Every year worldwide some extraordinary wildfires occur, overwhelming suppression capabilities, causing substantial damages, and often resulting in fatalities. Given their increasing frequency, there is a debate about how to address these wildfires with significant social impacts, but there is no agreement upon terminology to describe them. The concept of extreme wildfire event (EWE) has emerged to bring some coherence on this kind of events. It is increasingly used, often as a synonym of other terms related to wildfires of high intensity and size, but its definition remains elusive. The goal of this paper is to go beyond drawing on distinct disciplinary perspectives to develop a holistic view of EWE as a social-ecological phenomenon. Based on literature review and using a transdisciplinary approach, this paper proposes a definition of EWE as a process and an outcome. Considering the lack of a consistent "scale of gravity" to leverage extreme wildfire events such as in natural hazards (e.g., tornados, hurricanes and earthquakes) we present a proposal of wildfire classification with seven categories based on measurable fire spread and behavior parameters and suppression difficulty. The categories 5 to 7 are labeled as EWE.

Human activity currently plays a significant role in determining the frequency, extent and intensity of landscape fires worldwide. Yet the historical and ecological relationships between humans, fire and the environment remain ill-defined if not poorly understood and an integrative approach linking the social and physical aspects of fire remains largely unexplored. We propose that human fire use is ubiquitous and evidence that historical fire patterns do not differ from non-anthropogenic fire regimes is not evidence that humans did not practice fire management. Through literature review and the presentation of two case studies from the south-eastern USA and tropical Australia, we discuss how the study of fire ecology can benefit from paying attention to the role of humans in three thematic areas: (1) human agency and decision processes; (2) knowledge and practice of landscape fire and (3) socioecological dynamics inherent in the history of social systems of production and distribution. Agency, knowledge of fire ecology and social systems of production and distribution provide analytical links between human populations and the ecological landscape. Consequently, ignitions ultimately result from human behaviours, and where fire use is practised, ignitions result from decision process concerning a combination of ecological knowledge and belief and the rationale of livelihood strategies as constrained by social and ecological parameters. The legacy of human land use further influences fuel continuity and hence fire spread.

Living with fire is a challenge for human communities because they are influenced by socio-economic, political, ecological and climatic processes at various spatial and temporal scales. Over the course of 2 days, the authors discussed how communities could live with fire challenges at local, national and transnational scales. Exploiting our diverse, international and interdisciplinary expertise, we outline generalizable properties of fire-adaptive communities in varied settings where cultural knowledge of fire is rich and diverse. At the national scale, we discussed policy and management challenges for countries that have diminishing fire knowledge, but for whom global climate change will bring new fire problems. Finally, we assessed major fire challenges that transcend national political boundaries, including the health burden of smoke plumes and the climate consequences of wildfires. It is clear that to best address the broad range of fire problems, a holistic wildfire scholarship must develop common agreement in working terms and build across disciplines. We must also communicate our understanding of fire and its importance to the media, politicians and the general public.This article is part of the themed issue 'The interaction of fire and mankind'.

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This paper provides a brief historical overview of the Global Energy and Water Cycle Experiment (GEWEX) Continental‐Scale International Project (GCIP), the basis for selecting the principal site for this experiment, the scientific objectives, and the strategic planning that has been brought to bear in preparing for the implementation of the project. It also provides a summary of the 25 papers published in this special issue, which collectively represent the launching point for research in the GEWEX's initiatives on continental‐scale hydrometeorology.