The Pantanal under Siege—On the Origin, Dynamics and Forecast of the Megadrought Severely Affecting the Largest Wetland in the World

Abstract

The Pantanal is the largest wetland of the world and one of the most important biodiversity hotspots in South America. An unprecedented ongoing megadrought is severely affecting its ecological functioning, flood pulse dynamics, and fire regime. Regarding this problematic, the present study generates reliable information about the following key issues: 1—Evolution and dynamics, 2—Origin and determinants, and 3—Forecast based on identified determinants and current trends. Results show that the evolution of the megadrought has been differentiable in both, space and time. As for its origin and determinants, Climate Change was ratified as one of the most important threats to the Pantanal, and to vast areas of South America, since a strong correlation was identified between megadrought’s dynamics and the occurrence of intense marine heatwaves at Northern Hemisphere oceanic waters, and more specifically, at the Northeast Pacific. Results also show that the megadrought is expected to continue at both the Pantanal and the surrounding Highlands, at least until December 2023. Thus, an intensification of fires risk, extending now to areas historically flooded or perhumid should be expected, concomitantly to a very negative impact on non-fire-resistant vegetation cover, as well as ecosystem functioning and biodiversity, perhaps even worse than those from 2020, widely covered by the international media.

Effects of Drought on Mortality in Macro Urban Areas of Brazil Between 2000 and 2019

“…These areas encompass more than 65 million people which corresponds to one-third of the country's population. These locations are distributed across the five main macro regions of Brazil, with Drought has been described as the disaster that affected the most population in Brazil between 2000 and 2020 (EM-DAT Atlas), with particular emphasis on the events which took place in the 2010-2016 period in Northeast Brazil (Marengo et al, 2018), in 2014-2015 drought in South-eastern Brazil (Coelho et al, 2016;Geirinhas et al, 2021), the drought events in 2005, 2010 and 2016 in Amazonia (Jimenez et al, 2018;Jiménez-Muñoz et al, 2016;Panisset et al, 2018), and in 2019-2020 in Pantanal (Libonati et al, 2020;Marengo et al, 2021;Thielen et al, 2020Thielen et al, , 2021. Recently, although outside our study period, the drought of 2021 affecting most South-eastern and Central-West has been reported to be facing one of the worst droughts ever recorded (Langenbrunner, 2021), showing the increasing trend toward drier periods.…”

Assessing the role of compound drought and heatwave events on unprecedented 2020 wildfires in the Pantanal

“…Among the 2020´s unprecedented climate conditions favoring fire activity in Oceania, Euro-Asia and North America, South America (SA) was not an exception [13]. Extreme dry conditions were reported in countries across centralsouth SA, reaching Argentina, Brazil, Bolivia and Paraguay [14][15][16]. Much of SA has been in drought since 2019, influenced by a warming trend in the sea surface temperature of Pacific and Atlantic Oceans [14][15][16][17].…”

“…Extreme dry conditions were reported in countries across centralsouth SA, reaching Argentina, Brazil, Bolivia and Paraguay [14][15][16]. Much of SA has been in drought since 2019, influenced by a warming trend in the sea surface temperature of Pacific and Atlantic Oceans [14][15][16][17].…”

Drought–heatwave nexus in Brazil and related impacts on health and fires: A comprehensive review

“…Several countries, including Brazil, Argentina, Peru, Paraguay, and Bolivia, have recorded a large number of HW events, with record‐breaking temperatures reaching up to 10°C above the 1981–2010 climatology. Those HWs occurred in the middle of an unprecedented drought that affected that region since 2018 linked to the warming trends in sea surface temperature of the Pacific and Atlantic Oceans 99,100,152 . On the other hand, the persistent atmospheric blocking conditions in the region fueled by a stationary Rossby wave train in the middle and upper atmosphere coming from the Indian Ocean region 151 were crucial for temperature escalation and large evaporation rates that resulted in pronounced soil moisture deficit during these HW episodes 38 .…”

“…When roughly 4 million hectares (1/3 of the biome) burned down in 2020, 103 including long stretches of wetlands and forest formations, 182 and around 17 million vertebrates were killed, 183 attention shifted to understanding why and how this fire‐sensitive biome was burning. The 2020 fire season in Pantanal was marked by anomalous meteorological conditions associated with unprecedented meteorological danger 103 and severe drought 99 . Libonati et al 33 .…”