Manaus, capital of the state of Amazonas, and the entire eastern region of the state are suffering the worst drought in the last 103 years. This is the evaluation made by the scientist Carlos Nobre.
According to Nobre, who works for the National Institute of Space Research (Inpe), the rainfall indices in the eastern region are the lowest in the last 60 years.
"When it comes to the Rio Negro, in Manaus, this drought has no parallel in the last 103 years. That is, since 1902, when the level of the Rio Negro began to be measured. In the eastern part of the region, this is the worst drought in the last 50 or 60 years," he estimates.
Nobre explains that the drought is caused by three factors: the warming of the Atlantic Ocean, reduction in arboreal transpiration, and the smoke emitted by burnings.
"The chief reason is the warming of the Northern Tropical Ocean, which is up to two degrees warmer than average. The water induces considerable rainfall in the region, as well as an upward movement – common in places where it rains a lot.
"And everything that rises must fall. This air, which descends upon the Amazon region, interferes with cloud formation. This explains the great extension, gravity, and duration of this quite atypical drought," he explains.
The other two factors are less important in determining the intensity of the drought, according to the scientist. He concurs that prolonged droughts cause plants to transpire less, curtailing the water cycle. He also observes that deforestation exists in 17% of the Brazilian Amazon "in a widely distributed manner."
Nobre points out, however, that there are studies that show that smoke from the burnings "can also interfere with cloud formation during the dry season."