Deadly Spain floods show difficulty of adapting to intense rains

Floods that killed more than 200 people in eastern Spain this week were caused by a storm that dumped a year’s worth of rainfall in less than 24 hours.

The tragedy has raised questions about whether earlier warnings could have prevented so many deaths, while the widespread damage shows how many cities aren’t adapted to withstand rainfall amplified by climate change.

Intense Mediterranean heat and rising air temperatures have worsened a type of storm increasingly common in the Iberian Peninsula due to global warming. Experts suggest that recent construction in the area has increased risk and reduced stormwater drainage efficiency.

“It may happen that the paths we have left for water aren’t large enough, and in recent decades that’s happened too many times,” said Ernest Blade, professor of river and hydrologic engineering at the Universitat Politècnica de Catalunya.

Earlier this week, southeastern Spain experienced a strong “dana” storm, a common occurrence during this time of year. Danas, (short for “depresión aislada en niveles altos”) form when cold autumn air meets warm, moist air from the Mediterranean, creating storm clouds that can produce heavy rainfall in a short time.

This year, the Mediterranean’s mean temperature reached 28.5 degrees Celsius (83.3 degrees Fahrenheit) in mid-August and has remained unusually warm, increasing the chances of intense storms. Climate change is also causing higher air temperatures, allowing storms to hold more moisture – up to a 7 per cent increase for every 1 degree Celsius rise.