Trend Analysis and Spatial Behaviour of the Fire Weather Index in the Mediterranean Iberian Peninsula, 1971–2022

• Published in: International journal of climatology Vol. 44; no. 16; pp. 6065 - 6082
• Main Authors: Orgambides‐García, David, Corell, David, Estrela, María José, Barberà, María Jesús, Miró, Javier
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 30.12.2024; Wiley Subscription Services, Inc
• Subjects: Altitude; Anthropogenic climate changes; Anthropogenic factors; Climate and weather; Climate change; Climatology; Confidence intervals; Distance; Environmental risk; Fire weather; fire weather index; Mediterranean climate; Mediterranean Iberian Peninsula; Precipitation patterns; Seasonal variations; Spatial analysis; Statistical analysis; Temperature variations; Trend analysis; Weather; Weather index; wildfire risk; Wildfires; Iberian Peninsula
• ISSN: 0899-8418; 1097-0088
• DOI: 10.1002/joc.8684

ABSTRACT The Fire Weather Index (FWI) is a widely used metric to estimate the wildfire risk based on climatological variables. As anthropogenic climate change is expected to increase wildfire risk by affecting the climate of the Mediterranean Iberian Peninsula, we assess the expected increase in wildfire risk during the past decades. For this purpose, we employ a dataset containing daily FWI values in a 0.25° × 0.25° grid for each day of a 52‐year period, between 1971 and 2022, and perform a trend analysis at a statistically significant level. We evaluate the relation between FWI and spatial (altitude, latitude, and distance to the sea) variables to look for significant correlations. An analysis is performed at the geographic level by focusing on changes in concrete, relatively homogenous zones (subregions) to broadly study spatial patterns of change. The most relevant results are (1) the FWI shows an increasing trend across the study area (0.01 confidence level); (2) the FWI is determined by temperature variations on a multiyear scale, but annually by more volatile precipitation patterns; (3) the FWI does not uniformly behave across either space or time, and is subject to different variations in different zones; (4) summer and winter are the seasons with the most significant increase, and autumn is the only not significant season; (5) very high or extreme risks are increasingly prevalent across the territory, increasing wildfire risk and (6) the FWI more rapidly rises in areas further north, at a longer distance to the sea and at higher altitudes, with the Iberian System being the most affected region. The increase in wildfire risk requires putting in place more preventive measures. Our study results coincide with climatological trend studies on the region and bridge a knowledge gap as regards the historical climatology of the FWI. Wildfire risk derived from the climatological based Fire Weather Index has increased significantly across the Mediterranean Iberian Peninsula since the 1970′s. The FWI does not behave uniformly and grows at a faster pace in places at higher altitude and latitude, and further from the sea. Percentual change in FWI between the 2010s and the 1970s across the study region (left). The whole region experiences an increase, and greater change coincides with high‐altitude areas (right).