Researchers determine the causes of the acute drought that affected the Pantanal

Publicado em 24 maio 2021

The intense drought suffered by the Pantanal in 2019-20, thought-about the worst within the final 50 years, was attributable to pure local weather circumstances just like these underlying the 2014-16 water disaster in São Paulo state. The Pantanal is likely one of the world’s largest wetlands. The Brazilian portion is positioned within the Heart-West area, primarily Mato Grosso do Sul state.

The 2019-20 excessive drought was studied by researchers affiliated with the Pure Catastrophe Surveillance and Early Warning Heart (CEMADEN), the Nationwide Area Analysis Institute (INPE) and São Paulo State College (UNESP) as a part of a undertaking supported by FAPESP below the aegis of its Analysis Program on International Local weather Change (RPGCC).

The outcomes of the examine are revealed within the journal Frontiers in Water.

“The current drought within the Pantanal was attributable to a meteorological phenomenon we name atmospheric blocking. A high-pressure space prevented the formation of rainclouds all through the central-western portion of South America. Temperatures had been very excessive and relative humidity very low,” José Marengo, a researcher at CEMADEN and principal investigator for the examine, informed Agência FAPESP.

“Lack of rain mixed with excessive temperatures and really low humidity led to a heightened danger of fireplace, which prolonged to agricultural areas in addition to pure elements of the biome.”

Deliberate burning of vegetation to clear land for cattle ranching contributed to the unfold of wildfires all through the area, and these had been more durable to manage owing to the lengthy interval of drought. “Fires brought about on one hand by hotter air and lack of rain within the Pantanal, and on the opposite by the burning of areas to clear the vegetation for cattle to graze, resulted in environmental catastrophe,” Marengo stated.

Sources of observational knowledge

To analyze the hydroclimatic causes of drought within the Pantanal, the researchers used an array of sources of observational hydrological knowledge (on the extent of the Paraguay River) in addition to knowledge on rainfall and hydroclimatic teleconnections (hyperlinks between hydrological occasions and atmospheric circulation patterns inflicting climate phenomena). In addition they used info on land use and distant sensing knowledge to characterize water stress and drought within the Pantanal.

Primarily based on an evaluation of all these datasets they had been in a position to present a transparent description of the interannual variability of rainfall, river streamflow, and drought-related elements, concluding that the drought was attributable to a fancy mixture of hydroclimatic teleconnections.

“The dearth of rain through the summer season in 2019 and 2020 within the Pantanal was on account of a lower within the circulation of heat humid air from the Amazon,” Marengo stated.

A part of the rain that falls on the Pantanal is introduced by winds blowing from the North Atlantic to the Amazon, and from there to the Pantanal in Brazil’s Heart-West area. The humidity coming down from the Amazon and chilly fronts arising from the South had been prevented from reaching the Pantanal by a high-pressure bubble. Because of this, plenty of hotter and drier air contributed to the shortage of rain through the summer season on the peak of the monsoon season, sometimes characterised by adjustments in atmospheric circulation and precipitation in tropical and subtropical coastal areas on account of uneven heating of land and sea.

The consequence was a protracted excessive drought all through the Pantanal, with severely opposed results on the biome. “This phenomenon is pure and occurred in an identical method in São Paulo through the 2014-16 drought,” Marengo stated.

Amplified influence

In response to Marengo, it isn’t but attainable to foresee whether or not the Pantanal will face extra extreme droughts within the years forward. The issue can solely be prevented if there’s the correct quantity of rain on the proper time. “It is no use getting rain now, in March, on the finish of the wet season, after which between December this 12 months and February 2022, for instance,” he stated. “This compromises the wet season and will increase the chance of extra wildfires within the Pantanal.”

Drought within the Pantanal can’t be blamed solely on international local weather change as a result of it’s a pure occasion and local weather change is a long-term course of. The current drought differed from these seen within the Nineteen Fifties and Sixties when the planet was cooler. “What’s taking place now could be that these pure droughts are struggling the results of local weather instability, and the results are worse as a result of again then there was loads much less human occupancy within the area. Its inhabitants is now extra susceptible to the influence of drought,” Marengo stated.

Fires triple in Brazil’s Pantanal wetlands in 2020

Extra info:

Jose A. Marengo et al, Excessive Drought within the Brazilian Pantanal in 2019–2020: Characterization, Causes, and Impacts, Frontiers in Water (2021). DOI: 10.3389/frwa.2021.639204


Researchers determine the causes of the acute drought that affected the Pantanal (2021, Could 24)

retrieved 24 Could 2021


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