Tunnels dug by semi-fossorial mammals of the South American Cenzoic megafauna are known as paleoburrows and are generally described from isolated records or very restricted regions. A particularly favorable set of conditions allowed the systematic mapping of paleoburrows over more than a decade in the Porto Alegre metropolitan area (Rio Grande do Sul state, Brazil), covering more than 10,000 km2. Through digital prospecting, media strategies and fieldwork, more than 400 paleoburrows were found in this region, usually in large-scale anthropogenic excavations. The structures may consist of a single one or several tunnels, reaching up to two or three dozen. Burrows can be opened or filled with sediments to variable extent. More than 80% of the tunnels are completely filled with sediment, thus classified as crotovines. Their widths range between 0.5 and 3.0 m and their heights are between 0.5 and 2.0 m. Tunnels with a diameter of 1.4 m, with original estimated lengths of more than 50 m, are frequent. Excavation traces on burrow walls and roofs are common, but fossils have not been found. In very flat areas like floodplains or areas with very uneven relief (mountainous), paleoburrows are rare to absent. The largest amount of tunnels were found in regions of hilly and relatively stable relief, dug in different lithotypes except unconsolidated sediments or unaltered magmatic or metamorphic rocks. It is possible that each hill may have several paleoburrows, isolated or in groups, around its base. Thus, the region can be considered the one with the highest known density of paleoburrows of this type in the world so far.

Global climate change is expected to increasingly affect climate-sensitive sectors of society, such as the economy and environment, with significant impacts on water, energy, agriculture and fisheries. This is the case in South America, whose economy is highly dependent on the agricultural sector. Here, we analyzed the sensitivity of South American climate to positive extremes of Antarctic sea ice (ASI) extent and volume at continental and regional scales. Sensitivity ensemble experiments were conducted with the GFDL-CM2.1 model and compared with the ERA-Interim reanalysis dataset. The results have shown significant impacts on the seasonal regime of precipitation, air temperature and humidity in South America, such as a gradual establishment of the South Atlantic Convergence Zone, the formation of the Upper Tropospheric Cyclonic Vortex, the strengthening of Bolivian High and the presence of a low level cyclonic circulation anomaly over the South Atlantic Subtropical High region which contributed, for instance, to increased precipitation over the Southeastern Brazil. A northward shift of the Intertropical Convergence Zone was initially also a response pattern to the increased ASI. Moreover, the greatest variance of the climatic signal generated from the disturbances applied on the high southern latitudes has occurred in the interseasonal timescale (110-120 days), especially over the Brazilian Amazon and the Southeastern Brazil regions.

The variability of Antarctic sea ice (ASI) has great potential to affect atmospheric circulation, with impacts that can extend from the surface to the middle and high levels of troposphere. The present study has evaluated the response of South Atlantic tropospheric circulation to increased coverage in area and volume of ASI. Monthly data of air temperature, zonal and meridional wind and mean sea level pressure were obtained from two ensemble simulations performed with the GDFL/CM2.1 model, covering the period from July 2020 to June 2030. In general, the response of South Atlantic tropospheric circulation to increased ASI showed that the climatic signal extended up from the surface to the high levels, propagating as a South Pole-Tropics teleconnection. The results show a general cooling of the southern troposphere, which for instance lead to the strengthening and northward shift of the polar jet and the southward shift of the subtropical jet and to an inversion from the positive to negative phase of the Southern Annular Mode. This study has great relevance for understanding the global climate changes in short term, by assessing the sensitivity of South Atlantic tropospheric circulation to extreme variations in ASI.

This study analyzed the influence of strong and moderate El Niño-Southern Oscillation (ENSO) events on the seasonal and interannual variabilities of the sea surface temperature (SST) in the Western Equatorial Atlantic (WEA) Ocean and how the precipitation over the state of Maranhão, in Brazil, responds to the zonal teleconnection. To evaluate the ENSO magnitude and phase in the four Niño regions (1+2, 3, 3.4, and 4), the SODA 3.3.1 oceanic reanalysis database for the period from 1980 to 2015 was used. Our results showed that the La Niña phase with moderate magnitude was the most predominant among the 70 events analyzed, with Niño 3.4 presenting the highest number (20) of ENSO events (both positive and negative phases). At lag = 0, we found that significant negative correlations prevailed between the WEA SST anomalies and ENSO index, with the region of Niño 3.4 showing the most significant correlations (r = −0.25). The whole events of El Niño and La Niña were, respectively, accompanied by a cooling and a heating of up to −0.6°C or +0.8°C in the WEA Ocean. The WEA SST anomalies during El Niño and La Niña events have, respectively, reduced and increased the precipitation in Maranhão around ± 100 mm in a quarter. Strong El Niño events influence a greater precipitation deficit in Maranhão than moderate El Niño events. Moderate La Niña events have more pronounced influence on the precipitation over Maranhão than strong La Niña events do, especially on the negative anomalies. Our results showed that the central, northern, and eastern tip sectors of the state are the most affected by this zonal teleconnection. We concluded that ENSO’s significant influences on the WEA SST seasonal variability, added to the performance of the Atlantic Meridional Mode (Soares, 2019 Soares, L. A. M. 2019. Influência de teleconexão Pacífico–Atlântico e de modos locais na variabilidade da temperatura da superfície do mar do Atlântico Equatorial Ocidental e impactos sobre a precipitação no estado do Maranhão (mathesis). Universidade Federal do Maranhão, São Luís. ), determine the quality of the rainy season (March–April–May) in the state of Maranhão.

Brazil harbors the second largest expanse of mangroves in the world, trailing only behind Indonesia. In a regional context, the state of Maranhão stands out, encompassing approximately 36% of Brazil’s total mangrove area, including a portion located on the eastern coast in the Lençóis Maranhenses. This study played a crucial role in identifying the areas of gain, loss, and stability in the mangroves surrounding the Lençóis Maranhenses National Park over a historical period spanning from 1985 to 2019. The study provided detailed maps depicting spatial changes, such as migration and attenuation that occurred in the mangroves due to the influence of aeolian dunes and wind patterns in the region. This long-term analysis, the first of its kind to examine the annual expansion of forest loss in the remaining mangroves around the Lençóis Maranhenses in recent decades, revealed a reduction in the central mangrove areas between 1985 and 2019. This decline can be attributed not only to intense tourist activity and climate change but also to the movement and invasion of sand dunes in certain areas, as observed near the villages of Caburé and Paulino Neves (Pequenos Lençóis) in December 2022. Wind plays a fundamental role as a transformative agent in the local landscape. Through the analysis of wind roses using ERA5 reanalysis data and meteorological stations from the Aeronautics (São Luís and Parnaíba), it was possible to identify and characterize the prevalence of northeast trade winds in the Lençóis Maranhenses region during the years 1985 to 2019, with average speeds ranging from 6 to 8 m/s. The advancement of dunes onto the mangroves surrounding the Lençóis Maranhenses results in burial, reduction, and even migration of mangrove patches. Additionally, over the years, population growth and increasing tourism pressure along the banks of the Preguiças River have drawn attention to the need to implement control and conservation measures in the mangroves to prevent further disturbances in this environment.