Amazonian capitals are among the least vegetated cities in Brazil. An exclusive analysis by InfoAmazonia shows temperature differences between tree-covered and treeless areas in the two Amazonian capitals.

The Amazon biome is home to an estimated 390 billion trees. But in cities—where 70% of the region’s population lives—shade is the exception, not the rule. According to data from Brazil’s Institute of Geography and Statistics (IBGE), Amazonian municipalities are among the least vegetated in the country, with Belém and Manaus ranking among the ten worst state capitals.

An exclusive analysis by InfoAmazonia identified the widespread presence in both capitals of urban heat islands—areas where temperatures are significantly higher than in nearby rural and forest zones—with dozens of points in each city ing temperatures up to 10°C hotter than the surrounding forest.

To arrive at these findings, our analysis used Landsat 8 satellite data, accessed through the U.S. Geological Survey (USGS), for two capitals of Brazil’s Legal Amazon: Manaus (AM) and Belém (PA). With this data, InfoAmazonia mapped the cities’ vegetation and created heat maps comparing various urban points to forested and rural zones just outside of the cities. 

Overlaying our heat and vegetation maps showed that trees have a significant impact on city temperatures in the Amazon. Vegetated areas in Manaus and Belém were often several degrees cooler than neighboring zones dominated by concrete.

In Manaus, according to InfoAmazonia’s analysis, 41.7% of the surface area is covered with vegetation; in Belém, the figure is 39.6%. Our reporting shows that Belém—set to host COP30 this year—had an average temperature 2.6°C higher than the surrounding forest, which InfoAmazonia represented using the nearby Combu Archipelago Environmental Protection Area. Additionally, in 17.1% of Belém’s surface area, temperatures were at least 5°C higher than in the adjacent protected area.

In Manaus, residents live with temperatures averaging 3°C higher than the nearby forest, represented in our analysis with the nearby Adolpho Ducke Forest Reserve. In 16% of the city, the difference is at least 5°C. More than 85% of Manaus’s population lives in neighborhoods that, at the time of the satellite capture, had surface temperatures more than 3°C hotter than the preserved area outside of the city.

Heat islands form due to a combination of characteristics common to urban environments. Surfaces of concrete and asphalt absorb and retain heat throughout the day, releasing it for hours even after sunset. Heavy traffic and air conditioning units also emit heat while narrow streets and tall buildings limit air circulation, preventing hot air from escaping. The air pollution generated by cities intensifies the problem, creating a localized greenhouse effect.

“The most noticeable consequence of the lack of trees in an urban center is high temperatures,” said Yêda Arruda, director of the Árvores do Asfalto (Trees of the Asphalt) research group at the Federal University of Amazonas (UFAM), in Manaus.

Trees have a tremendous cooling effect on the area around them. In addition to providing shade, trees purify the air and cool the environment through evapotranspiration—the process by which water is released through leaves. As a result, cities with more trees can mitigate or even eliminate heat islands, meanwhile those with little vegetation suffer from intense heat pockets, a problem worsened by global warming.

“Tree planting is not treated as a priority” in Belém, said Rafael Salomão, an urban vegetation researcher at the Emílio Goeldi Museum in Belém. According to an analysis by CarbonPlan and The Washington Post, Belém had fewer than 50 days of extreme heat in 2000 but is projected to have 222 such days in 2050—the largest increase among major cities worldwide.

Worse in the Periphery

Raimundo Rodrigo do Vales, a fruit vendor in Belém’s Cidade Velha neighborhood, said “the Amazon should be a model” for urban tree cover. In the neighborhood where he works, vegetation covers only 19.9% of the area, according to InfoAmazonia’s analysis.

Vales said the city feels hotter in recent years, which he sees directly in the condition of his fruits: “Bananas spoil quickly in very elevated temperatures,” he said.

The distribution of trees in Amazonian cities is unequal: peripheral neighborhoods tend to have fewer trees and are also more vulnerable to the effects of heat islands. “In the periphery, there are hardly any [trees]. Only in the city center. Belém is known as the city of mango trees. But it’s only in the center,” do Vales said.

Residents of poorer areas often can’t afford to build homes with cooler materials like ceramic, nor install air conditioning or pay for the electricity needed to run fans.

Sacramenta, a peripheral area, is Belém’s third-hottest neighborhood, with surface temperatures about 5.5°C higher than those on Combu Island, the nearby nature reserve, InfoAmazonia found. It also has only 17.5% vegetation cover—the eighth-lowest of Belém’s neighborhoods, according to the analysis.

One particularly scorching spot in the neighborhood is on Pedro Álvares Cabral Avenue, where a large, air-conditioned shopping mall faces a paved parking lot and a gas station, without a tree in sight. Satellite data show that surface temperature there reaches 8.6°C higher than the forest around Belém.

“In the center [of Belém] there are [trees], but not here in the periphery,” said Jefferson Pereira, a lottery ticket seller in Sacramenta who has worked outside the mall’s parking lot for five years. He said the heat gets worse every year. His only assists are an umbrella, a large water bottle, and an occasional breeze that sometimes blows down the avenue during the rainy season. In the Amazonian summer, the heat is even more intense, he said.

Ana Luíza de Araújo, part of the Urban River Defenders group—which works on tree planting in Belém’s Terra Firme neighborhood, the city’s fourth hottest—explains that disorganized growth in the periphery has contributed to the city’s lack of vegetation. “In geography, we call this a floristic desert: many people and few trees,” she said.

“When people build their homes, they often cut down trees to make space,” she said. “But this is also a result of a lack of public planning… Infrastructure projects in the periphery typically follow the logic of gray infrastructure based on concrete and asphalt.” 

