Every summer the same question comes back: why is so much burning now? The short answer is that fire has not changed, but the landscape and the climate it burns in have. A wildfire needs fuel, favourable conditions and an ignition. The ignition is almost always the same as ever —over 90% of fires in Spain are human in origin— but today it finds far more fuel, drier, over more months of the year, and with more people living inside it.
This page explains those four pieces, in order: heat, drought, shrub encroachment, and the wildland-urban interface.
What changed is not the count, it is the size
The number of incidents declared each year in Spain has been broadly stable for decades. What has changed is that a few fires account for almost all the area burned: ordinary years interrupted by episodes that burn a decade's worth in a fortnight. This is the area the European satellite system Copernicus/EFFIS has mapped in Spain each year.
—
hectares a year on average in the first decade
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hectares a year on average in the latest decade: —
—
of everything burned in the period fits into just two years (—)
Four changes that feed each other
None of the four explains what is happening on its own. Shrub-choked woodland in a wet year does not produce a megafire; nor does a heatwave over a farmed mosaic. The problem appears when they coincide.
1 · More heat: the season is no longer just summer
Spain has warmed faster than the global average. According to AEMET, the state meteorological agency, the climatological summer has stretched by almost five weeks since the 1980s: what used to be three months of high risk now looks more like five. And heatwaves, as well as being more frequent, arrive earlier: March, April and October now produce fire episodes that were oddities thirty years ago.
For firefighting, what matters is not the average temperature but the extreme days. A fire can be put out while its intensity stays below what crews and aircraft can absorb; above that threshold, neither more aircraft nor more crews change the outcome, and all that is left is protecting people and waiting for the fire to meet a change in weather or in landscape.
2 · Deeper drought: what never used to burn now does
Vegetation does not burn well while it holds water. What makes a drought dangerous is not only that less rain falls, but that a warmer atmosphere pulls water out of soil and plants far faster: the same rainfall goes less far than it did decades ago.
That changes the landscape on two timescales. Fine fuel —grass, leaf litter, twigs— loses its moisture in hours and responds immediately; coarse fuel and deep soils dry out over weeks or months, and they are what decides whether a fire stays on the surface or takes the whole forest. After several dry years in a row, the damp gully, the shaded slope and the valley bottom burn too: precisely the places firefighting counted on to stop the fire.
This observatory publishes a daily fire risk level based on the FWI index (Copernicus/ECMWF), which combines exactly that: temperature, humidity, wind and accumulated drought. How to read the risk level →
3 · Shrub encroachment: the land nobody works any more
This is the least visible change from the road and probably the most decisive. Seventy years ago the Spanish countryside was worked: crops up the last slope, livestock eating the shrub, firewood collected every year, and a mosaic of plots separated by field boundaries and tracks. That mosaic was, in effect, a free network of firebreaks that nobody designed.
With rural depopulation, that landscape closed up. Fields were abandoned, shrub colonised the terraces and the woodland grew dense and continuous, with no clearings or breaks. A fire that once met a patchwork of mown, grazed plots now has kilometres of unbroken fuel, and the shrub beneath the trees acts as a ladder carrying flame into the canopy.
≈ 55%
of Spain's territory is forest land —around 27 million hectares— and it keeps growing over abandoned fields. MITECO, Forestry Statistics Yearbook
≈ ⅓
is how much Spain's sheep population has fallen in the last quarter century: fewer mouths eating the shrub each spring. MAPA, livestock surveys
> 90%
of ignitions are human in origin: the problem is not a shortage of sparks, it is what they land in. MITECO
An important caveat: more woodland is not bad news in itself. Spain has more tree cover today than for much of the last century, and that is good for water, soil and biodiversity. The problem is that this woodland has grown without management and without breaks. The answer is not less forest, but structured forest: thinning, grazing, prescribed burning and a mosaic that gives the landscape back the breaks fire used to run into.
4 · Wildland-urban interface: when the forest reaches the front door
While the countryside closed up, people came back to it in a different way: second homes, scattered housing estates, warehouses and isolated houses on plots surrounded by trees. That zone where housing and forest vegetation mix is called the wildland-urban interface, and it is the point where a fire stops being a forestry matter and becomes a civil protection one.
The effect on firefighting is direct: every threatened estate ties up resources that stop working the main front. The house gets defended —as it must be— and meanwhile the fire grows where nobody is holding it. In many recent large fires, the fire did not win for lack of resources, but because those resources were busy defending houses and running evacuations.
What can actually be changed
Of the four pieces, two —heat and drought— are given, and only shift over long timescales. The other two are decisions: the state of the land and where and how we build. And they are precisely what determines whether an extreme day ends in a megafire or in one more fire.
Give the landscape its breaks back
Thinning and pruning in the densest stands, targeted grazing to keep shrub in check, bringing back crops and pasture at strategic points, and prescribed burning where the forester judges it appropriate. This is not about "cleaning up" the whole countryside —that is unworkable— but about choosing where: the places fire always passes through.
Let the house defend itself
A maintained perimeter strip, the first five metres clear of anything that burns, vents and openings protected against embers, clean gutters, and access that lets a fire engine get in and out. A prepared house can survive with nobody defending it, and that frees up resources for the front.
Plan before building
Much of the risk is decided in land-use planning, not in firefighting. Regulating where building is allowed against woodland, requiring self-protection plans and guaranteeing evacuation routes is cheaper and more effective than any aircraft.
And even so: preventing ignition still comes first
With more than 90% of ignitions human in origin, respecting restricted periods, not using spark-generating machinery on high-risk days and not burning debris out of season remains the best value measure there is. Guide to what to do before, during and after (in Spanish) →
Where the data comes from
- Area burned per year: EFFIS / Copernicus, this observatory's own series (fires of 1 ha or more grouped by municipality and day).
- Climate trends in Spain and the length of summer: AEMET.
- Forest area, fire statistics and causes: MITECO, Forestry Statistics Yearbook.
- Livestock censuses: MAPA, livestock surveys.
- Historical and current aerial photography: CNIG Digital Photo Library (American Flight survey, 1956-57) and PNOA.
The diagrams on this page are conceptual: they illustrate a mechanism, they do not represent measurements. The only measured data is the chart of area burned per year.
Observatorio Forestal aggregates and labels public information, but it is not an emergency service and does not replace official channels. In the event of a fire, always call 112 and follow the instructions of the civil protection authorities.
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Self-protection plans, perimeter strips, fuel management and post-fire assessment. We are forestry engineers based in Aragón. Reply within 24–48 h.