key: cord-347354-1bh6ncls
authors: Rodrigues, Marcos; Gelabert, Pere J.; Ameztegui, Aitor; Coll, Lluis; Vega-García, Cristina
title: Is COVID-19 halting wildfires in the Mediterranean? Insights for wildfire science under a pandemic context
date: 2020-10-08
journal: Sci Total Environ
DOI: 10.1016/j.scitotenv.2020.142793
sha: 
doc_id: 347354
cord_uid: 1bh6ncls

Wildfires in the Mediterranean are strongly tied to human activities. Given their particular link with humans, which act as both initiators and suppressors, wildfire hazard is highly sensitive to socioeconomic changes and patterns. Many researchers have prompted the perils of sustaining the current management policy, the so-called ‘total fire exclusion’. This policy, coupled to increasingly fire-prone weather conditions, may lead to more hazardous fires in the mid-long run. Under this framework, the irruption of the COVID-19 pandemic adds to the ongoing situation. Facing the lack of an effective treatment, the only alternative was the implementation of strict lockdown strategies. The virtual halt of the system undoubtedly affected economic and social behavior, triggering cascading effects such as the drop in winter-spring wildfire activity. In this work, we discuss the main impacts, challenges and consequences that wildfire science may experience due to the pandemic situation, and identify potential opportunities for wildfire management. We investigate the recent evolution of burned area (retrieved from the MCD64A1 v006 MODIS product) in the EU Mediterranean region (Portugal, Spain, France, Italy and Greece) to ascertain to what extent the 2020 winter-spring season was impacted by the public health response to COVID-19 (curfews and lockdowns). We accounted for weather conditions (characterized using the 6-month Standardized Precipitation Evapotranspiration Index; SPEI6) to disregard possible weather effects mediating fire activity. Our results suggest that, under similar drought-related circumstances (SPEI6 ≈ -0.7), the expected burned area in 2020 during the lockdown period in the EU (March-May) would lay somewhere within the range of 38,800 ha ± 18,379 ha. Instead, the affected area stands one order of magnitude below average (3,325 ha). This stresses the need of considering the social dimension in the analysis of current and future wildfire impacts in the Mediterranean region.

mobility allowed during a significant amount of time, at least several weeks. The strength and duration of such measures varied from one region to another, yet the European Mediterranean Region (EUMed, e.g., Portugal, Spain, France, Italy and Greece) remained under countrywide lockdowns spanning from March to May 2020 (Thomas et al., 2020) . Despite the positive epidemiological effect, the post-lockdown economic scenario is looking grim and countries are experiencing large GDP drops, which will intensify in the near future.

From an environmental perspective, the response to COVID-19 has caused noticeable impacts such as the unparalleled drop in air pollution over some of the largest metropolitan areas in the world (Saadat et al., 2020; Zambrano-Monserrate et al., 2020) . Nevertheless, the sustained cessation/reduction of human activities poses unforeseen implications over anthropogenic dominated landscapes, and has set an open and ongoing debate between those who see the pandemic as an opportunity to demonstrate environmental restoration potential options and those who advocate about potential negative impacts in the future (Chakraborty and Maity, 2020) . In the particular case of wildfires, the cessation of human activity may reduce their incidence in the very short-term, especially during the winter-spring season, known to be the most associated with human-related fire occurrence (Rodrigues et al., 2018) . However, researchers, managers and firefighters are already warning about the potential subsequent impacts on and of wildfires.

For example, the lack of activity may lead to a significant reduction in forest management -especially of interventions without immediate economic return such as fuel reduction treatments-, fuel accumulation, and limited or impaired firefighting capability (social distancing), which coupled to fire-prone conditions and budget limitations, may foster extreme wildfires (EWEs) in the mid-to-long run. Furthermore, given the increased severity of the disease in people with previous pathologies, especially respiratory ones, smoke from EWEs may boost the vulnerability to the virus (Emami et al., 2020) . So far, the pandemic raised more questions than answers, though the entire society and especially the scientific community, is working towards solving the most pressing ones. What is going to happen under a scenario of budgetary constraints and likely subsequent infection waves is yet to be seen, but surely merits further research efforts.

