Tackling global wildfires with satellite data

The Innovation Platform speaks to Global Forest Watch about the latest in global wildfire research through satellite data, technology and tools.

Recent years have been plagued by record setting wildfires around the globe. From Indonesia’s devastating peat fires in 2015 to last summer’s fire outbreak in the Brazilian Amazon to the ongoing brushfires in South Eastern Australia, large-scale fires have become both a significant climate concern and a matter of public health and safety. As climate change increases the likelihood of fire-prone conditions, better ways of tackling wildfire detection and response are becoming more urgent. In order to get a handle on the scope of the issue, policy makers, businesses and communities are turning to satellite-derived data.

How do wildfires start?

The first step is understanding the complex role that fires play in forest ecosystems. In more northern latitudes, fires are part of the natural cycle of death and re-growth. Annual fire regimes support species turnover and some evergreen tree species depend on fire to open hard cones and release their seeds. Most natural fires are sparked by lightning strikes, which a recent NASA study found have been increasing in the boreal region since 1975.1 The study also found that record numbers of lightning strikes correlate to greater numbers of fires and years with abnormally large total burned areas. Projections predict that the number of lightning strikes globally will continue to increase with climate change, by an estimate of 12% with every degree of atmospheric warming.2

In tropical latitudes, natural fires are much rarer because of their naturally high moisture. Fires in rainforests are nearly all human caused. Analysis of NASA fire alerts from the 2019 Brazilian Amazon fires indicated most fires were burning on privately owned land and alerts tended to cluster around roads and farms.3,4 These fires are either set illegally by farmers to clear rainforest for agriculture, or accidentally when fires clearing pasture or cropland escape into the forest. Logging and agriculture can often degrade rainforests, drying them out and making them more susceptible to runaway burning.5 In 2018 (most recent available data), Brazil lost 1.35 million hectares of tropical primary forests, most of which were a result of clear cutting in the Amazon.6 This loss plays into a feedback loop— more clearcutting will lead to more fire-prone forests, which will in turn lead to more forest lost from runaway fires.

Fires have far-reaching impacts on people and the environment

Both natural and human-caused fires represent a serious climate concern. When fires burn through forests, they incinerate organic matter that stores thousands of tons of carbon— some of which has been locked in the soil and tree trunks for centuries.7 The more frequent and intense fires become, the more carbon they release, accelerating warming. Indonesia experienced a record-breaking fire crisis in 2015; with the majority of fires burning on carbon-rich peat soil, Indonesia’s daily emissions from fires alone surpassed that of the United States’ economy.8

Fires also destroy valuable carbon sinks. World Resources Institute research found that forests could provide 23% of the carbon mitigation needed to keep global warming under 2°.9 When forests are destroyed by fire, it can take decades for them to regenerate back to their prior carbon sequestration potential. While some forest systems are spurred to new growth by burning, more frequent fires can also inhibit regeneration, killing young trees before they’ve produced enough seeds to replace themselves. Over time this can alter species compositions, reduce suitable animal habitat and shift an ecosystem from forest to open plains.10

Wildfires are not only a matter of environmental destruction, but also public health. In Indonesia’s 2015 fire crisis, smog and haze drifted across the Strait of Malacca to Singapore, causing the country’s highest level of air pollutants to date.11 Air pollution is the fifth leading risk factor for mortality worldwide and is linked to health complications including heart disease, chronic respiratory diseases, lung infections, cancer and a life expectancy reduced by an average of nearly two years.12 When air quality worsens over a population it can be nearly impossible for residents to avoid breathing in the harmful particulates.

Satellite data to track fires as they unfold

Faced with the urgent consequences of wildfires and knowing that the threat will likely increase with climate change, decision-makers are looking to all sectors for solutions. Satellite technology offers a near-real–time picture of active fires, aiding monitoring efforts. GFW Fires is one online platform that allows users to monitor fires around the world in near-real-time. The openly accessible platform pulls data from NASA’s MODIS and VIIRS satellites which orbit the earth several times each day searching for “temperature anomalies”. VIIRS can detect a spike in temperature in an area as small as five square meters.13 Each red pinprick on the map indicates an area (375 meters for VIIRS and one kilometre for MODIS) in which one or more of these anomalies has been detected.

Moreover, because of VIIRS’ higher resolution, it can provide a more precise visual of fires as they unfold in real time. However, MODIS satellites have been orbiting for much longer (VIIRS launched in 2012 and MODIS has been operating since 2000) granting a vital picture of long-term fire trends. Comparing fire seasons to past years throws out-of-the-ordinary years into sharp relief. For example, GFW data shows that the recent fires in New South Wales, Australia were nearly quadruple the region’s typical yearly fire count, making 2019 the worst fire season in recorded history. This context is crucial, especially in temperate woodlands or boreal forests where fires can be a natural feature of the landscape.

The fire reporting feature provides even more context, generating quick graphics that indicate how many alerts were detected in protected areas, crucial intact and primary forests, areas of logging or oil palm plantations. Fire alerts are also available on the main GFW platform, which allows viewers to overlay fire alerts with forest loss datasets, identify the association between fire alerts and deforestation alerts and take advantage of high resolution satellite imagery which provides a sharp picture of the burned area.

