Interactive effects of environmental variability and human impacts on the long-term dynamics of an Amazonian floodplain lake and a South Atlantic coastal lagoon

AbstractSubtropical ocean gyres play a key role in modulating the global climate system redistributing energy between low and high latitudes. A poleward displacement of the subtropical gyres has been observed over the last decades, but the lack of long-term monitoring data hinders an in-depth understanding of their dynamics. Paleoceanographic records offer the opportunity to identify meridional changes in the subtropical gyres and investigate their consequences to the climate system. Here we use the abundance of planktonic foraminiferal species Globorotalia truncatulinodes from a sediment core collected at the northernmost boundary of the South Atlantic Subtropical Gyre (SASG) together with a previously published record of the same species from the southernmost boundary of the SASG to reconstruct meridional fluctuations of the SASG over last ca. 70 kyr. Our findings indicate southward displacements of the SASG during Heinrich Stadials (HS) 6-4 and HS1, and a contraction of the SASG during HS3 and HS2. During HS6-4 and HS1, the SASG southward displacements likely boosted the transfer of heat to the Southern Ocean, ultimately strengthening deep-water upwelling and CO2 release to the atmosphere. We hypothesize that the ongoing SASG poleward displacement may further increase oceanic CO2 release.

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Extreme rainfall deficits were not the cause of recurring colonial era famines of southern Indian semi-arid regions

Scientific Reports ◽

10.1038/s41598-021-96826-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ranjini Ray ◽

Atreyee Bhattacharya ◽

Gaurav Arora ◽

Kushank Bajaj ◽

Keyle Horton ◽

...

Keyword(s):

Arid Regions ◽

Human Impacts ◽

Rainfall Variability ◽

Extreme Rainfall ◽

Southern India ◽

Colonial Era ◽

Regional Rainfall ◽

Semi Arid ◽

Rainfall Deficits

AbstractUsing information contained in the eighteenth to twentieth century British administrative documents, preserved in the National Archives of India (NAI), we present a 218-year (1729–1947 AD) record of socioeconomic disruptions and human impacts (famines) associated with ‘rain failures’ that affected the semi-arid regions (SARs) of southern India. By mapping the southern Indian famine record onto long-term spatiotemporal measures of regional rainfall variability, we demonstrate that the SARs of southern India repeatedly experienced famines when annual rainfall reduced by ~ one standard deviation (1 SD), or more, from long-term averages. In other words, ‘rain failures’ listed in the colonial documents as causes of extreme socioeconomic disruptions, food shortages and human distress (famines) in the southern Indian SARs were fluctuations in precipitation well within the normal range of regional rainfall variability and not extreme rainfall deficits (≥ 3 SD). Our study demonstrates that extreme climate events were not necessary conditions for extreme socioeconomic disruptions and human impacts rendered by the colonial era famines in peninsular India. Based on our findings, we suggest that climate change risk assessement should consider the potential impacts of more frequent low-level anomalies (e.g. 1 SD) in drought prone semi-arid regions.

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Estimation of Water Storage Changes in Small Endorheic Lakes in Northern Kazakhstan; The Effect of Climate Change and Anthropogenic Influences

10.20944/preprints201712.0045.v1 ◽

2017 ◽

Author(s):

Vadim Yapiyev ◽

Kanat Samarkhanov ◽

Dauren Zhumabayev ◽

Nazym Tulegenova ◽

Saltanat Jumassultanova ◽

...

Keyword(s):

Climate Change ◽

Remote Sensing ◽

Water Resources ◽

Water Balance ◽

Climate Model ◽

Human Impacts ◽

Water Storage ◽

Minor Importance ◽

Climatic Data

Both climate change and anthropogenic activities contribute to the deterioration of terrestrial water resources and ecosystems worldwide. Central Asian endorheic basins are among the most affected regions through both climate and human impacts. Here, we used a digital elevation model, digitized bathymetry maps and Landsat images to estimate the areal water cover extent and volumetric storage changes in small terminal lakes in Burabay National Nature Park (BNNP), located in Northern Central Asia (CA), for the period of 1986 to 2016. Based on the analysis of long-term climatic data from meteorological stations, short-term hydrometeorological network observations, gridded climate datasets (CRU) and global atmospheric reanalysis (ERA Interim), we have evaluated the impacts of historical climatic conditions on the water balance of BNNP lake catchments. We also discuss the future based on regional climate model projections. We attribute the overall decline of BNNP lakes to long-term deficit of water balance with lake evaporation loss exceeding precipitation inputs. Direct anthropogenic water abstraction has a minor importance in water balance. However, the changes in watersheds caused by the expansion of human settlements and roads disrupting water drainage may play a more significant role in lake water storage decline. More precise water resources assessment at the local scale will be facilitated by further development of freely available higher spatial resolution remote sensing products. In addition, the results of this work can be used for the development of lake/reservoir evaporation models driven by remote sensing and atmospheric reanalysis data without the direct use of ground observations.