In this work, we present a preliminary and concise analysis of the potential impacts in wildfires of the societal and public health response to COVID-19. We analyzed wildfire activity during the lockdown J o u r n a l P r e -p r o o f Journal Pre-proof period in the EUMed countries -March to May-focusing on the progression of burned area during the most recent decades (2003) (2004) (2005) (2006) (2007) (2008) (2009) (2010) (2011) (2012) (2013) (2014) (2015) (2016) (2017) (2018) (2019) (2020) . We paid special attention to weather conditions (characterized using the 6-month Standardized Precipitation Evapotranspiration Index; SPEI6) so that we could better isolate the actual effect of curfews and lockdowns. The SPEI is a well-known indicator of water balance and drought conditions that has been previously used to predict fire activity (Marcos et al., 2015) or in the analysis of some of the most recent extreme wildfire episodes in Portugal (Turco et al., 2019) and Australia (Nolan et al., 2020) . Our main goal was to determine to what extent the response to COVID-19 has affected wildfires under the hypothesis that the cessation of human activity would prompt a drop in wildfire incidence. Within this framework, we discuss possible implications and opportunities for wildfire science.

Data on burned areas were obtained for the most fire-affected countries in the EUMed region -Portugal, Spain, Italy, France and Greece-all of them experiencing strict lockdowns and mobility restrictions. We retrieved the burned area extent during the lockdown period -March to May-on a yearly basis since 2003, using the MODIS product MCD64A1 version 6 (Giglio et al., 2018) . The MCD64A1 product provides reliable, homogeneous and up-to-date data since 2003 (Boschetti et al., 2019) , distributed in monthly raster files at 500x500 meter resolution. Values of burned area were summarized into yearly time series by country, expressing them as Z-Scores (subtracting the mean and dividing by its standard deviation) to enable direct comparisons between countries while also enabling their interaction with SPEI.

Additionally, we also characterized the thermo-pluviometric conditions using the 6 months SPEI (SPEI6) based on May (thus covering the period December-May). SPEI6 was retrieved on a yearly basis as calculated in the Global Drought Monitor (Beguería, 2017) , which provides SPEI values at 1x1 degree conditions (e.g., 2005, 2011, 2012 and 2015) , instead of the current 3,325 ha in 2020 (Table 1) . It has long been recognized that ignition probabilities are determined by human activities but most of previous scientific work has modelled ignitions from weather and geographical variables eluding the link with human-related drivers (Costafreda-Aumedes et al., 2017; Rodrigues et al., 2018) . Therefore, direct impacts of changing socio-economic activities in fire incidence remained unquantified until now (François-Nicolas et al., 2018) . 

Under strict limitations on human activities, winter-spring 2020 fires have experienced a measurable and significant decrease in all EUMed countries, becoming an outlier in fire statistics. Wildfire records for 2020 clearly separate from previous trends so far, posing a challenge for data management and interpretation in future analyses. It remains to be determined how lastly the effects of the pandemic will affect fire incidence (the 2020 summer season, longer?), but implications for future wildfire research are evident, if only to measure how fire activity would respond to cessation of human activity in the Mediterranean. In the event of upcoming waves conducive to further mobility/activity restrictions, we may experience decreased fires for an undetermined period. Quantitative assessments like ours may be conducted elsewhere, or even globally, allowing identifying disruptions in fire activity and possibly preparing for exacerbated fires in the future, since sustaining this situation in time or subsequent lockdowns may well promote fuel built-up due to decreased vegetation management. Once budget and personnel constraints due to the likely economic recession reach fire governance structures and combine with the expected increased frequency of droughts and fire weather danger (Jolly et al., 2015; Turco et al., 2017) , a perfect-storm confluence of conditions may trigger amplified wildfire disasters. On the other hand, certain COVID-related responses may exert a direct influence on firefighting capability. To the expected decline in means and resources due to budgetary constraints, specific measures like individual quarantines may add to the existing limitations in personnel.

In the same line, social distancing strategies may also hinder firefighting or prescribed burning training operations and volunteer activities (i.e. Forest Defense Associations, ADF in Spain) by impeding practices requiring close teamwork at the threat of infection.

The unpredictable mid-term consequences of COVID-19 on fire regime dynamics add uncertainty on top of an already controversial clash of current and proposed management frameworks, i.e., "fire exclusion" versus

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We thank the two anonymous reviewers for the insightful comments, which have undoubtedly contributed to improve this work.
