Leverhulme Wildfires Centre Leverhulme Wildfires Centre

High-latitude fires and the future of Earth’s climate

In high-latitude regions, larger and more frequent fires have been documented over the last years, and it is expected to increase further due to warmer temperatures and decreased precipitation imposed by climate change (IPCC,2019). Boreal wildfires in general are a significant source of CO2 emissions, as well as other, greenhouse gases (Akagi et al. 2011; Van Der Werf et al. 2010), e.g. emissions from boreal forests between 1997 and 2016 accounted for 7.4% of the global emissions (van der Werf et al. 2017).

The effect of boreal fires on the future climate has not been investigated and is of great importance since climate change is occurring more rapidly in those high-latitude areas. More flammable forests in addition to the large carbon-rich peatlands, will potentially lead to devastating consequences for our climate.

In our project, the combination of satellite data and earth system models will create an innovative methodological framework for the study of wildfires. More precisely, we will first characterize the state of the atmosphere and climate based on past and present wildfire conditions. The future impact of wildfires will be investigated, employing modeling, observations and new analysis tools.

Figure 1. Hundreds of fires burning across Siberia on 30th July 2019, and the smoke produced heading towards North America (source: NASA). The summer of 2020 featured even more intense burning.  https://www.nasa.gov/image-feature/goddard/2019/siberian-smoke-heading-towards-us-andcanada

 

 

References

  • IPCC,2019: Jia, G., E. Shevliakova, P. Artaxo, N. De Noblet-Ducoudré, R. Houghton, J. House, K. Kitajima, C. Lennard, A. Popp, A. Sirin, R. Sukumar, L. Verchot, 2019: Land–climate interactions. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems [P.R. Shukla, J. Skea, E. Calvo Buendia, V. Masson-Delmotte, H.-O. Pörtner, D.C. Roberts, P. Zhai, R. Slade, S. Connors, R. van Diemen, M. Ferrat, E. Haughey, S. Luz, S. Neogi, M. Pathak, J. Petzold, J. Portugal Pereira, P. Vyas, E. Huntley, K. Kissick, M, Belkacemi, J. Malley, (eds.)]. In press.
  • Akagi, S.K. et al., 2011: Emission factors for open and domestic biomass burning for use in atmospheric models. Atmos. Chem. Phys., 11, 4039–4072, doi:10.5194/acp-11-4039-2011.
  • Van Der Werf, G.R. et al., 2010: Global fire emissions and the contribution of deforestation, savanna, forest, agricultural, and peat fires (1997–2009). Atmos. Chem. Phys., 10, 11707–11735, doi:10.5194/acp-10-11707-2010.
  • Van Der Werf, G.R. et al., 2010: Global fire emissions and the contribution of deforestation, savanna, forest, agricultural, and peat fires (1997–2009). Atmos. Chem. Phys., 10, 11707–11735, doi:10.5194/acp-10-11707-2010.

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Recent Arctic wildfires have burned previously unheard-of expanses of land and released significant amounts of prehistoric carbon into the atmosphere through smouldering fire. Due to their remote location and insufficient thermal signature, Arctic fires are poorly understood and challenging to detect. We are working on this project in order to understanding of the smouldering fire in this area can be beneficial to develop prevention and mitigation strategies.

Due to the persistent nature of the smouldering phenomena, smouldering wildfires pose a different threat from flaming fire. There have been instances where fires started in the summer continued to burn underground throughout the winter and then surfaced once the snow had melted [1]. Such fires that reappear after the winter season is through are known as zombie fires, since it once seemed that they were extinct in the autumn and then reappear in the spring [2]. However, they are more frequently referred to as holdover fires or overwintering fires (Fig. 1) [3, 4]

Figure 1. Illustration of the overwintering wildfire: the survival of the smouldering fires over winter which re-emerge during the arrival of spring (Rein and Huang 2021).

 

 

 

References:

[1] Jandt R, Thoman R (2020) The “Zombie” Fires of 1942.

[2] Vaughan BA (2020) ’ Zombie ’ fires are burning the Arctic after smouldering under snow. New Sci. 1–5.

[3] Rein G, Huang X (2021) Smouldering wildfires in peatlands, forests and the arctic: Challenges and perspectives. Current Opinion in Environmental Science & Health 24, 100296.

[4] Scholten R, Veraverbeke S (2020) Fires can overwinter in boreal forests of North America doi:10.5194/egusphere-egu2020-6013.

