Brazil has changed. As well as the COVID-19 pandemic killing more than 170,000 of its citizens so far, 2020 has seen almost one-third of the Pantanal, the largest tropical wetland in the world, on fire. Four million hectares of forest, savannah and shrub-land (an area bigger than the US state of Maryland) have gone up in flames since January (see go.nature.com/2jtw6va). Almost all the Indigenous territories and conservation facilities were burnt, as was much private land. Conservation areas such as Encontro das Águas State Park have been devastated — it contained one of the largest populations of jaguars in the world.

Fires’ impacts have been felt nationwide. Smoke has spread thousands of kilometres, reducing air quality in São Paulo, Rio de Janeiro and Curitiba. Southern states have experienced showers of black rain. The fires are decimating Brazil’s economy, curbing inward investment as well as sectors such as air travel and tourism that are already hit hard by the pandemic.

The public is worried. The fires have made the headlines for months. Thousands of Brazilians have volunteered to fight the flames, rescue wildlife or donate money. Yet, Brazil’s government is doing little. It is ignoring the causes of the fires: a combination of inadequate fire management, climate extremes, human behaviour and weak environmental regulations. Worse, it has slashed funding for fire prevention and has been slow to contract firefighters. It has even cast doubts on the reliability of satellite fire detections.

On the scientific front, fire risks and impacts in the region are under-studied. Deeper research is needed on the weather conditions that fan fires, as well as the influences of ecology and management. Scientists need to know how the many factors behind large fires interact, including vegetation stress, extreme weather and human activities. And more studies are needed to inform fire management strategies in the region.

This year’s fire season in the Pantanal is exceptional. But the conditions that led to these blazes are becoming increasingly common as the area warms. In response, political, socio-economic and scientific approaches need to change. Researchers and governments need to come together to develop a comprehensive strategy for preventing and managing fires. Otherwise this great tropical wilderness will not bounce back.

Devastating impacts

With more than 84% of its territory conserved, the Pantanal is the largest remaining wetland area of natural vegetation in the world. It’s a UNESCO World Heritage Site. Indigenous, riverine and quilombo communities live there. Traditional farmers practice unique forms of sustainable agriculture, including grazing cattle on native pastures and moving animals to higher land when lowlands flood. Tourists flock to the region for its spectacular scenery, safaris and sport-fishing.

Each rainy season, from October to April, pulses of floods swell the Paraguay River to support ecosystems found nowhere else on Earth. Endangered jaguar, giant otter, marsh deer and hyacinth macaws roam wild. Thousands of birds pass through on their migrations1. It’s a haven for caimans, capybaras, monkeys, deer, coatis, tapirs, snakes and the jabiru stork (Jabiru mycteria) — the region’s symbol.

The fires have affected all aspects of life. COVID-19 has made things worse. PREVFOGO, the national centre for forest fire prevention and fighting, has struggled to hire and train firefighters. Many fires broke out in remote regions, even underground, that were hard to reach. Local firefighters in the Kadiwéu territory, for example, struggled almost alone to push back exceptionally fierce flames (see ‘Pantanal fire crisis’).

The total loss will take months to calculate. But the impacts are long lasting. Charcoal and ash contaminate rivers and promote harmful bacteria that poison drinking-water supplies and kill fish. Eroded soils are flushed downstream. Fire-sensitive plants struggle to produce seeds. Vast tracts of land will need to be assessed to understand whether they can be restored. Communities will have to be rebuilt.

Growing risk

What lies behind these fires? The Pantanal is no stranger to burning, even though it is a wetland2. For half the year it is dry and prone to catching alight, especially during drought. Sometimes lightning causes the spark. More often it is human-related — flashes from electrical cables, burning garbage and wood from cattle fences, use of fire to ward off bee attacks when collecting honey, and even car crashes and damaged agricultural machinery. Cattlemen burn the landscape to remove shrubs and stimulate the growth of native grasses, which are adapted to fire and sprout after pruning or scorching. Such fires regularly get out of control, especially in areas where there’s no system for managing them3.

The frequency and severity of fire outbreaks are worsening, as the climate warms and human impacts increase. Since 1980, average temperatures there have risen by 2 °C and humidity has fallen by 25%, according to the European Centre for Medium-range Weather Forecasts (ECMWF). This year saw the worst drought recorded in the Pantanal in 60 years (see go.nature.com/2jpdubc), induced by unusually warm waters in the North Atlantic4. The wet season saw 57% less rain than normal. By June, the Paraguay River was at half its usual level. This combination of hot, dry conditions pushed flammability thresholds to their highest since 1980. Such thresholds indicate the difficulty of controlling fires, a scale that is quantified using the averaged daily severity rating (DSR) index, which is derived from ECMWF data. Deforestation in Amazonia has also been linked to reduced rainfall in the Pantanal, although this is debated.

Environmental regulations are failing to keep up5. In July, Brazil’s government issued a 120-day ban on the use of fire in the Amazon and the Pantanal. It seems to have been widely ignored. The government has denied responsibility, blaming Indigenous peoples and traditional communities for starting fires, and criticized campaigns by the media and non-governmental organizations highlighting the exceptionality of the fire season.

Resources for environmental protection and climate actions have been slashed, especially in the past two years. The Ministry of the Environment’s US$630-million budget was cut by around 20% in 2020 and looks set to fall by a further 35% in 2021. Brazil is also failing to meet its commitment to reduce greenhouse-gas emissions under the Paris climate agreement6. Licensing requirements for dams, roads and mines have been weakened (Nature 572, 161–162; 2019). Last year, to promote agricultural and biofuel production, the government revoked the law that has prohibited new sugar-cane plantations in the Amazon and the Pantanal that has been in place since 20097. The decree was provisionally suspended by the Brazilian federal court in April, and is awaiting a final decision.