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The role of the Microbial Conveyor Belt on Earth´s system resilience

10.5194/egusphere-egu21-1832 ◽

2021 ◽

Author(s):

Mireia Mestre ◽

Juan Höfer

Keyword(s):

Human Impacts ◽

Conveyor Belt ◽

Earth System ◽

Planetary Scale ◽

Microbial Biogeography ◽

The Earth ◽

System Resilience ◽

Global Biogeochemical Cycles

<p>Despite being major players on the global biogeochemical cycles, microorganisms are generally not included in holistic views of Earth&#8217;s system. The Microbial Conveyor Belt is a conceptual framework that represents a recurrent and cyclical flux of microorganisms across the globe, connecting distant ecosystems and Earth compartments. This long-range dispersion of microorganisms directly influences the microbial biogeography, the global cycling of inorganic and organic matter, and thus the Earth system&#8217;s functioning and long-term resilience. Planetary-scale human impacts disrupting the natural flux of microorganisms pose a major threat to the Microbial Conveyor Belt, thus compromising microbial ecosystem services. Perturbations that modify the natural dispersion of microorganisms are, for example, the modification of the intensity/direction of air fluxes and ocean currents due to climate change, the vanishing of certain dispersion vectors (e.g., species extinction or drying rivers) or the introduction of new ones (e.g., microplastics, wildfires). Transdisciplinary approaches are needed to disentangle the Microbial Conveyor Belt, its major threats and their consequences for Earth&#180;s system resilience.</p>

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Regional Manifestations of Late Quaternary Climate Change and Archaeological Site Burial Along the South Atlantic Coastal Plain

Early Human Life on the Southeastern Coastal Plain ◽

10.5744/florida/9781683400349.003.0010 ◽

2018 ◽

pp. 193-235 ◽

Cited By ~ 1

Author(s):

Christopher R. Moore ◽

Mark J. Brooks ◽

I. Randolph Daniel ◽

Andrew H. Ivester ◽

James K. Feathers ◽

...

Keyword(s):

Coastal Plain ◽

Late Quaternary ◽

Archaeological Site ◽

South Atlantic ◽

Atlantic Coastal Plain ◽

Luminescence Dating ◽

The South ◽

Ams Radiocarbon Dating ◽

Paleoclimate Records ◽

Atlantic Coastal

Archaeological site investigations on the South Atlantic Coastal Plain have revealed stratified cultural remains in sand deposits of mixed aeolian and fluvial origins, aeolian sand sheets and dunes, alluvial terraces, and Carolina Bay rims. These sites are typically shallow but have yielded discernible archaeostratigraphy within sand dominated deposits by using luminescence dating (OSL), AMS radiocarbon dating, and close interval sediment sampling. Periods of site burial are linked to regional and global paleoclimate records, including Bond events, and provide broader reconstructions for human ecology and periods of site burial.

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Cross-Shelf Exchange Associated With the Gulf Stream in the South Atlantic Bight: Direct Observations Using an Autonomous Underwater Glider

Marine Technology Society Journal ◽

10.4031/mtsj.52.3.5 ◽

2018 ◽

Vol 52 (3) ◽

pp. 19-27 ◽

Cited By ~ 1

Author(s):

Ruoying He ◽

Austin C. Todd ◽

Chad Lembke ◽

Todd Kellison ◽

Chris Taylor ◽

...

