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Unusually dry conditions in the western Amazon could shrivel vegetation and create favorable conditions for fires early in the season, according to an international team of scientists monitoring the world’s largest rainforest.
The Department of San Martin in Peru, the Bolivian Amazon and the Pantanal Biome in Brazil are particularly vulnerable, according to scientists Kátia Fernandes and Douglas Morton in a seasonal forecast of fire risk in the Amazon. Fernandes and Douglas are part of SERVIR-Amazonia, a research program funded by NASA and the U.S. Agency for International Development (USAID).
The report forecasts an average to slightly-above-average fire season for the western Amazon, which covers Colombia, Ecuador, Peru, and parts of Bolivia and Brazil. The report also predicts below-average fire activity for most regions in the southern Amazon countries of Peru, Bolivia, and Brazil for the same months, with the exception of Santa Cruz, Bolivia, which could see higher fire activity. The report aims to aid countries in prioritizing areas for resource allocation.
This year’s lead-up to the southern Amazon fire season – which typically begins in June and peaks in September – has been drier compared to last year when intense fires nevertheless razed parts of the rainforest. (Near-average to above-average precipitation in May 2020 probably dampened fire season severity in some regions.)
“We have 20 years’ worth of data, and we understand how the Earth is working in some ways as a system,” says Morton. “We can use that in a productive way to predict conditions and help mobilize resources and attention to areas that might be more fire prone.”
The research nonprofit Amazon Conservation has already detected fires in the Brazilian Amazon this year, occurring more than a week earlier than last year and mostly in recently deforested areas. “The Brazilian government issued a ban on unauthorized outdoor fires on 27 June; thus we assume that most of the 160 major fires following that date have been illegal,” said the organization in its August report.
“Looking now and ahead at 2021, we predict a very high correlation between recently deforested areas (that is, cleared in 2020 and earlier in 2021) and major fires,” wrote Matt Finer, a scientist at Amazon Conservation, in an email. “As the dry season goes on and intensifies into August and September, there is a greater risk that these fires could get out of control and escape into the surrounding primary forest, creating actual Amazon forest fires.”
Last year’s cuttings could be this year’s fuel
More than 10,000 square kilometers of rainforest were cut down in 2019, and nearly the same amount was deforested in 2020 – the largest area in more than a decade. Preliminary numbers for 2021 suggest that the rate of deforestation is increasing. Logs, branches, and dried vegetation left by deforestation operations last year could be burned to clear lands this year, and scientists are concerned some of these fires could escape and spread into the Amazon’s primary forest areas.
Deforestation alerts from the Brazilian monitoring system and active fire data from NASA show that almost 5,000 square kilometers of area deforested since 2019 has not yet been burned. Most of the deforestation this year has taken place on unprotected lands, private properties and federal lands without a protected status, and many of them are near standing forests.
“We know that lots of land was cleared last year and not burned,” says Paulo Brando, an expert on tropical ecology who collaborates with the Amazon Environmental Research Institute (IPAM Amazônia). “So there’s this pile of unburned stuff, and it’s just a matter of when we’re going to create this huge bonfire, one of the biggest bonfires on the planet.”
The complexity of the seasons
Although it is mostly covered by dense, moist tropical forests, the Amazon’s 6.7 million square kilometers are a vast mosaic of ecosystems with different temperature and precipitation regimes: rainforests, seasonal forests, deciduous forests, flooded forests and savannas. When scientists talk about the fire season in the Amazon, they often aren’t referring to the entire biome.
Forest fires in the Amazon typically happen after an area has been deforested. Forests are usually cut in the wet season and burned during the dry season. In the northern Amazon, the dry season is from November to May, and in the southern Amazon, from May to November.
The intensity of the wet and dry seasons varies as well. Like many tropical regions, the Amazon is vulnerable to changes in rainfall from phenomena such as El Niño and La Niña – significant increases or decreases in sea surface temperatures in the central and equatorial Pacific that happen at irregular intervals and range between two and seven years.
The Amazon is also vulnerable to sea surface temperature changes in the tropical Atlantic Ocean, the region that gives rise to hurricanes that hit the U.S. The sea surface temperature changes in the Atlantic can actually shift rainfall in hurricanes away from South America and the Amazon region. “So, some of the worst droughts in the Amazon are actually connected to warm Atlantic sea surface temperatures rather than El Niño years,” says Morton.
SERVIR Amazonia’s western Amazon forecast was derived from a fire forecast model using sea surface temperature (SST) data in the Atlantic. For the southern Amazon, researchers used SST data from the tropical Pacific and Atlantic oceans, along with 20 years of satellite fire detections from the NASA Terra satellite.
This year is a La Niña year, however. “It turns out that the southern portion of South America is more vulnerable to rainfall or to drought during La Niña conditions,” says Morton. “And so part of the current drought across the Cerrado and Pantanal biomes, and to a small extent the southern Amazon region, we attribute to La Niña patterns that tend to lead to lower rainfall in those regions.”
Eyes on the Amazon
Because it is the largest rainforest in the world, the Amazon has been valued as a significant carbon sink, able to absorb excess carbon dioxide in the atmosphere, aiding the mitigation of global warming. But because of recent forest fires, studies suggest that parts of the Amazon now release more carbon than they store.
Marcia Macedo, an associate scientist at the Woodwell Climate Research Center, says many groups are monitoring the fire situation in the Amazon and working on solutions. “But it’s a little bit of a moving target,” she says. “Obviously, there is the pandemic, the change in government, the change in deforestation rates, and also climate change is altering fire regimes. You have areas that never used to burn that are burning, and they’re burning differently than they used to.”
The Amazon currently has an unprecedented number of satellite monitoring programs analyzing decades of data and now seeing real-time fire events.
“We know what is happening. We have never had so many satellites, so many platforms, tools or algorithms that can watch the Amazon from space,” says Brando. Yet he laments that, nevertheless, the Amazon is being lost in plain sight.
“We haven’t managed to change the political will with the amazing science being done in ways that would be unthinkable a couple of decades, even years ago,” he says.
A new study by Amazon Conservation suggests that Indigenous territories and protected area designations are some of the best hopes for long-term conservation of critical remaining forests in the Amazon.
Macedo has also observed this. “Indigenous lands, for sure, do a great job, and they do a little better than protected areas because they have people on the ground that are managing them and advocate for conservation,” she says. “But these lands are not immune; we do see some signs of forest degradation.
“Everybody’s just trying to figure out what’s the formula for dealing with the new reality in some of these places.”