“Climate change consists of watching a series of videos of climate disasters recorded with mobile phones, closer and closer to your home, until one day you are the one who is recording.” This meme that has been circulating on the internet for a long time has gained new life after the DANA that has left dozens of dead on the Spanish Mediterranean coast.
Although we will have to wait for attribution studies to establish the degree of direct relationship climate change has with this episode, what we already know is that record ocean temperatures and the increase in moisture retained in the atmosphere are the perfect ingredients for that this happens with increasing frequency and intensity. And that the alteration of atmospheric flows produced by global warming has a determining role.
The recent torrential rains in the Sahara Desert or the unprecedented speed with which Hurricane Milton reached category 5 before hitting Florida are just two recent examples of extreme climate anomalies produced by this atmospheric situation. In the case of DANA that has hit the Spanish Mediterranean, the elements that have intervened are similar.
“There is more humidity in the atmosphere because the Mediterranean is warmer than normal,” explains Francisco J. Tapiador, professor of Earth Physics at the University of Castilla-La Mancha (UCLM). “This produces ‘strange’ circulation patterns, given that the Mediterranean climate is inherently variable.”
We are seeing very strange, very twisted wave patterns. Sometimes they are strangled and generate this type of depression at high levels like DANA.
Francisco J. Tapiador
— Professor of Earth Physics at the University of Castilla-La Mancha (UCLM).
If we open the framework, we find that what are known as jet streams are destabilized and are leading to more episodes of extreme heat and cold, and that phenomena such as the intertropical convergence zone are moving much further north than usual, which explains that the Sahara has recently been filled with small lagoons.
“We are seeing very strange, very twisted wave patterns,” says Tapiador. “Sometimes they strangle themselves and generate this type of depression at high levels like DANA.” And part of these effects are a consequence of the melting of the polar cap and the record temperatures at the poles. “What happens in the Arctic affects us because it changes the trajectory of the jet stream, and that affects the DANAS,” says the expert.
She is not ‘crazy’, but she is ‘twisted’
“It is not so much that the atmosphere is crazy“says the veteran meteorologist Angel Riveraexpert in atmospheric dynamics. “What happens to the atmosphere is that it has a more undulating circulation than a few years ago and it probably has to do with the issue of greater warming of the tropical atmosphere.” These deeper and sharper undulations cause the warm tropical-subtropical air to rise to higher latitudes through large ridges, which are what generate those tremendous heat waves that we are seeing lately, explains Rivera.
On the other hand, when there are oscillations of cold air towards the south, the contrast between that cold mass and the warm mass becomes much narrower and that makes the winds that circulate around that disturbance that is the DANA more intense. “This makes its front zone have much more intensity, much more lifting power and causes stronger storms,” he says.
The circulation of high levels and the contribution of heat and humidity from the lower layers are the perfect cocktail to provoke this type of situation.
Angel Rivera
— Meteorologist expert in atmospheric dynamics
In other words, it is atmospheric warming—produced by human activity—that gives rise to more undulating circulations, with much sharper troughs and ridges, so that these disturbed “rivers” in the sky leave more waves of cold and heat and more extreme phenomena. “If we add to that the fact that in the lower layers the air is quite warm and humid,” says Rivera, “this means that both the engine, which is the circulation of high levels of wind at altitude, and the fuel supply from gasoline from the lower layers, are the perfect cocktail to provoke this type of situation.”
Long way to go
“The jet stream or jetstream, Due to the changes we are seeing due to climate change, it is having more pronounced undulations,” agrees María José Sanz, director of the Basque Research Center on Climate Change (BC3), in statements to the SMC. The DANAS are areas of low pressure that are isolated from that jet stream, remember, and this is joined by atmospheric rivers, certain currents in the atmosphere that transport water vapor.
The tragic consequences of this event demonstrate that we have a long way to go to prepare for these types of events, and worse, in the future.
Liz Stephens
— Professor at the University of Reading.
“In general terms, many decades used to pass between events of this type, now we can find that we have them more frequently and their destructive capacity is greater,” assures Ernesto Rodríguez Camino, senior meteorologist of the State, in statements to SMC. “Climate scientists have been warning for years that climate change will lead to heavier rainfall,” concludes Liz Stephens, a professor at the University of Reading. “And the tragic consequences of this event demonstrate that we have a long way to go to prepare for these types of events, and worse, in the future.”
Finally, connecting this meteorological event with climate change is not crazy, taking into account that other previous attribution studies have shown a direct relationship between global warming and episodes such as the “derecho”, which left a dozen dead in the southern and central Europe in August 2022 or the increase in giant and potentially deadly hail storms.
For Juan Jesús González Alemánmain author of these works and expert in atmospheric dynamics at AEMET, extreme events like those he documented are those that climatologists warned us would appear if we continued with gas emissions and the increase in temperature. We will have to wait for the evidence of this new catastrophe, but so far the predictions are being fulfilled, point by point.
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