Exploring natural disasters with Earth Map: Sierra Bermeja, a ‘sixth generation wildfire’ in Spain
In this article we present Earth Map, a free and open-source software developed by the Food and Agriculture Organization of the United Nations (FAO) to facilitate the visualization, processing and analysis of land and climate data. Earth Map has been developed in the framework of the FAO-Google partnership thanks to the support of the International Climate Initiative (IKI). Earth Map is also one of the free open-source solutions for environmental monitoring under the umbrella of the Open Foris Initiative. Using Earth Map we will explore the recent Sierra Bermeja wildfire and present our findings.
The ‘sixth generation wildfire’ and its consequences
Experts claim that the Sierra Bermeja wildfire has been a landmark event due to its nature, being one of the first “sixth generation wildfires” in Spain capable of creating its own meteorology in the form of fire clouds. There are three key elements that will help understand the nature of the event: (i) rural abandonment and unsustainable land use management, (ii) changing fire regimes, and (iii) weather conditions that promote wildfires. These events have become more probable in southern Europe, northern Eurasia, the USA, and Australia over the last century. The consequences are many, local news reports that the fire lasted almost a week, burning over 10,000 ha, taking the life of one firefighter and leading to the displacement of over 3 000 people.
The landscape in southern Spain is famous for tree species such as Abies pinsapo, that only grows in three enclaves in the world scattered throughout the mountains of Andalusia, in Cádiz and Málaga. To better understand the context in the province of Málaga, we investigate data on past fires with MODIS global datasets (spatial resolution: 500 m) available in Earth Map. Annual statistics on fires show that only small areas have been subjected to fires in the last 20 years with only one exception: in 2012 an unusually strong fire located in the western part of Costa del Sol ravaged 9,940 ha of forest, cropland and grassland. In addition, we can find fire-prone months by assessing monthly statistics, which normally coincide with the hottest months of the year (July, August and September). All these statistics and more can be generated with Earth Map in a matter of seconds.
Furthermore, the images presented below can be easily visualized, shared and downloaded with the Imagery Compare Tool, a Google Earth Engine App embedded in Earth Map which allows rapid access to multiple Earth Observation sources (Sentinel, Landsat, MODIS) to monitor areas in real-time, especially useful to monitor extreme events or climatic disasters.
The combination of satellite images and maps presented above helps the Earth Map users to better understand the nature of the event, the extension of the scorched area, the burn severity and the burn ratio patterns in the area. For this purpose, we present images in different time frames before (5th September 2021), during (10th September) and after this violent wildfire (18th September). We showcase two different Sentinel 2 datasets; (i) a false color composite with the near infrared, red and green bands widely used to assess plant density and health, (ii) a derived Burn Severity (dNBR) map that illustrates the difference between the pre-fire and post-fire vegetation status, which then can be used to estimate the burn severity.
In this example, using the date selection boxes, the user will be able to find the less damaged zones of the wildfire, having a closer look at the image from the 18th of September . Located on the middle-lower left area the user will see that a spot remained unburned or with low severity damage coinciding with the location of the Pinsapar forest.
One of the most useful features of this tool is the area measurement function available in the Imagery Compare. Users can roughly estimate the burned area of this extreme fire event (around 9900 ha) by delineating the burned surface by hand. The polygon can then be downloaded as a KML ( example of delimited area for Sierra Bermeja ) and used in Earth Map to analyze the land cover of the burned area according to CORINE, ESRI 2020, MODIS, GlobCover 2009, Copernicus Prova-B or CCI LC datasets.
Reports from scientists and local conservation organizations claim that the renowned Pinsapar in Sierra Bermeja has been surrounded by fire and some of the specimens have suffered serious damage (10%), but that luckily the fire has not reached the closed Pinsapo forest located in the natural area of the Reales de Sierra Bermeja (which can be easily spotted thanks to the Sentinel-2 imagery). Moreover, the regeneration of the area can be monitored over time as the images and datasets accessible through Earth Map are always up-to-date.
Aspect and elevation for identification of species distribution
Earth Map’s geophysical section can complement the information gathered on the fires. There are a few datasets available derived from the USGS Shuttle Radar Topography Mission such as the elevation and the aspect that will help to better assess the local circumstances and in this case to better understand the location of the endangered species Abies Pinsapo.
The Spanish Fir or Abies Pinsapo habitat is characterized as a pure forest or mixed forest with oaks, mainly located on peaks and slopes exposed to the north or north-west between 1000–2000m altitudes. This information can be found in the Earth Map tool and displayed as a series of maps with elevation and aspect related information.
Rapid assessment of climate and vegetation variables
Climatic factors, accessible through Earth Map, can explain the origins and evolution of the fire. The image below illustrates the spatial distribution of precipitation anomalies in southern Spain. It indicates a decreasing trend in precipitation in the province of Málaga and the western regions of Andalusia, that could contribute to drought- similar conditions. At the same time the average Normalized Difference Vegetation Index (NDVI) shows the patterns in density of green vegetation. The Sierra Bermeja mountain range is often described by local botanists as the lungs of occidental Costa del Sol due to its microclimate, oxygen production, carbon storage capacity, soil and flood protection functions and landscape with native fauna and flora, thus it presents higher NDVI values their surroundings in comparison. This landscape with the category of protected area needs to be better managed and decision makers should work on action plans to avoid the development of these historical wildfires that come with catastrophic consequences.
The Earth Map development team invites local decision makers, researchers but also members of the general public to explore this innovative tool that enables anyone to conduct robust land and climate assessment of any area of the world without the need of being a GIS or Remote Sensing expert. Thanks to Google Earth Engine, the cloud-computing service which powers Earth Map, users have the possibility of undertaking on-the-fly comparison of satellite images from different sensors and timeframes and statistical aggregations executed on any device in a matter of seconds, regardless of the device’s computational power.
For users who wish to learn more about Earth Map or use the software for a land and climate assessment, the following supplementary materials are available: Earth Map Help Center (https://help.earthmap.org/). The code for the Imagery Compare GEE App can be accessed from this link ( requires Google Earth Engine developer access).
For more information on fire events or the wildfire in Sierra Bermeja, you can access other freely available software for fire detection, forecast and analysis such as the European Forest Fire Information System (EFFIS) that offers forecast possibilities thanks to indices such as the Fire Danger Index (FDI) or the Sentinel Hub with global coverage and access to imagery at any scale.
The authors of this article are Carmen Morales, Laura Guarnieri, Alfonso Sánchez-Paus Díaz, Danae Maniatis and Giulio Marchi who all work at the Food and Agriculture Organization of the United Nations (FAO).