What the fire alerts don’t do is provide a one-to-one equivalence with the number of fires burning. A cluster of several alerts could indicate one large fire spreading out over the landscape, and within the resolution of one single alert, more than one small fire may have registered. Sometimes other events like volcanic eruption or heat flashing off of metal surfaces will get picked up by the satellites. Rather, fire alerts provide an “at-a-glance” view of the magnitude of a fire season.

From monitoring changes to changing the game

Fire alerts play a critical role in early detection of fires, which is often the best way to minimise damage both to the environment and peoples’ property. Government agencies, private companies and local communities can employ GFW fires to keep an eye on active fires, prioritise emergency response and ensure public safety.

Sudameris, an investment bank in Paraguay, has been using fire alerts to monitor their clients’ land since 2016. When alerts came through on one of the ranches they had investments in, they called to notify the landowner. Although the rancher had lost 100 hectares of pastureland in the fire, they were able to save the other 1,200 hectares and their herd, and Sudameris was able to safeguard their investment. A community group in Indonesia is using the alerts in a similar way. The Women Research Institute is working to set up an early warning system for communities in Riau that disseminates information on fires burning in the area and warns community members when to stay inside or evacuate to a designated safe space.14 As fires become more frequent in a warmer world, response times will need to be as quick and precise as possible. Having accurate, up-to-date fires data is just the first step.


  1. Veraverbeke, S., Rogers, B.M., and Goulden, M.L. et al. 2017. Lightning as a major driver of recent large fire years in North American boreal forests. Available at: https://www.nature.com/articles/nclimate3329
  2. Romps, D.W., Steeley, J.T., and Vollaro, D. et al. 2014. Projected increase in lightning strikes in the United States due to global warming. Available at: https://science.sciencemag.org/content/346/6211/851
  3. Amaral, L., Matsumoto, M., and Munroe, T. 2019. Brazil’s Fire Ban Correlates a Reduction in Amazon Wildfires. The Ban Lifts Today. Available at: https://blog.globalforestwatch.org/fires/brazils-fire-ban-correlates-a-reduction-in-amazon-wildfires-the-ban-lifts-today
  4. Weisse, M., and Ruiz, S. 2019. What Can Global Forest Watch Tell Us About The Fires in Brazil. Available at: https://blog.globalforestwatch.org/fires/what-can-global-forest-watch-tell-us-about-the-fires-in-brazil
  5. Cochrane, M.A., and Laurance, W.F. 2008. Synergisms among Fire, Land Use, and Climate Change in the Amazon. Royal Swedish Academy of Sciences 2009. Ambio Vol. 37, No 7-8, December 2008.
  6. Weisse, M., and Goldman, L. 2019. The World Lost a Belgium-sized Area of Primary Rainforests Last Year. Available at: https://blog.globalforestwatch.org/data-and-research/world-lost-belgium-sized-area-of-primary-rainforests-last-year
  7. https://www.eurekalert.org/pub_releases/2019-08/uos-mfw082119.php
  8. Harris, N., Minnemyer, S., and Stolle, F. et al. 2015. Indonesia’s Fire Outbreaks Producing More Daily Emissions than Entire U.S. Economy. Available at: https://blog.globalforestwatch.org/fires/indonesias-fire-outbreaks-producing-more-daily-emissions-than-entire-u-s-economy
  9. Gibbs, D., Harris, N., and Seymour, F. 2018. By the Numbers: The Value of Tropical Forests in the Climate Change Equation. Available at: https://blog.globalforestwatch.org/climate/by-the-numbers-the-value-of-tropical-forests-in-the-climate-change-equation
  10. https://theconversation.com/more-frequent-fires-could-dramatically-alter-boreal-forests-and-emit-more-carbon-122355#:~:targetText=Impacts%20of%20more%20frequent%20fire&targetText=Recent%20estimates%20suggest%20that%20boreal,that%20carbon%20found%20in%20soils.&targetText=Increasing%20fire%20frequency%20thus%20makes,carbon%20back%20to%20the%20atmosphere.
  11. Minnemeyer, S. 2015. Indonesian Fires Create “Hazardous” Levels of Air Pollution in Singapore. Available at: https://blog.globalforestwatch.org/fires/indonesian-fires-create-hazardous-levels-of-air-pollution-in-singapore
  12. Health Effects Institute. 2019. State of Global Air 2019. Special Report. Boston, MA:Health Effects Institute. ISSN 2578-6873
  13. Minnemeyer, S., Sargent, S., and Weisse, M. 2016. Fighting fires with satellites: VIIRS fire data now available on Global Forest Watch. Available at: https://blog.globalforestwatch.org/fires/fighting-fires-with-satellites-viirs-fire-data-now-available-on-global-forest-watch
  14. Naval, C., and Ruiz, S. 2019. Women Research Institute Blazes Path Towards Fire Safety in Riau Communities. Available at: https://blog.globalforestwatch.org/people/women-research-institute-blazes-path-towards-fire-safety-in-riau-communities

Sarah Ruiz
Junior Writer/Editor Global Forest Watch
World Resources Institute
Tweet @globalforests

Please note, this article will also appear in the first edition of our new quarterly publication.

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