Infrastructure projects in the periphery typically follow the logic of gray infrastructure based on concrete and asphalt.

Ana Luíza de Araújo, part of the Urban River Defenders group

Belém’s Secretary of the Environment (SEMMA) said in a statement to InfoAmazonia that one of the biggest challenges to planting trees in the periphery “is finding planting locations, as some neighborhoods were haphazardly settled, leaving little room for greenery.”

In Manaus, the situation is similar, Arruda said. When the city’s Free Trade Zone was created in the 1960s, masses of people moved to the city, triggering disorganized urban sprawl—a process she says still hasn’t stopped. “This type of settlement pattern also causes a major problem: there’s nowhere to plant,” she said.

But even in neighborhoods that are not a product of informal settlement, Amazonian cities still suffer from a desperate lack of trees. 

The Dom Pedro neighborhood in Manaus, planned as a housing development in the 1970s, now has barely any trees despite its straight and organized streets. Not coincidentally, according to InfoAmazonia’s analysis, it is also the hottest neighborhood in the city, with an average surface temperature 5.4°C hotter than the forest surrounding Manaus at the time of the satellite’s measurement.

The Parque 10 de Novembro neighborhood, a middle-class area, is the third-hottest in Manaus, averaging 4.9°C hotter than the Adolpho Ducke reserve. A deep red spot on InfoAmazonia’s heat map centers around Parque 10’s huge Carrefour supermarket complex in front of a big parking lot and next to Mário Ypiranga Avenue, one of the city’s busiest arteries. Satellite data showed a surface temperature here as high as 35.9°C—9.5°C hotter than the Adolpho Ducke Reserve.

“Even being used to it, it’s difficult,” said Luan Albuquerque da Silva, who works at a snack stand across from the Carrefour parking lot, about the heat of Manaus. As he spoke, he wiped sweat from his forehead with a napkin. “People end up ing out,” he added.

The Green Solution

Other parts of the Parque 10 neighborhood benefit from the cooling effect of trees. The Mindú Stream, running through the neighborhood, is bordered by a rare green corridor. There, the surface temperature drops to as low as 28.2°C. For comparison, just a few blocks away, on the treeless Silva Alvarenga Road, temperatures reach 33.8°C, which is 7.4°C hotter than the Adolpho Ducke Reserve.

Similarly, in Belém, our data show that urban heat islands can be mitigated and even eradicated with trees. In the Guamá neighborhood, the city’s most populous neighborhood, the Santa Izabel Cemetery is an island of trees in a sea of ​​concrete. Within the cemetery’s gates, the surface temperature is only 2°C above the temperature of the forest around the city. But just a few blocks away, the trees disappear and the urban heat island effect rises to 6°C.

“We need to understand that the urban environment is a degraded environment,” explained Arruda, the researcher at UFAM. “There are problems with the soil, and there are high temperatures both on the ground and due to the lack of shade and protection for the plants.”

Salomão, the researcher at the Emílio Goeldi Museum, said that in an urban environment, planting trees requires the consideration of “many parameters.”

“If the road is narrow, there are limitations. If there is an electrical grid, that is another. Or even the underground network of cables and pipes… all of this interferes,” he explained.

However, according to Salomão, the Amazon is home to more than 16,000 different species of trees — which means that there are species appropriate for practically every situation. “We need to think about planting trees specifically for each location, and not, for example, go around planting mango trees on every street,” he said. According to Salomão’s research, only 4.1% of the trees in Belém are native species of the Amazon.

In its statement, Belém’s Secretary of the Environment said that, at the beginning of this year, the city recuperated its tree nursery, an area outside the city intended for the production of native seedlings to be used for urban tree planting.

Recently, Belém’s tree planting policy went viral after the city installed “artificial trees” in a new park being built for COP30, in the Reduto neighborhood — which has the least amount of vegetation coverage of any neighborhood in the city, according to InfoAmazonia’s analysis. The structures, now renamed by the city as “hanging gardens,” are metal, in the shape of trees, and several potted plants in place of the canopy. The measure was widely ridiculed on social media, with many pointing out the irony of the host city, in the middle of the Amazon, of an international climate conference, opting for replicas of trees instead of natural ones.

The city claimed that there was not enough space for roots or soil in the area to real trees. But Salomão said that’s not necessarily an excuse. “If you have 16,000 species, you have species for everything,” he said. “Now, if you still can’t successfully plant, you can think about placing large pots.”

But Belém is also planting real trees, both in the park in Reduto and in other areas of the city. Earlier this year, the city government announced a plan to plant 17,000 seedlings of native species throughout the city, with the goal of making Belém the “greenest capital in Brazil.”

The city’s Secretary of the Environment told InfoAmazonia that, so far, it has planted 7,000 seedlings as part of the initiative. Meanwhile, Manaus previously announced that it will plant 15,000 seedlings throughout the city in 2025. Manaus’ Secretary of the Environment, however, did not respond to a list of questions sent by InfoAmazonia.

Urban tree planting advocates say they have heard promises like these before. “Government agencies, NGOs, tree sympathizers, and politicians in election campaigns all start planting [trees]. But they don’t monitor [the growth]. It’s no use. It’s a waste of money,” Arruda said, adding that trees in urban environments often die quickly without constant .

Instead of just planting more seedlings, experts want cities to carefully select which species of trees to plant and invest in helping trees grow even after they have been planted. 

All of this is expensive, but given the enormous impact on the urban climate, it’s worth it, said Salomão: “the return is much greater.”