The drought period in the Brazilian Amazon is more severe and the forest temperature increased by 2 degrees between 1985 and 2020, according to study led by scientists at the University of São Paulo. The analysis revised 35 years of deforestation, temperature and rainfall data on the biome, which allowed to measure the impact of deforestation and greenhouse gas emissions worldwide on the forest. Deforestation is responsible for 74.5% of rainfall reduction and 16.5% of increased biome temperature in the drought months.
The research separated the territory of the biome in 29 analysis blocks. These blocks, with a 300 -kilometer delimited area (km) by 300 km, were thought out as they allowed analyzes that considered climate behavior on a large scale, considering large rains and climate systems with kilometers scale. Its accuracy, however, was much closer: using the mapping developed for vegetation suppression monitoring through the Mapbiomas network, the researchers’ “vision” reached the impressive 30 meters. Crossing this information, it was possible to follow how, in the different quarters of the region, changes in vegetation cover over the decades had impact on precipitation and temperature.
In addition to understanding the process, they light another alert light: maintaining current devastation rhythms here and gases emission on the planet will increase climate extremes in the region, coming closer to what would be a stress point, with increasingly deep impacts on life balance in the region, already for 2035. Today, the average is 19% of coverage loss, but there are areas with a peak of 80% of deforested surface.
“The Amazon is a very complex biome that receives moisture from the ocean and has a very balanced dynamics about the hydrological cycle. It is already impacted, we need to start reversing this process and there is no margin for more stress factors in the biome or not,” explained Professor Marco Franco, from the USP Institute of Astronomy, the main author of the article, which was prominent in the journal Nature.
Researchers prefer not to talk about a non -return point to the forest, because the term has no consensus in the scientific community, but have no doubt that there is no safe margin to allow exploration in the region. Large developments, such as mines and plants, can further unbalance the surroundings, with the potential to affect extensive areas.
“This has already been felt in the production of the safrinha, which is a rare condition of our agribusiness, in relation to the world. In some areas of the biome it has had relevant falls. Drought is increasing, an average of 12 days every 10 years,” said Franco.
It is already felt from a relatively small threshold of suppression, with 10% vegetation loss in the analyzed areas. According to the data obtained, suppression rates between 10% and 40% of native vegetation lead to a more sudden drop of rainfall and accentuate the local increase in temperatures. From then on, the impact rate decreases, but it is becoming increasingly difficult to reforest.
Knowing this impact, warning participants, is more transparent the responsibility and possibility of cooperation between governments.
“We already knew that climate change occurred from other studies. Now we can measure this, which allows us to sit and talk to those responsible. Knowing our role, from Brazil, about deforestation, and talking to the rest of the world about the impact that greenhouse gas emissions have on the forest,” explained Professor Luiz Machado, who accompanied and coordinated the survey.
According to the results obtained, the rains had a reduction of about 21 millimeters (mm) in the dry season per year, with deforestation contributing to a decrease of 15.8 mm. The maximum temperature increased by 2 ° C, 16.5% attributed to the effect of forest loss and the remainder to global climate change. This weight varies. Areas of the Eastern Amazon, where vegetation cover is closer to the original, with suppression below 10%, suffer far less from drought. There the contribution to temperature increase is almost exclusive to industrial emission, external and linked to global northern countries, such as the United States and China. In southeastern areas of the biome, such as the region of Santarém, Pará, the impact of deforestation on increasing temperature is more balanced, besides the impact of droughts being much more relevant, Franco explained.
In the article, the researchers warn that if deforestation remains without control, the extrapolation of the results suggests an additional decline in total precipitation during the dry season and higher temperature rise. The group’s next challenge is to measure the possible impact, in different scenarios, on the forest, by the year 2100. One of the group’s contributions in addition to measurement and proof of this relationship between deforestation, precipitation and increased temperatures is the provision of parameters for other research groups, allowing biologists to use this data to understand impacts on more restricted species and territories, within the biome.
The Brazilian Amazon lost 14% of native vegetation between 1985 and 2023, according to Mapbiomas data, reaching an area of 553,000 km2, the equivalent to the territory of France. The pasture was the main cause in the period. Even with the fall in the last two years in relation to the deforested area, the fire and the advancement of agricultural areas continue to threaten the region.