Keyword(s):

Gulf Stream ◽

Moving Boundary ◽

South Atlantic ◽

South Atlantic Bight ◽

Underwater Glider ◽

The South ◽

Underwater Gliders ◽

Direct Observations ◽

Autonomous Underwater Glider

AbstractAn autonomous underwater glider was deployed in March 2014 to sample the Gulf Stream and its adjacent shelf waters in the South Atlantic Bight, providing a new look at cross-shelf exchange associated with Gulf Stream dynamics. Observations collected over 4 weeks reveal significant cross-shelf exchange (up to 0.5 Sv) at the shoreward edge of the Gulf Stream, which was 2 orders of magnitude larger than estimates from long-term mean hydrographic conditions. Gulf Stream frontal eddies may have contributed to some of the largest fluxes of heat (0.5°C Sv) and salt (0.03 Sv g/kg) onto the shelf. We estimate that the largest upwelling event during the mission could have brought nitrate concentrations over 20 μM to within 125 m of the surface. This study demonstrates clear capabilities of autonomous underwater gliders for sampling in and near fast moving boundary currents to obtain unique and critical in situ observations effectively.

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The evolution of biogeochemistry: revisited

Biogeochemistry ◽

10.1007/s10533-020-00708-0 ◽

2020 ◽

Author(s):

Thomas S. Bianchi

Keyword(s):

20Th Century ◽

Atmospheric Chemistry ◽

Large Scale ◽

Agricultural Soils ◽

Human Impacts ◽

Organic Geochemistry ◽

Evolutionary Genetics ◽

Satellite Monitoring ◽

Analytical Approaches

AbstractThe evolution of biogeochemistry, retraces the important historical steps in part, covered by Gorham (Biogeochemistry 13:199–239, 1991) in the 18–19th centuries—with new emergent linkages and trends in 20–21st centuries. In the post-phlogiston period, key synthetic connections are made between weathering, atmospheric chemistry, carbon cycling, and climate change. Early work in the 19th century, focused on weathering and the importance of organisms in the exchange of carbon dioxide between the rocks and the atmosphere, provided foundations for new analytical approaches. The role microbes in connecting abiotic and biotic processes begins to emerge, based largely on the existing knowledge of stoichiometry in agricultural soils and plants. This in part, leads to the founding of ecology and its linkages with evolution and biogeography. Verandsky boldly emerges in the 20th century, with his concepts of a biosphere and a noosphere, as concerns begin to arise about human impacts on nature. The development of organic geochemistry as a discipline, allowed for new roots to develop in the evolution of biogeochemistry through linkages between short and long-term carbon cycles. In the 20th century, a new interesting stoichiometry emerges in biogeochemistry—as related to the Green Revolution, human population growth, and eutrophication problems. The advent of long-term and large-scale experiments help to constrain the complexity of non-linearity and regional differences in fluxes and rates in biogeochemical work. A new age begins in the 21st century whereby molecular approaches (e.g. omics) combined with large-scale satellite, monitoring, survey, observatory approaches are combined in the development of Earth System models. These new connections with ecological/evolutionary genetics are one of the more dramatic and important aspects of biogeochemistry in modern times.

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Long-term hydrological changes after various river regulation measures: are we responsible for flow extremes?

Hydrology Research ◽

10.2166/nh.2019.095 ◽

2019 ◽

Vol 50 (2) ◽

pp. 417-430 ◽

Cited By ~ 1

Author(s):

Tímea Kiss ◽

Károly Fiala ◽

György Sipos ◽

Gábor Szatmári

Keyword(s):

Human Impacts ◽

Morphological Changes ◽

River Regulation ◽

Mass Movements ◽

Channel Adjustment ◽

Flood Level ◽

Flow Changes ◽

Tisza River ◽

Natural Channel

Abstract Engineering works have affected the morphology of rivers (e.g., by cut-offs, artificial levees, revetments, and reservoir and dam constructions). These human impacts also have hydrological impacts, as they alter the natural channel geometry, affect the carrying capacity of the channel and confine the floodplains. The goals of the present paper are to analyse flow changes for the Tisza River (in Hungary) with its highly regulated channel using a long (141 y) daily hydrologic dataset and to evaluate the engineering works from the point of hydrological and morphological equilibrium. Since the late 19th century, the flood level along the Lower Tisza River has increased by 216 cm; further, since 1998, flood levels increased by over 80 cm without an increase in discharge. In addition, river stages for low flows have decreased, and the water slope has decreased. These changes are likely connected to morphological changes in the channel (e.g., incision, narrowing, disappearance of point bars, intensifying mass movements), which have been driven by the complex response to human impacts. While the channel could adjust itself to convey larger floods after the cut-offs, the revetments impede the channel adjustment and contribute to the hydrological and morphological disequilibrium state along the Tisza River.

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