Future Environments of South America

2007 ◽  
Author(s):  
Thomas T. Veblen ◽  
Kenneth R. Young
Keyword(s):  
South America ◽  
Environmental Change ◽  
Environmental Changes ◽  
Human Impacts ◽  
Southern Oscillation ◽  
Physical Geography ◽  
Tierra Del Fuego ◽  
South American ◽  
Policy Options ◽  
Natural Processes

An important goal of this book has been to provide a comprehensive understanding of the physical geography and landscape origins of South America as important background to assessing the probabilities and consequences of future environmental changes. Such background is essential to informed discussions of environmental management and the development of policy options designed to prepare local, national, and international societies for future changes. A unifying theme of this book has been the elucidation of how natural processes and human activities have interacted in the distant and recent past to create the modern landscapes of the continent. This retrospective appreciation of how the current landscapes have been shaped by nature and humans will guide our discussion of possible future trajectories of South American environments. There is abundant evidence from all regions of South America, from Tierra del Fuego to the Isthmus of Panama, that environmental change, not stasis, has been the norm. Given that fact, the history, timing, and recurrence intervals of this dynamism are all crucial pieces of information. The antiquity and widespread distribution of changes associated with the indigenous population are now well established. Rates and intensities of changes related to indigenous activities varied widely, but even in regions formerly believed to have experienced little or no pre-European impacts we now recognize the effects of early humans on features such as soils and vegetation. Colonization by Europeans mainly during the sixteenth century modified or in some cases replaced indigenous land-use practices and initiated changes that have continued to the present. Complementing these broad historical treatments of human impacts, other chapters have examined in detail the environmental impacts of agriculture (chapter 18) and urbanism (chapter 20), and the disruptions associated with El Niño–Southern Oscillation events. The goal of this final synthesis is to identify the major drivers of change and to discuss briefly their likely impacts on South American environments and resources in the near and medium-term future. Our intent is not to make or defend predictions, but rather to identify broad causes and specific drivers of environmental change to inform discussions of policy options for mitigating undesirable changes and to facilitate potential societal adaptations to them.

Salicornia cuscoensis (Amaranthaceae/Chenopodiaceae), a new species from Peru (South America)

Phytotaxa ◽  
2017 ◽  
Vol 319 (3) ◽  
pp. 254 ◽  
Author(s):  
M. ÁNGELES ALONSO ◽  
MANUEL B. CRESPO ◽  
HELMUT FREITAG
Keyword(s):  
New Species ◽  
South America ◽  
Morphological Characters ◽  
Tierra Del Fuego ◽  
South American ◽  
Habitat Distribution ◽  
Closely Related Species ◽  
Molecular Analyses ◽  
Southern Patagonia ◽  
A New Species

The name Salicornia cuscoensis given to a plant from high Andean saltmarshes near Cusco [Cuzco] and Ayacucho, Peru (South America) is validated by a diagnosis and description. The main morphological characters that separate S. cuscoensis from other closely related species are creeping habit, delicate branches, inflorescence of short and thin spikes, and seed indumentum. The new species clearly differs from other perennial Salicornia taxa growing in high Andean saltmarshes such as S. pulvinata and S. andina. The former forms small compact cushions producing very short, few-flowered inflorescences. The latter shows woody stems and forms larger rounded carpets. Morphologically, S. cuscoensis is also similar to S. magellanica, a species growing along the seashore in southern Patagonia and Tierra del Fuego, but the latter has shorter and wider inflorescences and larger seeds with a different type and arrangement of indumentum. Molecular analyses also supported the separation of S. cuscoensis. Data on habitat, distribution and phylogenetic relationships are presented for the new species and its relatives, and an identification key is given for the South American taxa of the genus Salicornia.

scholarly journals The impact of the subtropical South Atlantic SST on South American precipitation

2008 ◽  
Vol 26 (11) ◽  
pp. 3457-3476 ◽  
Author(s):  
A. S. Taschetto ◽  
I. Wainer
Keyword(s):  
South America ◽  
Southern Oscillation ◽  
South Atlantic ◽  
Empirical Orthogonal Functions ◽  
Convergence Zone ◽  
South American ◽  
The South ◽  
Inter Tropical Convergence Zone ◽  
The Impact ◽  
Sst Anomalies

