rivers, lakes, and the sea, all connected.
EU laws like the Urban Wastewater Treatment Directive and the Water Framework Directive highlight the importance of protecting freshwater ecosystems. Still, there’s a clear gap in protecting marine environments from the impacts of freshwater shortages.
Current EU laws emphasise protecting freshwater ecosystems, but there’s still a noticeable lack of focus on shielding marine environments from the consequences of freshwater scarcity.
Because this isn’t just about fish or summer holidays – it’s about the future of millions of people, entire ecosystems, and the climate resilience of our continent.
Whether you live by the sea or hundreds of kilometers away, what happens in the Mediterranean affects us all. Understanding the crisis is the first step. Acting on it – together – is the next.
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