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The extent on anthropogenic influence on fire regimes throughout the Holocene period is currently an open question. Whereas global and regional studies tend to emphasise the primacy of climate changes on fire regimes, more localised or sub-regional studies have highlighted human influences as essential in explaining the patterns of reconstructed fire history.

The main objective of this research is to investigate the relationship between land-use change and fire regimes during the Holocene. To that end the project will make use of a variety of data sources, including charcoal datasets, other palaeoecological datasets (e.g. pollen), and archaeological radiocarbon datasets, and statistically analysing and modelling the spatiotemporal relationships between these elements. Ultimately, an improved understanding of the relationship between fire and land-use change using palaeo-data will help in our ability to predict how these important components in the earth system will change in the future.

At present, the research is focussed on exploring the relationship between sedimentary charcoal records of fire history and a  radiocarbon-based proxy of population density in Iberia during the early to mid Holocene.

This project is also supervised by Marc Vander Linden – Department of Archaeology & Anthropology, Bournemouth University

Project duration: 2020-2024

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Landscape burnings, including wildfires and fires purposely lit for clearing or managing land, are widespread globally, occurring in almost all vegetated biomes worldwide. It releases large amount of smoke, which is composed of a mix of gases and particulates. These smoke emissions may have significant effects on insects.

The first part of this PhD project, which has culminated in the first paper of the PhD, titled “Strong impacts of smoke polluted air demonstrated on the flight behaviour of the painted lady butterfly (Vanessa cardui L.)”, aims to examine the behaviour of adult V. cardui flying in different levels of combustion-generated airborne PM2.5, comparison this to flying under ‘clean air’ conditions. Result showed that V. cardui flying in smoke-contaminated air significantly affected their flight behaviour, and we found a strong negative correlation between flight speed and the concentration of fine particulate matter (PM2.5).

The second experiment has continued to examine the behaviour of adult V. cardui, but flying in more realistic smoke environment for longer period (6 hours), and investigating whether particles or gaseous emissions from smoke impact on V. cardui. This experiment provided more information how smoke from landscape burning impact butterfly migration.

This project is also co-supervised by Dr Robert Francis (KCL)

Blog article here

 

 

 

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Peat fires are some of the largest and most persistent fires on Earth. Globally peatlands store approximately 25% of the World’s soil carbon, and therefore fires in these areas threaten to release large amounts of carbon. Large peat fires have been seen in both the tropics, for example the 1997/98 peat fires in Indonesia, as well as in the northern high latitudes. Peat fires release large quantities of carbon dioxide, other greenhouse gases and aerosols, which have wide ranging implications on the climate system, air quality and ecosystems. Peat fires at present are not explicitly incorporated into the INFERNO fire model, and only one Earth system model currently includes them. Therefore, this PhD aims to build a peat fire parametrisation into INFERNO, in order to assess the effects of peat fires on atmospheric composition, the carbon cycle, air quality and climate. This PhD also aims to be able to better represent burnt area in peatland dominated locations, as well as improving estimations of fire emissions.

This PhD receives funding and support from the Met Office, and is co-supervised by Chantelle Burton (Met Office).

Figure References:

Van der Werf, G. R., et al., 2017. Global fire emissions estimates during 1997-2016. Earth System Science Data. 9, 697-720. https://doi.org/10.5194/essd-9-697-2017
Hugelius, G., et al., 2020. Maps of northern peatland extent, depth, carbon storage and nitrogen storage. Dataset version 1.0. Bolin Centre Database. https://doi.org/10.17043/hugelius-2020

Cover image: Smoldering peat fire by U. S. Fish and Wildlife Service – Northeast Region

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Recent studies have shown that temperature and precipitation in the Mediterranean are expected to change, indicating longer and more intense summer droughts that even extend out of season. In connection to this, the frequency of forest fire occurrence and intensity will likely increase.

This PhD project is therefore assessing the changes in future fire danger conditions for the different regions of Greece using the Canadian Fire Weather Index (FWI), utilizing gridded future climate outputs, estimated from six regional climate models from the Coordinated Regional Downscaling Experiment (CORDEX).

The study uses three Representative Concentration Pathways (RCPs) consisting of:

  1. an optimistic emissions scenario where emissions peak and decline beyond 2020 (RCP2.6);
  2. a mid-of-the-road scenario (RCP4.5);
  3. and a pessimistic scenario, in terms of mitigation, where emissions continue to rise throughout the century (RCP8.5).