Abstract. The Community Climate Model (CCM3) from the National Center for Atmospheric Research (NCAR) is used to investigate the effect of the South Atlantic sea surface temperature (SST) anomalies on interannual to decadal variability of South American precipitation. Two ensembles composed of multidecadal simulations forced with monthly SST data from the Hadley Centre for the period 1949 to 2001 are analysed. A statistical treatment based on signal-to-noise ratio and Empirical Orthogonal Functions (EOF) is applied to the ensembles in order to reduce the internal variability among the integrations. The ensemble treatment shows a spatial and temporal dependence of reproducibility. High degree of reproducibility is found in the tropics while the extratropics is apparently less reproducible. Austral autumn (MAM) and spring (SON) precipitation appears to be more reproducible over the South America-South Atlantic region than the summer (DJF) and winter (JJA) rainfall. While the Inter-tropical Convergence Zone (ITCZ) region is dominated by external variance, the South Atlantic Convergence Zone (SACZ) over South America is predominantly determined by internal variance, which makes it a difficult phenomenon to predict. Alternatively, the SACZ over western South Atlantic appears to be more sensitive to the subtropical SST anomalies than over the continent. An attempt is made to separate the atmospheric response forced by the South Atlantic SST anomalies from that associated with the El Niño – Southern Oscillation (ENSO). Results show that both the South Atlantic and Pacific SSTs modulate the intensity and position of the SACZ during DJF. Particularly, the subtropical South Atlantic SSTs are more important than ENSO in determining the position of the SACZ over the southeast Brazilian coast during DJF. On the other hand, the ENSO signal seems to influence the intensity of the SACZ not only in DJF but especially its oceanic branch during MAM. Both local and remote influences, however, are confounded by the large internal variance in the region. During MAM and JJA, the South Atlantic SST anomalies affect the magnitude and the meridional displacement of the ITCZ. In JJA, the ENSO has relatively little influence on the interannual variability of the simulated rainfall. During SON, however, the ENSO seems to counteract the effect of the subtropical South Atlantic SST variations on convection over South America.

scholarly journals Hindcasts of Tropical Atlantic SST Gradient and South American Precipitation: The Influences of the ENSO Forcing and the Atlantic Preconditioning

2009 ◽  
Vol 22 (9) ◽  
pp. 2405-2421 ◽  
Author(s):  
Huei-Ping Huang ◽  
Andrew W. Robertson ◽  
Yochanan Kushnir ◽  
Shiling Peng
Keyword(s):  
South America ◽  
General Circulation ◽  
Southern Oscillation ◽  
Boreal Winter ◽  
South American ◽  
Primary Role ◽  
Tropical Atlantic ◽  
Boreal Spring ◽  
Sst Anomaly ◽  
Sst Gradient

Abstract Hindcast experiments for the tropical Atlantic sea surface temperature (SST) gradient G1, defined as tropical North Atlantic SST anomaly minus tropical South Atlantic SST anomaly, are performed using an atmospheric general circulation model coupled to a mixed layer ocean over the Atlantic to quantify the contributions of the El Niño–Southern Oscillation (ENSO) forcing and the preconditioning in the Atlantic to G1 in boreal spring. The results confirm previous observational analyses that, in the years with a persistent ENSO SST anomaly from boreal winter to spring, the ENSO forcing plays a primary role in determining the tendency of G1 from winter to spring and the sign of G1 in late spring. In the hindcasts, the initial perturbations in Atlantic SST in boreal winter are found to generally persist beyond a season, leaving a secondary but nonnegligible contribution to the predicted Atlantic SST gradient in spring. For 1993/94, a neutral year with a large preexisting G1 in winter, the hindcast using the information of Atlantic preconditioning alone is found to reproduce the observed G1 in spring. The seasonal predictability in precipitation over South America is examined in the hindcast experiments. For the recent events that can be validated with high-quality observations, the hindcasts produced dryness in boreal spring 1983, wetness in spring 1996, and wetness in spring 1994 over northern Brazil that are qualitatively consistent with observations. An inclusion of the Atlantic preconditioning is found to help the prediction of South American rainfall in boreal spring. For the ENSO years, discrepancies remain between the hindcast and observed precipitation anomalies over northern and equatorial South America, an error that is partially attributed to the biased atmospheric response to ENSO forcing in the model. The hindcast of the 1993/94 neutral year does not suffer this error. It constitutes an intriguing example of useful seasonal forecast of G1 and South American rainfall anomalies without ENSO.

