Humans as Geologic Agents

Homo sapiens is the only known species to consciously effect change to the Earth’s geologic environment. We reshape the Earth; intensify erosion; modify rivers; change local climates; pollute water resources, soils, and geologic media; and alter soils and the biosphere. We dig holes in it, remove parts of it, and bury highly toxic materials in it. In this volume, the authors explore human impact on the Earth and attempt to answer the following questions. What have we done to Terra? How fast have we effected change? Are the changes permanent? Are they good, or have we inadvertently caused more damage? Can we, should we, repair some or all of these changes? These are important questions for the geoscience community because, as those most knowledgeable about the Earth and its resources, geologists play a major role in sustaining and preserving the Earth.
The relative influence of humans on barrier islands: Humans versus geomorphology
*Present address, Stutz: Department of Environmental Studies, Dordt College, 498 Fourth Ave. NE, Sioux Center, Iowa, 51250 USA, [email protected]; e-mail, Pilkey—[email protected].
*Present address, Stutz: Department of Environmental Studies, Dordt College, 498 Fourth Ave. NE, Sioux Center, Iowa, 51250 USA, [email protected]; e-mail, Pilkey—[email protected].
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Published:January 01, 2005
Abstract
Humans are an integral component of barrier island systems throughout the world. The diversity of cultures (e.g., economics, politics) present has as much influence on barrier island evolution as the diversity of environments (e.g., climate) in which they are found.
The actions of humans affect three inherent properties of barrier islands: Each island is individually unique in its physical and ecological setting (affected by direct “local” human activity), each island is linked to a chain of adjacent islands through longshore transport (affected by “regional” activity elsewhere), and each island responds dynamically to environmental change through cross-shore transport (affected by regional activity and shoreline stabilization).
Geomorphic carrying capacity is the resilience of barrier islands to human impacts. Geomorphic risk factors serve as a basis for predicting resiliency, providing both a measure of dynamic change (erosion rate and storm frequency) and available buffer space (island width and elevation). As risk factors increase, the dynamic and spatial character of an island comes into greater conflict with human landscape elements and is more likely to be altered.
The relative influence of humans on barrier island evolution can be estimated by comparing the anthropogenic impacts on the three major island properties to the island's carrying capacity. When the three properties have been completely altered, an island becomes entirely human-dominated, or “terminated.” Carrying capacity can indicate whether stabilization, retreat, or abandonment is the best long-term management option.