Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

Abstract

Biomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

Large Air Quality and Public Health Impacts due to Amazonian Deforestation Fires in 2019

“…Since 2012, rates of deforestation across the BLA have increased by a factor of two, with 10 129 km 2 deforested in 2019 (Barlow et al, 2019;Assis et al, 2019). The impact of this increased deforestation on the amount of fire is still uncertain (Libonati et al, 2021;van Marle et al, 2017;Aragão et al, 2018) and the impacts on air quality have not yet been fully assessed. To estimate the impact of increased deforestation on fire, we developed a model to predict dry season active fire count based on climate and deforestation.…”

Spatio-temporal patterns of extreme fires in Amazonian forests

“…Jiménez-Muñoz et al [49] found that up to 13% of Amazonian tropical forests endured extreme drought at the beginning of 2016, which set the conditions for more extreme forest fires in 2017. On the other hand, the year 2013 was classified as exceptionally wet based on the positive rainfall anomalies and a short dry season [11]. These conditions did not promote high intensity forest fires and therefore, we observed the lowest number of extreme fires (179 events, Fig.…”

“…The establishment and enforcement of the Action Plan to Prevent and Control Deforestation in the Brazilian Legal Amazon (PPCDAm) in 2004, together with the Soy Moratorium in 2006, and the Zero-Deforestation Cattle Agreements in 2009 allowed to progressively reduce deforestation rates from 2005 onwards [9,10]. While the use of fire in deforestation was an accepted paradigm for a long time, Aragão et al [11] suggested a decoupling a e-mail: canocrespoana@gmail.com (corresponding author) between deforestation and fire because the decrease in fire activity was not as strong as the decline in deforestation during the period 2003-2015. However, Libonati et al [12] revisited the decoupling hypothesis recently and found a much weaker decoupling for the same period, which consequently reinforces the role of deforestation as a major driver of fire in Amazonia.…”

Analysis of fire risk in the Amazon: a systematic review

“…Among these dysfunctions, we highlight the transformations in its landscape promoted by government policies to encourage the occupation of the region, the expansion of agricultural activity and the construction of major infrastructure works such as highways and hydroelectric dams; actions that have historically promoted deforestation in the Amazon (Cochrane, 2003;Becker, 2005;Fearnside, 2006;Ferrante and Fearnside, 2020;Libonati et al, 2021).…”

“…Given the gap in knowledge about the inflection point of the forest, as a precautionary measure strong efforts should be made to conserve the Amazon Forest yet standing (Fearnside, 2009;Nobre and Borma, 2009). However, the number of fires in the Amazon has intensified in recent years, driven by the increase in deforestation (Silveira et al, 2020;Libonati et al, 2021). About 1/3 of the fire occurrences between 2003 and 2019 occurred up to 1 km away from deforested areas in the same year and up to 500 m from deforested areas in the previous year; in 2019, fires occurred Rev.…”