Quaternary Environmental Change in Southern Africa: Physical and Human Dimensions

2017 ◽  
Vol 158 ◽  
pp. 235-236
Author(s):  
Colin V. Murray-Wallace
Author(s):  
M.S. Humphries

Abstract Sediments are the most important source of Late Quaternary palaeoclimate information in southern Africa, but have been little studied from a geochemical perspective. However, recent advances in analytical techniques that allow rapid and near-continuous elemental records to be obtained from sedimentary sequences has resulted in the increasing use of elemental indicators for reconstructing climate. This paper explores the diverse information that can be acquired from the inorganic component of sediments and reviews some of the progress that has been made over the last two decades in interpreting the climatic history of southern Africa using elemental records. Despite the general scarcity of elemental records, excellent examples from the region exist, which provide some of the longest and most highly resolved sequences of environmental change currently available. Records from Tswaing crater and marine deposits on the southern KwaZulu-Natal coastline have provided rare glimpses into hydroclimate variability over the last 200 000 years, suggesting that summer rainfall in the region responded predominantly to insolation forcing on glacial-interglacial timescales. Over shorter timescales, lakes and wetlands found in the Wilderness embayment on the southern Cape coast and along the Maputaland coast in north-eastern South Africa have yielded highly-resolved elemental records of Holocene environmental change, providing insight into the changing interactions between tropical (e.g., El Niño-Southern Oscillation) and temperate (e.g., mid-latitude westerlies) climate systems affecting rainfall variability in the region. The examples discussed demonstrate the multiple environmental processes that can be inferred from elemental proxies and the unique insight this can provide in advancing our understanding of past climate change on different timescales. The interpretation of geochemical data can be complicated by the complex nature of sedimentary environments, various proxy assumptions and analytical challenges, and the reliability of sediment-based climate reconstructions is substantially enhanced through multi-proxy approaches.


Author(s):  
Diana Liverman ◽  
Brent Yarnal

The human–environment condition has emerged as one of the central issues of the new millennium, especially as it has become apparent that human activity is transforming nature at a global scale in both systemic and cumulative ways. Originating with concerns about potential climate warming, the global environmental change agenda rapidly enlarged to include changes in structure and function of the earth’s natural systems, notably those systems critical for life, and the policy implications of these changes, especially focused on the coupled human–environment system. Recognition of the unprecedented pace, magnitude, and spatial scale of global change, and of the pivotal role of humankind in creating and responding to it, has led to the emergence of a worldwide, interdisciplinary effort to understand the human dimensions of global change. The term “global change” now encompasses a range of research issues including those relating to economic, political, and cultural globalization, but in this chapter we limit our focus to global environmental change and to the field that has become formally known as the human dimensions of global (or global environmental) change. We also focus mainly on the work of geographers rather than attempting to review the whole human dimensions research community. Intellectually, geography is well positioned to contribute to global environmental change research (Liverman 1999). The large-scale human transformation of the planet through activities such as agriculture, deforestation, water diversion, fossil fuel use, and urbanization, and the impacts of these on living conditions through changes in, for example, climate and biodiversity, has highlighted the importance of scholarship that analyzes the human–environmental relationship and can inform policy. Geography is one of the few disciplines that has historically claimed human–environment relationships as a definitional component of itself (Glacken 1967; Marsh 1864) and has fostered a belief in and reward system for engaging integrative approaches to problem solving (Golledge 2002; Turner 2002). Moreover, global environmental change is intimately spatial and draws upon geography-led remote sensing and geographic information science (Liverman et al. 1998). Geographers anticipated the emergence of current global change concerns (Thomas et al. 1956; Burton et al. 1978) and were seminal in the development of the multidisciplinary programs of study into the human dimensions of global change.


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