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Climate drivers of the 2017 fires in Portugal

Background:

The year of 2017 was particularly harsh in Southern Europe: extensive and powerful wildfires took place in Portugal, Spain, southern France and Italy, linked with abnormal droughts and heatwaves. Portugal, the country with the highest density of burned area, had an extended and extraordinarily intense fire season with a record total burned area of about 500 000 hectares and more than 120 fatalities in 2017. Two particularly tragic events took place before (17–20 June) and after (15–17 October) the official fire season window established by the Portuguese authorities.

Region:

Portugal, Europe

Topic:

Fires, Wildfires, Droughts, Heatwaves

Findings:

Through a comprehensive assessment, Earth Map can identify drivers and consequences of the 2017 wildfires in Portugal looking at climatic and vegetation data.

(i) One of the main consequences of the 2017 wildfires in Portugal was the vast amount of burned areas. 520 765 ha were burned in the whole Portuguese territory in the year 2017 (Figure 1 and 3), 288 683 of them in the month of October. These numbers coincide with the ones mentioned in the paper published in Nature on the climate drivers of the 2017 devastating fires in Portugal;

(ii) Looking at the vegetation indices (Figure 2) we can observe that the burned fields overlap with the areas where vegetation indices are the lowest. This shows the direct impact that the fires had on the vegetation intensity within the burned areas;

(iii) The total annual precipitation (mm) varies considerably inter-annually and shows a downward trend (i.e. precipitation has slightly decreased since 1979, Figure 4). Precipitation was unusually low in the year 2017 (570 mm compared to average of 886 mm in the last 40 years). In terms of temperature (ECMWF, Figure 5) the graphics show a max annual temperature of more than 27°C in 2017, the highest since 1979 and an upward trend (i.e. temperature is increasing since 1979);

(iv) Finally, the Climate Water Deficit which is the difference between the potential and the actual evapotranspiration (PET-AET, Figure 6), was higher than the average in the year 2017 (1149 kg/m2 compared to average of 991 kg/m2 between 2001 and 2019).

Figure 1: Screenshot of Earth Map of the Central part of Portugal and visualization of burned areas in the year 2017 (based on MCD64A1).

Figure 2: Screenshot of Earth Map with Central part of Portugal and visualization of NDVI change in the year 2017 (MOD13A1.006). The burned areas overlap with the areas where vegetation indices are the lowest.

Figure 3: Annual and monthly burned areas from 2000 – 2019 (based on MCD64A1 v006)

Figure 4: Annual precipitation from 1979-2019 (based on ERA5 Monthly aggregates - Latest climate reanalysis produced by ECMWF / Copernicus Climate Change Service)

Figure 5: Annual (1979- 2019) and monthly (2000-2019) temperature (based on ERA5 Monthly aggregates - Latest climate reanalysis produced by ECMWF / Copernicus Climate Change Service).

Figure 6: Annual Climate Water Deficit (based on MOD16A2 v006). The Climate Water Deficit is the difference between the potential and the actual evapotranspiration (PET-AET).