Integrated reconstruction of Holocene millennial-scale environmental changes in Tierra del Fuego, southernmost South America

2014 ◽  
Vol 399 ◽  
pp. 294-309 ◽  
Author(s):  
Nicolás Waldmann ◽  
Ana Maria Borromei ◽  
Cristina Recasens ◽  
Daniela Olivera ◽  
Marcelo A. Martínez ◽  
...  
Keyword(s):  
South America ◽  
Environmental Changes ◽  
Tierra Del Fuego ◽  
Millennial Scale

The Physical Geography of South America

2007 ◽  
Author(s):  
Thomas Veblen ◽  
Kenneth Young ◽  
Antony Orme
Keyword(s):  
South America ◽  
Amazon Basin ◽  
Physical Geography ◽  
Environmental Literature ◽  
South American ◽  
High Mountains ◽  
Natural Landscape ◽  
Modern Agriculture ◽  
Body Of Knowledge ◽  
Main Components

The Physical Geography of South America, the eighth volume in the Oxford Regional Environments series, presents an enduring statement on the physical and biogeographic conditions of this remarkable continent and their relationships to human activity. It fills a void in recent environmental literature by assembling a team of specialists from within and beyond South America in order to provide an integrated, cross-disciplinary body of knowledge about this mostly tropical continent, together with its high mountains and temperate southern cone. The authors systematically cover the main components of the South American environment - tectonism, climate, glaciation, natural landscape changes, rivers, vegetation, animals, and soils. The book then presents more specific treatments of regions with special attributes from the tropical forests of the Amazon basin to the Atacama Desert and Patagonian steppe, and from the Atlantic, Caribbean, and Pacific coasts to the high Andes. Additionally, the continents environments are given a human face by evaluating the roles played by people over time, from pre-European and European colonial impacts to the effects of modern agriculture and urbanization, and from interactions with El Niño events to prognoses for the future environments of the continent.

scholarly journals Global tropospheric ozone variations from 2003 to 2011 as seen by SCIAMACHY

2016 ◽  
Vol 16 (2) ◽  
pp. 417-436 ◽  
Author(s):  
F. Ebojie ◽  
J. P. Burrows ◽  
C. Gebhardt ◽  
A. Ladstätter-Weißenmayer ◽  
C. von Savigny ◽  
...  
Keyword(s):  
South America ◽  
North Atlantic ◽  
Tropospheric Ozone ◽  
Southern Oscillation ◽  
South American ◽  
Quasi Biennial Oscillation ◽  
The Pacific ◽  
The Tropics ◽  
Biennial Oscillation ◽  
South American Continent

Abstract. An analysis of the tropospheric ozone (O3) columns (TOCs) derived from SCIAMACHY limb-nadir-matching (LNM) observations during the period 2003–2011, focusing on global variations in TOC, is described. The changes are derived using a multivariate linear regression model. TOC shows changes of −0.2 ± 0.4, 0.3 ± 0.4, 0.1 ± 0.5 and 0.1 ± 0.2 % yr−1, which are not statistically significant at the 2σ level in the latitude bands 30–50° N, 20° S–0, 0–20° N and 50–30° S, respectively. Tropospheric O3 shows statistically significant increases over some regions of South Asia (1–3 % yr−1), the South American continent (up to 2 % yr−1), Alaska (up to 2 % yr−1) and around Congo in Africa (up to 2 % yr−1). Significant increase in TOC is determined off the continents including Australia (up to 2 % yr−1), Eurasia (1–3 % yr−1) and South America (up to 3 % yr−1). Significant decrease in TOC (up to −3 % yr−1) is observed over some regions of the continents of North America, Europe and South America. Over the oceanic regions including the Pacific, North Atlantic and Indian oceans, significant decreases in TOC (−1 to −3 % yr−1) were observed. In addition, the response of the El Niño–Southern Oscillation (ENSO) and quasi-biennial oscillation (QBO) to changes in TOC for the period 2003–2011 was investigated. The result shows extensive regions, mostly in the tropics and Northern Hemisphere extratropics, of significant ENSO responses to changes in TOC and a significant QBO response to TOC changes over some regions.

scholarly journals Precipitation changes in the South American Altiplano since 1300 AD reconstructed by tree-rings

2012 ◽  
Vol 8 (2) ◽  
pp. 653-666 ◽  
Author(s):  
M. S. Morales ◽  
D. A. Christie ◽  
R. Villalba ◽  
J. Argollo ◽  
J. Pacajes ◽  
...  
Keyword(s):  
Tree Ring ◽  
Environmental Changes ◽  
Southern Oscillation ◽  
Ring Width ◽  
Warming Trend ◽  
Future Climate Change ◽  
South American ◽  
The South ◽  
Economic Activities ◽  
Precipitation Reconstruction

