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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2020-123
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2020-123
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: technical note 11 May 2020

Submitted as: technical note | 11 May 2020

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This preprint is currently under review for the journal BG.

Technical note: Low meteorological influence found in 2019 Amazonia fires

Douglas I. Kelley1, Chantelle Burton2, Chris Huntingford1, Megan A. J. Brown1,3, Rhys Whitley4, and Ning Dong5 Douglas I. Kelley et al.
  • 1UK Centre for Ecology & Hydrology, Wallingford, Oxfordshire, OX10 8BB, UK
  • 2Met Office Hadley Centre, Fitzroy Road, Exeter, EX1 3PB, UK
  • 3School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
  • 4Natural Perils Pricing, Commercial and Consumer Portfolio and Product, Suncorp Group, Sydney, Australia
  • 5Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia

Abstract. The sudden increase in Amazon fires early in the 2019 fire season made global headlines. While it has been heavily speculated that the fires were caused by deliberate human ignitions or human-induced landscape changes, there have also been suggestions that meteorological conditions could have played a role. Here, we ask two questions: were the 2019 fires in the Amazon unprecedented in the historical record?; and did the meteorological conditions contribute to the increased burning? To answer this, we take advantage of a recently developed modelling framework which optimizes a simple burnt area model, and whose outputs are described as probability densities. This allowed us to test the probability of the 2019 fire season occurring due to meteorological conditions alone. We show that the burnt area was indeed higher than previous years in regions where there is already substantial deforestation activity in the Amazon, with 11 % of the area recording the highest early season (June–August) burnt area since the start of our observational record. However, areas outside of the regions of widespread deforestation show less burnt area than the historical average, and the optimized model shows that there is a 71 % probability that this low burned area would have been expected over the entire Amazon region, including regions already witnessing deforestation and of high fire occurrence in 2019. We show that there is a < 7 % chance of the observed June–August fires being caused by meteorological conditions alone, decreasing to < 1 % in Paraguay and Bolivia dry-forests and at the eastern end of the Amazons arc of deforestation. This suggests that changes in land use and land cover or land management are the likely drivers of the large increase in the 2019 early fire season burnt area. Burnt area for the peak of the fire season in September returned to levels expected from meteorology conditions in the arc of deforestation, potentially coinciding with a shift in policy from South American governments, but remained high in Bolivia and Paraguay.

Douglas I. Kelley et al.

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Status: open (until 27 Jun 2020)
Status: open (until 27 Jun 2020)
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Douglas I. Kelley et al.

Data sets

ConFire Model input/output for South America D. Kelley, R. Whitley, C. Burton, M. Brown, C. Huntingford, and N. Dong https://doi.org/10.5281/zenodo.3817467

Model code and software

Scripts used in the submission of "Low Climatic Influence found in 2019 Amazonia Fires" D. Kelley, R. Whitley, M. A. J. Brown, and C. Burton https://doi.org/10.5281/zenodo.3817456

Douglas I. Kelley et al.

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Latest update: 03 Jun 2020
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Short summary
Initial evidence suggests human ignitions or landscape changes caused most Amazon fires during August 2019. However, confirmation is needed that meteorological conditions did not also have a substantial role. Assessing the influence of historical weather on fire frequency, and in an uncertainty framework, we find that 2019 meteorological conditions alone would have meant fewer-than-usual fires. We conclude socio-economic factors likely had a strong role in the high recorded 2019 fire activity.
Initial evidence suggests human ignitions or landscape changes caused most Amazon fires during...
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