The FWI projections were assessed for two future time periods, 2021-2050 and 2071-2100, comparing to a reference time period in the recent past 1971-2000. Based on established critical fire risk threshold values for Greece, the future change in days with critical fire risk were calculated for different Greek domains.

The results show that future fire danger is expected to progressively increase in the future, especially in the high-end climate change scenario, with southern and eastern regions of Greece exhibiting increases in the FWI that exceed 20 FWI units, on average.

Furthermore, southern Crete, the Aegean Islands, the Attica region, as well as parts of eastern and southern Peloponnese are predicted to experience a larger increase in the fire danger, with an additional 12-17 potential fire days in the distant future (2070-2100) when compared to the reference period, under the RCP8.5 scenario.

Figure: Difference in the annual ensemble mean number of days (NOD) with FWI>30 between the future periods (for all future scenarios) and the reference period. The left column corresponds to the difference for the near future period [(2020-2050) – (1970-2000)] and the right column to the difference for the distant future [(2070-2100) – (1970-2000)].

Also involved in the study: Christos Giannakopoulos and Anna Karali from the Institute for Environmental Research and Sustainable Development, National Observatory of Athens; Robert Field from the Department of Applied Physics and Applied Mathematics, Columbia University; and Mihalis Lazaridis and Kostadinos Seiradakis from the School of Environmental Engineering, Technical University of Crete.

 

Cover image: Varnavas, Greece, 2009, by Filippos Sdralias

 

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The northern extratropics has experienced increases in fire activity in recent decades, which have had important consequences for ecosystems, carbon cycling and human societies. There is currently wide uncertainty in predictions of how fire will respond to climate changes in this region in the coming decades. Studying fire responses over palaeo timescales provides a window into how fire may respond to large environmental changes, which are anticipated to play out over the course of this century. This project will leverage a newly-created global palaeo charcoal database, the Reading Palaeofire Database, to reconstruct changes in biomass burning across the circum-northern extratropics over the Holocene. It will attempt to explain patterns in fire activity over millennia in this region by quantitatively linking sub-continental scale fire responses to climate, vegetation and human-induced landscape shifts. This will provide novel insights into the importance of various environmental reorganisations in shaping fire regimes, which can directly contribute to attempts at better constraining predictions of future changes in wildfire patterns.

Project Duration: 2019-2023

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Wildfires and other forms of landscape burning are complex, dynamic and in some ways difficult to predict and certainly potentially dangerous phenomena. Fires up to even extreme mega-fire events can be studied using the techniques of remote sensing and modelling, but these studies and those of smaller burns often need to be informed by and sometimes combined with data from in situ investigations, for example on the spectral properties of the fires if using remote sensing and on the different composition of their smoke and what controls that if estimating emissions. This in situ data can be collected in the field on planned burns or even on wildfires were possible, and can also be supplemented – where appropriate – by data collected in laboratory fires under more controlled conditions. The purpose of this technical postdoctoral project is to deliver the capability to make and analyse these measurements to support specific aspects of the Centre’s work on fire spectral signatures and smoke emissions, as well as wider investigations.

Project duration: 2019- ongoing

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Wildfires and other forms of landscape burning turn solid material held in vegetation and organic soil into a complex mix of airborne gases and particulates. When conducted over large areas and/or in extreme fires, this rapid process can result in massive atmospheric impacts, perhaps most particularly on air quality (AQ). Landscape fires of this sort are thus responsible for severe AQ episodes, including some of the world’s worst events that likely impact the health of millions. Furthermore, in many regions of the developing world recurrent burning of agricultural waste over huge areas of croplands leads to air pollution episodes that routinely affect the air that hundreds of millions of people breath, including in some of the largest mega-cities on Earth. However, it can be hard to disentangle the contribution landscape fires make to the poor air quality of these areas because many of the areas affected suffer from a paucity of in situ atmospheric measurements for example. Regional AQ modelling can deploy state-of-the-art information on different emissions sources, including landscape fires and agricultural burning, to address these and other related questions, ultimately informing studies of human health and also potentially agricultural policy development related to changing patterns and timing of cropping. Other uses of such modelling include the study of the radiative effects of the short-lived climate impactors (SLCPs) and to support the evaluation and validation of new fire emissions estimates coming from Earth Observation – which are extremely difficult to validate directly or through other means but which when placed within a regional AQ model can provide metrics such as aerosol optical depth timeseries that can be compared to high accuracy in situ data.

Project duration: 2021-2025

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