Manel Grifoll: "It's random that a flood discharges more rain in one municipality than in another."

BarcelonaManel Grifoll leads the Maritime Engineering Laboratory at the Polytechnic University of Catalonia (UPC). He is an expert in oceanic processes and the formation of certain meteorological phenomena such as storms. He insists that they are not uncommon on the Catalan coast, but emphasizes that they are now much more intense. And he explains why. "We can't fight climate change; what we must do is have roadmaps and policies that allow us to adapt to them," he emphasizes.

The images of this latest storm in Terres de l'Ebre are very reminiscent of the storm a year ago in the Valencian Community. Are these episodes becoming more frequent and intense, or is it just a feeling or a coincidence?

— Danas, or what were previously called "cold drops," are common phenomena in the Mediterranean. There were floods in the Maresme region, reported in the 1960s and 1970s, and at similar times, until early autumn. What's the distinguishing feature of recent times? It's that ocean temperatures are rising compared to previous years, compared to previous decades, and these rains are now more intense. The frequency, I think, hasn't changed. What has changed is the intensity.

Because?

— Due to climate change, the Mediterranean is now warmer at the end of summer than it was ten years ago. Therefore, more energy is transferred from the ocean to the atmosphere.

How would you explain in a didactic way what a dana is and why it occurs?

— It is a combination of a cold air mass at altitude with another warm air mass at the surface or at low altitude. This warm air mass is more humid and also has a higher temperature: it weighs less and tends to move upward. This process, which we call convection, ultimately generates vertical clouds containing water vapor, and they discharge when they reach the ground.

In Catalonia, there's a perception that the same thing always happens in Terres de l'Ebre... Is that area more prone to these phenomena?

— Well, the truth is that there is a random point in the location, that is, a dana actually dumps more rain on one municipality or another. What's not random is that this happens during these times: we have two wet seasons, spring and autumn.

And what effects does all this have on the coastline and on the proven fact that the sea is increasingly gaining ground on land?

— From a beach perspective, squalls aren't the worst scenario for the coast, as they're usually local in origin. They're very different from easterly storms.

Are the easterly storms more damaging to the coast than the danish ones?

— Yes, they cause more damage. Levante storms are generated in the Gulf of Lion, and the propagation of the waves makes the Levante swell more destructive due to the orientation of the Catalan coast. It is the most destructive in terms of coastal erosion and damage to infrastructure.

In this latest storm, warnings and calls for prevention have fortunately meant that no fatalities have occurred. But how is it that we are still unable to predict the intensity or protect ourselves to avoid certain types of damage that keep recurring?

— Early warnings or early warningsAs we say, if used well and supported by the public administration, they can provide us with increasingly reliable data on the impact of these types of phenomena. It's also true that these are not easy phenomena, because they have a random element, as I mentioned before. On the coast, we talk above all about adaptation—not fighting, but adapting—to climate change. And adapting the coast means having the widest possible beach, with dunes that can absorb all the energy of these types of extreme phenomena.

And should a zero protection line also be built within the sea?

— We're not talking about building dikes or rigid structures, but rather, we're thinking about nature-based solutions, taking into account the air that piles water against the coast, waves, and the concomitance of tides to predict sea level rise.

From your laboratory, what are the main lines of research you are working on to better predict these phenomena and protect the coast?

— We approach the problem from three perspectives: the systematic and ongoing collection of oceanic or hydrodynamic data and variables, which we must do jointly with the administration; the use of increasingly sophisticated numerical models with greater spatial and temporal resolution that allow us to understand the coastal system's response to these types of events; and, thirdly, having a testing laboratory where we test potential nature-based solutions and see, for example, their wave-attenuating capacity.

This is in the sea. And on land, on the ground?

— Well, we work together with geologists, who are dedicated to researching river dynamics, for example, and in these disciplines there's still a lot of ground to cover. The human occupation of coastal areas, for example, is clearly an issue. The urbanization process that has occurred in the Mediterranean basin and in the Catalan regions has meant that rivers, which used to be able to flow slowly when it rained, now flow more vigorously when it rains.

And in the face of this new normal of much more intense phenomena, shouldn't we have been preparing for it for several years now? Climate change isn't a new concept for us now...

— We should be more resilient, yes. Establish active policies to make this coast more resilient and better able to cope with these types of extreme scenarios.

Are we late?

— You can see the glass as half full or half empty. There are indeed cases in which we have participated, together with public administrations, to implement more resilient solutions in coastal areas, and it's also true that administrations are also promoting or beginning to internalize all these plans. I believe there has been a change, but there are still many uncertainties about where climate change will take us.

In your experience, what should be the next, most urgent step?

— It's very important to develop long-term adaptation plans for coastal areas in the face of climate change. That is, the government, citizens, and also private companies and research centers must work together to agree on these plans to create a roadmap and establish policies for adapting to climate change. We can't fight it; we must adapt.