Mª Carmen Llasat: “The warming of the Mediterranean points to an intensification of more intense and extensive DANAS”

15 days ago a DANA devastated Valencia and reproduced itself this week, also in Malaga and is now moving to Sicily. What is happening in the Mediterranean, what are all these episodes due to?In principle, they are part of its climatic panorama, they occur from time to time, especially in the northwest, in Spain, France and Italy, but everything points to an intensification of these episodes due to global warming and, more specifically, of the Mediterranean. . It is already more than one degree from the average, it is very hot. It is normal for it to warm up in autumn and for there to be more rain in autumn, but the increase in temperature allows for more water vapor in the atmosphere and more evaporation.

Is there any difference between the ‘old’ cold drops and the DANAS?There is a confusion. The expression ‘cold drop’ referred to almost the same thing as DANA. Both are meteorological terms that refer to a cold depression at altitude. A cold drop is a type of DANA. We can have them without there being floods and heavy rains and we can have heavy rains without there being DAMAGES. We can talk about episodes of storm intensification. This DANA, if the sea had not been so hot, it would not have given so much rain.

In addition to noting the warming of water temperatures, the report says that it does not seem to be going away, that it will continue to rise. Can these events be increased, with several occurring each year?In meteorology we never rule out that extreme events have anomalous behavior. For example, in September 1962 the floods occurred in Vallés [Barcelona] in which more than 800 people died and a month later they occurred again in the same place. Therefore, it may happen that something very rare occurs twice in a row. Now, the warming of the Mediterranean is increasing and what we are saying is that, as we have more water vapor, the temperature is higher and we have more energy, this type of situation is going to be more frequent. But more frequent does not mean that we will always have it. have occurred and the same episode is moving to other regions [Sicilia] But what does seem to be happening is that they are more intense and extensive. Anomalous phenomena because they are of intensity and the affected area has been very large, in Valencia. Last year we already had something anomalous, Hurricane Daniel that caused nearly 800 liters per square meter in Greece. [y devastó Libia]which is unthinkable. These are quantities that can be much higher because we have a source of steam that heats us up. The surface temperature of the Mediterranean has increased since 1980 and is increasing between 0.29 and 0.44 degrees per decade. That is, 0.44 per decade would be four degrees in 100 years, very high. And marine heat waves increase by more than 40%.

With these extraordinary amounts of rain that also exceeded the forecasts in Valencia, are the return periods used to calculate flood risks still valid or is it time to review the risk analyses?Yes. It is a time to review return periods to see if they can be improved. The calculation has many uncertainties because they are calculated over 500 years from observations of 50 years or less, with mathematical models, which means that they are always approximate values. It would be worth reviewing how they are calculated and seeing if now with new data we can appreciate it better.

Could this review lead to flood risk management plans becoming obsolete?It is important to take into account what has happened previously. We would have to ensure that we are capable of facing episodes that have happened in the past. Many times we work with modeling that, due to lack of data, has uncertainties and we cannot guarantee it exactly. It is very important to work with information from episodes that have already happened. There are areas that appear to have a small flood risk when we know that there have been many floods in the past.

Does it also refer to what happened in Valencia?Yes, obviously. All. Let’s review it in light of what has happened here. In other basins hardly anything has happened and it would be a proposal that all of them be reviewed in light of all the information. For example, it may happen that nothing serious has happened in a place but it did 100 years ago.

The report also speaks of the risk of flooding due to the rise in Mediterranean sea level, which also shows no signs of slowing down. In Spain, are there areas at risk of being swallowed by water or permanently flooded?In Spain, above all, the first thing that affects is the loss of beaches. The increase in erosion of the entire coast can affect the beach and the loss of sand but also infrastructure such as dikes or ports, it is a very important problem. The next problem we have in Spain is that a large part of the population and wealth associated with tourism on the coast.

Is the risk linked to urban development that you point out related to climate change?It goes together. Campsites on the seashore have been recovered, urban planning is being done on the front line [de playa]. If before it was not recommended or even prohibited, now, with this erosion and the rise in sea level, it directly affects all settlements and all activities on the coast. It would be necessary to be very restrictive with urbanization and construction on the front line. We need to give more space to the beach, which will have to grow backwards because the water will take it away from the front.

Is it to be expected that after the tragedy in Valencia the ‘chip’ regarding urbanization so close to the sea will change?It is very important and in all flood-prone areas it should be more restrictive. There have to be more restrictive political and legal decisions, but to do so it will be good to raise awareness among the population. In the Valencia disaster it has become clear that the population was consciously or unconsciously occupying flood zones and did not know what to do, regardless of the warnings and poor management. We must raise awareness, because there are many economic interests behind urban planning but it is necessary for the population to be aware of why.

The report predicts that the GDP of coastal areas will fall.It is not that sun and beach tourism will be lost, but it may be affected and may decrease. It is necessary for Spain to rethink other sources, such as the industrial sector, because, if not, we are very weak, very vulnerable. But it doesn’t mean that suddenly people can’t live. On the one hand, there is perhaps exaggerated tourist pressure and in addition to the fact that conditions in the future must be worse for tourism due to the temperature.

These days there is not much room to talk about rain and water, but the report states that climate change in the Mediterranean also results in water scarcity in coastal areas. What is the forecast for drought?It is the great concern in the Mediterranean and, within it, on the southern shore, where the models show a precipitation deficit and there is a significant increase in population and needs. [de agua]. When we talk about water scarcity we have to look at how much we have and how much we need. In the south and east [del Mediterráneo] It is where the greatest pressure is going to occur. In the north, precipitation is not distributed equally. In the south of Spain, they clearly decrease. On the other hand, in the eastern area and Catalonia it is not homogeneous, there are areas where it rains more and others where it barely rains. Water resources will mark many differences between the north and the south and east of the Mediterranean.

Are the emissions reduction commitments on the table at this time sufficient to improve the situation in the Mediterranean and avoid the consequences outlined in the report?No, they are not enough. Much stricter commitments are necessary. It has already been shown that national emissions reduction commitments [en el caso de España, un 32% en 2030 con respecto a 1990] They are well above what is necessary to reduce by 40% by mid-century. That is why a global approach is necessary, to which all Mediterranean countries sign up. The region produces 6% of the total [de emisiones] and it is necessary to raise both those who are already producing a lot and those who still have to produce. Furthermore, the Mediterranean has large sources of alternative energy, especially solar and wind in some areas.

This report is presented at COP29, where the key issue is financing for developing countries. In the Mediterranean, there is the northern shore, which has reduced emissions, and the southern shore, where they increase and, for example, are expected to suffer more from drought. To what extent is it key that these North African countries have resources to confront climate change and curb consequences that also affect, for example, Spain, as we have seen these days?It is important that this negotiation for financing goes ahead and also that it contemplates new models of economic development, they cannot repeat the mistakes of the north, such as creating an automobile industry with a car in every door, we must look for other models.