An invisible inferno
In the Tablas de Daimiel National Park, a fire has been burning, but not in a way you might expect. There are no towering flames or billowing black smoke. Instead, since a severe drought in 2009, the earth itself has been smoldering. This is a peat fire, a slow, flameless combustion deep within the soil, consuming organic matter that has accumulated over thousands of years.
The cause is a combination of environmental change and human activity. The park, a UNESCO Biosphere Reserve, historically relied on the natural flooding of the Guadiana and Gigüela rivers and discharge from a massive underlying aquifer to keep its peat soils saturated. Decades of extensive groundwater extraction for agriculture—through thousands of legal and illegal wells—dramatically lowered the water table. The once-sodden peat dried out, shrank, and cracked. When the 2009 drought hit, the dried, oxygenated peat became fuel, and in some areas, it began to spontaneously combust.
This type of fire is notoriously difficult to fight. It moves slowly, like a lit cigar, consuming the carbon-rich soil from below. From the surface, the only signs may be a faint smell of smoke, wisps of vapor escaping from fissures in the ground, and areas of ground subsidence where the underlying peat has turned to ash.
A slow-motion carbon release
Smoldering peat fires are among the largest fires on Earth in terms of fuel consumed and can release 100 times more carbon than a flaming forest fire over the same area. The fire at Daimiel is releasing carbon that was sequestered and stored for millennia. This smoldering combustion is inefficient, producing large amounts of smoke containing carbon dioxide, methane, and other greenhouse gases that linger close to the ground.
The ecological damage is immense. The combustion of the peat destroys the very foundation of the wetland, altering the soil structure and reducing its ability to hold water in the future. When the fire was at its peak, less than 1% of the park's surface remained wet.
The primary method to combat the fire was a massive engineering effort: re-flooding the parched landscape. Millions of cubic meters of water were diverted from the Tajo-Segura water transfer system to drench the smoldering earth. This emergency measure, combined with subsequent wetter years, submerged the burning peat and cut off its oxygen supply, eventually controlling the fire. While the immediate threat has subsided, the wetland remains in a critical state, its long-term survival dependent on restoring the natural water balance that was lost.