14 February 2018

Forest fires during droughts are major source of Amazonian carbon emissions, a study in Nature Communications reveals

Extreme droughts in the Brazilian Amazon are causing forest fires that release significant carbon emissions, the study shows.

Despite significant achievements by the Brazilian authorities in curbing carbon emissions from deforestation, these gains could be undermined by repeated droughts in the 21st Century.

A team of researchers from 12 institutions including the Brazilian National Institute for Space Research, the Brazilian Monitoring Centre for Natural Disaster Alert, and Lancaster University, used satellite data and greenhouse gas inventories to assess drought impacts on fire incidence and associated carbon emissions between 2003 and 2015 in the Brazilian Amazon.

They found that despite a 76 per cent decline in deforestation rates over the past 13 years, fire incidence increased by 36 per cent during the 2015 drought compared to the preceding 12 years. They estimate that forest fires during drought years contribute emissions of one billion tonnes of CO2 annually to the atmosphere. This is more than half of the emissions released from old-growth forest deforestation.

According to Luiz Aragão a scientist from the Brazilian National Institute for Space Research (INPE) and lead author of the article, this is the first time that scientists have clearly demonstrated how forest fires can become widely spread during recent droughts and how much they influence Amazonian carbon emissions in a decadal scale.

He emphasises that satellites currently in operation allows the retrieval of data on current climate, atmospheric carbon content and the status of terrestrial ecosystems. The combination of such data is permitting Dr Aragao’s research laboratory at INPE to develop robust methodologies for understanding and accounting for carbon emissions from forest degradation, one of the bottle necks for accurately monitoring, verifying and reporting the Amazonian carbon budget.

“Lessons learned with this study are important because some observations and models indicate that the intensity and frequency of droughts in Amazonia may increase as a consequence of climate change and deforestation”, explains Jose Marengo from the Brazilian Monitoring Center for Natural Disaster Alert (CEMADEN).

Dr Marengo adds that “three ‘droughts of the century’ in 2005, 2010, 2015/2016, have occurred in the region due to a warmer tropical North Atlantic ocean or to El Nino, and the intensification of these phenomena in the future favours more droughts.”

Dr Liana Anderson, also from CEMADEN, says: “If changes in the near future climate are consistent with model results and no policy actions are taken to efficiently predict and avoid fire occurrence, we expect that carbon emissions from forest fires would be sustained in an analogue way as demonstrated by our study.”  

The study highlights that Brazil has made substantive advances to report emissions from deforestation, however, based on the results, researchers believe Brazil needs urgently to focus on incorporating into estimates CO2 losses associated with fires unrelated to the deforestation process.

They argue that governments must be aware of these values to propose realistic and effective solutions to maintain low deforestation levels, find new practices of land management that curb fire incidence and the associated carbon emissions and loss of biodiversity.

“It is critically important to implement sustainable and socially-just policy responses,” said Professor Jos Barlow from Lancaster University, and a co-author of this study. “Although most of the ignition sources for wildfires come from small-scale agriculture, fire is an essential part of many smallholders’ livelihoods, and forest flammability has been increased by other drivers beyond their control including the timber trade and anthropogenic climate change.

“A broad suite of action is therefore required, including improving the fire combat capacity of tropical forest countries, avoiding logging in fire-sensitive regions, and co-developing climate-safe agricultural practices with smallholders.”

Read Jos Barlow’s article about this research in the Conversation


Reference: Aragão et al. (2018) 21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions. Nature Communications. DOI: 10.1038/s41467-017-02771-y