Abstract. Throughout the second half of the 20th century, the Central Andes has experienced significant climatic and environmental changes characterized by a persistent warming trend, an increase in elevation of the 0 °C isotherm, and sustained glacier shrinkage. These changes have occurred in conjunction with a steadily growing demand for water resources. Given the short span of instrumental hydroclimatic records in this region, longer time span records are needed to understand the nature of climate variability and to improve the predictability of precipitation, a key factor modulating the socio-economic development in the South American Altiplano and adjacent arid lowlands. In this study we present the first quasi-millennial, tree-ring based precipitation reconstruction for the South American Altiplano. This annual (November–October) precipitation reconstruction is based on the Polylepis tarapacana tree-ring width series and represents the closest dendroclimatological record to the Equator in South America. This high-resolution reconstruction covers the past 707 yr and provides a unique record characterizing the occurrence of extreme events and consistent oscillations in precipitation. It also allows an assessment of the spatial and temporal stabilities of the teleconnections between rainfall in the Altiplano and hemispheric forcings such as El Niño-Southern Oscillation. Since the 1930s to present, a persistent negative trend in precipitation has been recorded in the reconstruction, with the three driest years since 1300 AD occurring in the last 70 yr. Throughout the 707 yr, the reconstruction contains a clear ENSO-like pattern at interannual to multidecadal time scales, which determines inter-hemispheric linkages between our reconstruction and other precipitation sensitive records modulated by ENSO in North America. Our reconstruction points out that century-scale dry periods are a recurrent feature in the Altiplano climate, and that the future potential coupling of natural and anthropogenic-induced droughts may have a severe impact on socio-economic activities in the region. Water resource managers must anticipate these changes in order to adapt to future climate change, reduce vulnerability and provide water equitably to all users.

scholarly journals The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model

2016 ◽  
Vol 12 (4) ◽  
pp. 961-979 ◽  
Author(s):  
Christopher M. Colose ◽  
Allegra N. LeGrande ◽  
Mathias Vuille
Keyword(s):  
South America ◽  
Oxygen Isotope ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
Hydrologic Cycle ◽  
South American ◽  
Last Millennium ◽  
Continental Scale ◽  
The Impact ◽  
Tropical South America

Abstract. Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-Intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El Niño–Southern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850 CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium. An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records. Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the "amount effect". During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is larger than the rather weak and spatially less coherent precipitation signal, complicating the isotopic response to changes in the hydrologic cycle.

Testing ecological and environmental changes during the last 6000 years: a multiproxy approach based on the bivalve Tawera gayi from southern South America

2011 ◽  
Vol 91 (7) ◽  
pp. 1413-1427 ◽  
Author(s):  
Sandra Gordillo ◽  
Julieta Martinelli ◽  
Javiera Cárdenas ◽  
M. Sol Bayer
Keyword(s):  
Stable Isotopes ◽  
South America ◽  
Late Holocene ◽  
Environmental Changes ◽  
Growth Dynamics ◽  
Tierra Del Fuego ◽  
Physical Factors ◽  
Geological Time ◽  
Southern South America ◽  
Ecological Variability

This paper evaluates if the bivalve Tawera gayi from southern South America represents an opportunity to test ecological variability and environmental changes during the last 6000 years in southern South America. For this purpose, we analyse both modern and fossil (mid-to-late Holocene) T. gayi shells from Tierra del Fuego using different techniques, including taphonomy, stable isotopes, cathodoluminiscence (CL) and linear morphometrics. Taphonomic analysis shows that differences between modern and fossil shells appear best related to local variations of physical factors such as current speed, wave action and freshwater input along the non-uniform Beagle Channel coast. However, slight changes of hydraulic energy regimes throughout the Holocene cannot be ruled out. The analysis of stable isotopes on T. gayi shells indicates a mixing of oceanic waters with freshwater from precipitation, river runoff and glacier meltwater during the mid-to-late Holocene. The high depletion of δ18O at ~4400 years before present would be associated with a period of warmer temperatures, the so-called Hypsithermal. Under CL modern and fossil T. gayi shells show a well defined pattern related to the growth dynamics of the shell, which can lead to a better understanding of its biology, adding details to further palaeoenvironmental analysis. Finally, conventional metrics shows that fossil T. gayi shells are smaller and shorter than modern shells. These differences could be related to Holocene environmental changes, but here are best explained on the basis of a predator–prey relationship. This study shows that T. gayi may be a good candidate for looking at evidences of environmental changes in southern South America, and multi-proxy data are necessary to better understand the driving mechanisms of ecological variability and changes over short geological time intervals of few thousands of years.

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