Orals

Vegetation fires are an ancient, powerful, and pervasive biogeophysical process that affects the Earth System through complex interactions and feedbacks. The evolution and geographic spread of fire-wielding hominins in the Pleistocene has led to drastic, and ongoing, changes to the Earth System, a syndrome captured by the Anthropocene concept. Contemporary fire regimes are increasingly causing detrimental social, environmental and economic impacts, driven by the interaction between climate change and inappropriate land management practices. Achieving global environmental sustainability demands rethinking the relationship of humans, landscapes and fire. This requires careful blending of transdisciplinary thinking, translational research practices, and incorporation of indigenous and local knowledge. 

How to cite: Bowman, D.: Adaptive thinking and the global fire crisis , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20957, https://doi.org/10.5194/egusphere-egu2020-20957, 2020.

Landscape fires interact with human health in a diversity of ways, both positive and negative, and can influence many basic human needs including promoting or threatening food supplies, protecting or damaging homes and environments, and influencing water and air quality. Public health impacts are thus shaped by the context and scale of landscape fires and the direct and indirect pathways for their impacts on people. This presentation will discuss a range of scenarios, from planned burning to severe wildfire disasters, to illustrate the main ways in which landscape fires influence both the physical and mental health of people and societies.

How to cite: Johnston, F.: Landscape fires and public health, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20475, https://doi.org/10.5194/egusphere-egu2020-20475, 2020.

Elevated fire activity in 2019 across the arctic, Amazon, Australia, and other regions sparked a discussion about the role of climate change for the recent rise in biomass burning.  Given that drivers of fire vary widely between different fire types and regions, interpreting trends requires a regional breakdown of the global pattern. Our Global Fire Emissions Database (GFED) now provides nearly 25 years of consistent data and offers important insights into changing fire activity. The GFED record captures a global decline in burned area, driven mostly by reductions in savanna fires from fragmentation and land use change. The global declining trend is therefore driven by areas with relatively low fuel loads where fire often decreases during drought.  Here, we report on increasing fire trends in several other regions, which become even more apparent when proxy data from before the satellite era are included. Increasing trends are concentrated in areas with higher fuel loads that burn more easily under drought conditions, and where warming leads to increasing vapor pressure deficits that contribute to more extreme fire weather and higher combustion completeness values. Therefore, the rate of decline in fire emissions is less pronounced than that in burned area, and emissions of several reduced gases have actually increased over time. The historic time series provides important context for trends and drivers of regions that burned extensively in 2019, and moving beyond burned area to estimate fire emissions of greenhouse gases and aerosols is critical to assess how these events may feed back on climate change if trends continue.     

How to cite: van der Werf, G., Randerson, J., Giglio, L., van Wees, D., Andela, N., Veraverbeke, S., Morton, D., and Chen, Y.: Fire - climate interactions in a warming world, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10974, https://doi.org/10.5194/egusphere-egu2020-10974, 2020.

Fire and vegetation have a dual interaction with each other, whilst also both influencing the environment and atmosphere. For example, fire regimes are themselves controlled by atmospheric conditions, atmospheric composition, climate and the type of vegetation. Whilst, the effects of fires, the products and emissions they generate influence biogeochemical cycles and long-term Earth system processes through their impacts on nutrient cycles and by altering the composition and distribution of biomes. Hence fire is more than a simple agent of disturbance and has a multitude of complex feedbacks.

Wildfires have shaped our ecosystems and Earth system processes for some 420 million years. For example the presence of and changes in fire frequency and behaviour on evolutionary timescales has influenced the physiological traits of plants such that many ecologists have interpreted them as adaptations to fire. For example, serotiny in the Pine lineage is believed to have evolved millions of years ago in the Late Cretaceous period, where wildfires were both frequent and intense. Such traits seemingly continue to allow some plants to succeed in fire prone areas. However, humans have entirely altered ignition patterns, with some 95% of fires being started by man; we have altered the connectivity of fuels in landscapes, species composition and fuel structure. Yet we have limited understanding to what extent we have disrupted fire feedbacks to the Earth system. This lies in large part because we have not yet well understood what natural feedbacks fire has had on our planet throughout its history.

In this talk I will explore some of the critical history of fire and some of the processes that fire appears to regulate in order to pose the question - are fires a critical resource that secures the long-term balance of the Earth system that keeps our planet habitable to man?

How to cite: Belcher, C.: Quantifying the Pyrocene: How Important is Fire to Life on Earth? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6816, https://doi.org/10.5194/egusphere-egu2020-6816, 2020.

Vegetation fires are a global phenomenon that affect 3-5 million km² every year. Both natural and caused by humans, fire burns through a very broad range of ecosystems, from boreal forest to tropical savannahs, exerting also a very broad range of effects. Despite this huge variability, there are two components always present after a fire: charcoal and ash.

Charcoal, also known as pyrogenic carbon, is a key player in the carbon cycle from fires, due to its ability to act as a carbon sink. In addition, it can play a major role in the functioning of soils via its interactions with other elements and priming of native soil organic matter. Meanwhile, ash, the powdery fire residue, can be an important source of nutrients for the post-fire regrowing vegetation, but it can also be a source of water contamination when transported by wind and water to the hydrological networks after fire. This presentation will give an overview on the current knowledge of these two interlinked components of the wildfire-affected landscapes, highlighting current gaps and future research directions.

How to cite: Santin, C., Jones, M. W., Neris, J., and Doerr, S. H.: After the fire: biogeochemical effects of charcoal and ash on fire-affected landscapes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9433, https://doi.org/10.5194/egusphere-egu2020-9433, 2020.

Fire is a globally relevant natural or anthropogenic phenomenon with a rapidly increasing importance in the era of the climate change. In each year, approximately 4% of the global land surface burns. For effective ecosystem conservation, we need to understand fire regimes, identify potential threats, and also the possibilities in the application of prescribed burning for maintaining ecosystems.

Here I provide an overview on the contradictory role of fire in nature conservation from two continents with contrasting fire histories, focusing on European and North-American grasslands. I show that the ecological effects of fire depend on the fire regime, fire history, ecosystem properties and the socio-economic environment. Catastrophic wildfires, arson, too frequent or improperly planned human-induced fire often lead to the degradation of the ecosystems, the disappearance of rare plant and animal species, and to the encroachment of weed and invasive species. I illustrate with examples that these negative fire effects act synergistically with the human-induced changes in land use systems.

I also underline with case studies that in both regions, properly designed and controlled prescribed burning regimes can aid the understanding and managing disturbance-dependent ecosystems. Conservation in these dynamic and complex ecosystems is far more than fencing and hoping to exclude disturbance; but the contrary: disturbance is needed for ecosystem functioning. Therefore, the conservation of dynamic, diverse and functioning ecosystems often require drastic interventions and an unconventional conservation attitude. However, the expanding urban-wildlife interface makes the application of prescribed burning challenging worldwide. A major message for the future is about fire policy: it is crucial to moderate the negative effects of fire, however, properly designed prescribed burning should be used as a tool for managing and conserving disturbance-dependent ecosystems.

How to cite: Valkó, O.: The contradictory role of fire from the nature conservation perspective, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10518, https://doi.org/10.5194/egusphere-egu2020-10518, 2020.