Ground Truth Studies Teacher Handbook - Aspen Global Change ...

A Global Change Primer (continued)
2 Biogeochemical Dynamics
An essential part of reliably predicting change on a global scale is an adequate understanding of the cycling of the
key nutrient elements — carbon, nitrogen, oxygen, sulfur, and phosphorous — through their major reservoirs: the
oceanic and freshwater aquatic systems, the solid Earth component, the biosphere, and the atmosphere. Subelements
include: greenhouse warming, acid deposition, deforestation, coastal pollution, and ozone depletion.
3 Ecological Systems and Dynamics
These are important to global change as both cause and effect. Ecosystems provide food and fiber for humans and
wildlife. They also influence air and water quality, the amount and distribution of surface and ground water, and the
habitats of both human and wildlife. Therefore, ecosystem destruction has direct effects on our economic and social
well-being. Variables such as temperature, precipitation, and biotic interactions ultimately control the distribution of
species. Species, in turn, influence the characteristics of ecosystems, and ecosystems influence the physical environment
through such phenomena as reflectance, evapotranspiration, and the emissions of important greenhouse gases,
such as carbon dioxide and methane. Therefore, ecosystems with altered structural and functional properties can
have feedback effects on the physical and chemical environment. Sub-elements include: biodiversity, coastal
pollution, sea level rise, erosion, ozone depletion, greenhouse warming, and acid deposition.
4 Earth System History
The Earth’s geologic record provides a valuable source of information about past changes in climate, ecosystems,
hydrologic conditions, and landscapes. Evidence of major variations in sea level, lake and ground water levels,
extent of glacier ice and sea ice, changes in atmospheric composition, and dramatic changes in ecosystems in the past
provide us with important insights into what the future may hold. We learn about natural climate variability by
indicators such as tree rings, ice cores, fossils, and sediment. Information about the causes, rates, and consequences
of climate change can also be extracted from the geologic record. Such information can improve our ability to make
predictions about future climate change.
5 Human Interactions
Human activity is a critical element in global change, both in terms of initiating processes of change, as well as
altering ongoing processes. Research into the human dimensions of global change will help us to understand the
patterns of direct human action or impact, as well as the indirect structural and institutional causes of change in Earth
systems, including such factors as economic markets, national legal and regulatory systems, and social and economic
aspirations of various nations. Such research will provide the scientific background for public policy studies, which
should address the response of human institutions to global change in terms of both mitigation strategies and
processes of adaptation.
© ASPEN GLOBAL CHANGE INSTITUTE 1995 GROUND TRUTH STUDIES
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