Global fire challenges in a warming world: Summary Note of a Global Expert Workshop on Fire and Climate Change

Catastrophic wildfires are increasingly common across the globe. However, fire plays also a necessary and useful tool for food security, preservation of cultural landscapes and associated ecosystems. Global fire activity is shaped by diverse social, economic, and natural drivers, which determine the likelihood of a landscape to burn. The effects of climate change associated to other planetary changes are transforming fire activity in ways that it will likely be dramatic, with potential consequences to nature and society in case of adaptation failure. Based on the limited available statistics, there is a growing trend in the costs of wildfires. The key to wildfire disaster risk reduction in a changing world now lies in learning to live with fire. Our analysis revealed the following key issues for landscape management and governance: (i) Climate change in combination with other environmental changes linked to population growth and unsustainable land-use practices, is contributing to extreme wildfire events that exceed existing fire management capacities; (ii) Fire is an inherent feature of the Earth system and many ecosystems, are dependent on it for their long-term survival; nevertheless, ongoing changes in global fire activity in terms of location, intensity, severity, and frequency will likely have immense costs to biodiversity, ecosystem services, human well-being and livelihoods, and national economies; (iii) Engagement with local communities, land-owners, businesses and stakeholders is crucial to restore and maintain landscapes that are biodiverse and functional, respectful of local cultures and identities, economically productive, and above all, fire-resilient; (iv) People have historically achieved sustainable co-existence with flammable ecosystems and have often used fire as a land-management tool, thereby shaping many modern and long-standing landscapes around the world. Traditional fire knowledge is thus key to adapting to local changes in fire activity; (v) Building adaptive capacity to confront fires must be based on knowledge of the natural and cultural roles of fire, how they have shaped our modern landscapes, and their importance in the long-term functioning of socio-ecological systems; (vi) Catastrophic fires are part of our future. Current scientific estimates are likely conservative, meaning that changes in fire activity might likely be worse than anticipated.Catastrophic wildfires are increasingly common across the globe. However, fire plays also a necessary and useful tool for food security, preservation of cultural landscapes and associated ecosystems. Global fire activity is shaped by diverse social, economic, and natural drivers, which determine the likelihood of a landscape to burn. The effects of climate change associated to other planetary changes are transforming fire activity in ways that it will likely be dramatic, with potential consequences to nature and society in case of adaptation failure. Based on the limited available statistics, there is a growing trend in the costs of wildfires. The key to wildfire disaster risk reduction in a changing world now lies in learning to live with fire. Our analysis revealed the following key issues for landscape management and governance: (i) Climate change in combination with other environmental changes linked to population growth and unsustainable land-use practices, is contributing to extreme wildfire events that exceed existing fire management capacities; (ii) Fire is an inherent feature of the Earth system and many ecosystems, are dependent on it for their long-term survival; nevertheless, ongoing changes in global fire activity in terms of location, intensity, severity, and frequency will likely have immense costs to biodiversity, ecosystem services, human well-being and livelihoods, and national economies; (iii) Engagement with local communities, land-owners, businesses and stakeholders is crucial to restore and maintain landscapes that are biodiverse and functional, respectful of local cultures and identities, economically productive, and above all, fire-resilient; (iv) People have historically achieved sustainable co-existence with flammable ecosystems and have often used fire as a land-management tool, thereby shaping many modern and long-standing landscapes around the world. Traditional fire knowledge is thus key to adapting to local changes in fire activity; (v) Building adaptive capacity to confront fires must be based on knowledge of the natural and cultural roles of fire, how they have shaped our modern landscapes, and their importance in the long-term functioning of socio-ecological systems; (vi) Catastrophic fires are part of our future. Current scientific estimates are likely conservative, meaning that changes in fire activity might likely be worse than anticipated

A Global Index for Mapping the Exposure of Water Resources to Wildfire

Wildfires are keystone components of natural disturbance regimes that maintain ecosystem structure and functions, such as the hydrological cycle, in many parts of the world. Consequently, critical surface freshwater resources can be exposed to post-fire effects disrupting their quantity, quality and regularity. Although well studied at the local scale, the potential extent of these effects has not been examined at the global scale. We take the first step toward a global assessment of the wildfire water risk (WWR) by presenting a spatially explicit index of exposure. Several variables related to fire activity and water availability were identified and normalized for use as exposure indicators. Additive aggregation of those indicators was then carried out according to their individual weight. The resulting index shows the greatest exposure risk in the tropical wet and dry forests. Intermediate exposure is indicated in mountain ranges and dry shrublands, whereas the lowest index scores are mostly associated with high latitudes. We believe that such an approach can provide important insights for water security by guiding global freshwater resource preservation.Keywords: wildfire hazard, global index, water security, water resources exposure, wildfire water ris

Scientists' warning on extreme wildfire risks to water supply

2020 is the year of wildfire records. California experienced its three largest fires early in its fire season. The Pantanal, the largest wetland on the planet, burned over 20% of its surface. More than 18 million hectares of forest and bushland burned during the 2019–2020 fire season in Australia, killing 33 people, destroying nearly 2500 homes, and endangering many endemic species. The direct cost of damages is being counted in dozens of billion dollars, but the indirect costs on water‐related ecosystem services and benefits could be equally expensive, with impacts lasting for decades. In Australia, the extreme precipitation (“200 mm day −1 in several location”) that interrupted the catastrophic wildfire season triggered a series of watershed effects from headwaters to areas downstream. The increased runoff and erosion from burned areas disrupted water supplies in several locations. These post‐fire watershed hazards via source water contamination, flash floods, and mudslides can represent substantial, systemic long‐term risks to drinking water production, aquatic life, and socio‐economic activity. Scenarios similar to the recent event in Australia are now predicted to unfold in the Western USA. This is a new reality that societies will have to live with as uncharted fire activity, water crises, and widespread human footprint collide all‐around of the world. Therefore, we advocate for a more proactive approach to wildfire‐watershed risk governance in an effort to advance and protect water security. We also argue that there is no easy solution to reducing this risk and that investments in both green (i.e., natural) and grey (i.e., built) infrastructure will be necessary. Further, we propose strategies to combine modern data analytics with existing tools for use by water and land managers worldwide to leverage several decades worth of data and knowledge on post‐fire hydrology

A Regional-Scale Index for Assessing the Exposure of Drinking-Water Sources to Wildfires

Recent human-interface wildfires around the world have raised concerns regarding the reliability of freshwater supply flowing from severely burned watersheds. Degraded source water quality can often be expected after severe wildfire and can pose challenges to drinking water facilities by straining treatment response capacities, increasing operating costs, and jeopardizing their ability to supply consumers. Identifying source watersheds that are dangerously exposed to post-wildfire hydrologic changes is important for protecting community drinking-water supplies from contamination risks that may lead to service disruptions. This study presents a spatial index of watershed exposure to wildfires in the province of Alberta, Canada, where growing water demands coupled with increasing fire activity threaten municipal drinking-water supplies. Using a multi-criteria analysis design, we integrated information regarding provincial forest cover, fire danger, source water volume, source-water origin (i.e., forested/un-forested), and population served. We found that (1) >2/3 of the population of the province relies on drinking-water supplies originating in forested watersheds, (2) forest cover is the most important variable controlling final exposure scores, and (3) watersheds supplying small drinking water treatment plants are particularly exposed, especially in central Alberta. The index can help regional authorities prioritize the allocation of risk management resources to mitigate adverse impacts from wildfire. The flexible design of this tool readily allows its deployment at larger national and continental scales to inform broader water security frameworks