HESFIRE · Drivers and projections of global fire activity and intensity under future climate and societal changes.

Drivers and projections of global fire activity and intensity under future climate and societal changes.

The human population has more than doubled in the past 50 years, expanding the scale and diversity of environmental impacts from our activities. The build-up of greenhouse gases in the atmosphere, as well as the degradation and conversion of natural lands, have major consequences for future climate, natural ecosystems, and human societies. The interactions between human and natural systems are complex, yet observational data, field experiments, and various types of models continue to elucidate key linkages between climate variability, ecosystem function, and anthropogenic activities. This knowledge is essential to anticipate potential changes under future conditions and to design adaptation or mitigation strategies that promote the sustainability of the coupled Human-Earth system. One of these interactive processes linking human activities and natural ecosystems is fire. The earth has been naturally affected by fires since terrestrial vegetation appeared on Earth, about 350-400M years ago. Fire has an important role in the functioning of ecosystems. As a disturbance agent, it promotes their regeneration, recycles the nutrients, and maintains biodiversity. Most forests would evolve towards mono-species stands of low productivity without fires, encouraging other disturbances such as widespread diseases. Human activities now exert considerable influence over global fire activity, however, through fire practices for agriculture, deforestation, and with accidental/criminal ignitions. Natural fires – mostly due to lightning – now represent less than 5% of all fires. On average, fires burn an area equivalent to the size of India every year, thus altering fire regimes can have significant impact on the Earth System. Fires are due to a combination of natural and human drivers converging towards fire-prone conditions. Significant wildfires are contingent on an ignition source, on the availability of fuel to burn, on low moisture conditions, and on un-fragmented landscapes to spread over large areas. The interaction among these drivers – including the deviation from natural fires due to human activities - is illustrated in a number of recent fire episodes. Devastating fires burned in tropical forests of the world due to the “El Niño” drought in 1997-1999, where human-ignited fires emitted an estimated 13 to 40% of the world’s annual fossil fuel emissions. In 2017, fires in Portugal resulting from poor forest management, agricultural abandonment and extreme weather conditions burned around 5% of the country and killed more than 100 people. Climate and societal scenarios suggest that ecosystems and society will be exposed to substantial changes in the coming decades, with a potential for increasing fire frequency and intensity. In this context, improving our understanding of fire drivers and how they will affect future fire regimes is a critical question to evaluate the vulnerability of ecosystems and the efficiency of fire mitigation strategies. The HESFIRE project aimed to address this need with a multidisciplinary approach to a) tackle the lack of knowledge on fire activity & intensity drivers; b) integrate this knowledge to develop a new generation of fire models with realistic performances and extensive fire assessment capabilities; and c) apply this framework to infer future fire projections and guidance for the design of fire mitigation strategies. The specific objectives and the conclusions reached over the two years of the project were as follow: 1- Tackle the critical gap in our understanding of fire intensity drivers for fire modeling. 2- Explore fire regimes under a variety of future scenarios and generate decision support for environmental policies. 3- Foster the development of inter-disciplinary approaches to better account for interactions within the Human-Earth System.

Data: CORDIS, © European Union