Global Change: Institute of International Studies, UC Berkeley
he term "global change" encompasses all aspects of global environmental change and degradation, and the following chapters address the human and social dimensions of global change. These authors speak both of the ways that humans are changing the face of the earth and the impacts that these changes ultimately may have on our lives.
The I=PAT (Impact = Population x Affluence per capita x Technology) formula has been used by social scientists as a model for describing global change, and each of the chapters in this part deals with a piece of that equation. Paul Ehrlich describes the population and affluence variables, Rosamond Naylor describes the Green Revolution in rice agriculture (a part of the technology variable), Billie Lee Turner describes a new research program aimed at quantifying the driving forces behind the PAT side of the equation, Ingrid Burke et al. provide an example of a modeling effort to quantify the impact of land use on soil carbon, and Thomas Homer-Dixon uses the equation to understand regions vulnerable to environmentally driven conflict. As Turner discusses, global change has only recently been addressed by social scientists and much of the work presented here is still in relative infancy. Homer-Dixon's appendices give an example of how the important questions are still being formulated and debated. A theoretical framework that will satisfy both the physical and social scientists has yet to be described.
e begin this part with Paul Ehrlich and a discussion of population growth as a primary driving force behind global change. Ehrlich describes the impacts of population growth on greenhouse gases, ozone depleting chemicals, and the spread of the AIDS virus. He also summarizes some of the economic aspects of global change and the relative contributions to the problem by rich and poor countries. We are introduced to the issue of how global change is likely to exacerbate hunger, creating a potential negative feedback for environmental degradation. This paper is concluded with a brief discussion of ways to address the problem of population growth.
Rosamond Naylor then gives us a history of the Green Revolution and outlines the possible future for increased food resources in the rice-based farming systems of Asia. Naylor emphasizes that poverty and hunger are strong driving factors in environmental degradation. She sees three major priorities that must be met to mitigate the potential environmental impacts of hunger: provision of adequate food resources, adequate employment and livelihood, and adequate settlement areas. Naylor discusses the directions in rice development that may lead to increased yields and concludes that it is not clear how to reach the yields required to feed Asia's growing population. Substitutions or adjustments may be necessary to reach the food goals and there may be trade-offs between short-term hunger alleviation and long-term agricultural productivity gains. Jeff Romm extends the discussion of rice production as a source of greenhouse gases to emphasize the importance of viewing this source in its social context.
illie Lee Turner discusses an international research initiative, the Human Dimensions of Global Change, which aims to understand the human driving forces behind physical changes in land use and land cover. He is interested in how one might generate a model that will allow a full understanding of the primary driving forces that cause humans to change the earth's surface characteristics and that lead to environmental degradation. He notes that there are many local case studies but no useful theoretical basis for building a global model. Turner's goal is to quantify usefully the I=PAT relationship and develop an understanding of the relationships among, and the forces behind, the variables. Turner's discussion is complemented by the comments of Joseph Sax, who views the issue of land cover change from the historical legal perspective of the Lockean model of property rights.
ngrid Burke and her colleagues describe a regional modeling effort like that envisioned by Turner for the entire globe. Burke et al use satellite imagery and digital databases with a statistical model to quantify the relationships between land use, surface materials (percent sand and clay), climatic parameters (temperature and precipitation), and soil carbon for the central Great Plains. Soil carbon is used as a proxy for ecosystem health in this model. The simulations suggest that 44 percent of the original soil carbon was lost during the first fifty years the area was cultivated. The model also suggests that physical parameters (soil texture and climate) account for about two-thirds of the spatial variability of land use in this region. Social, cultural, and economic factors account for the remaining variability in land use.
inally, Thomas Homer-Dixon describes the possibility for conflict that arises from a deteriorating resource base. He discusses the four types of environmental change most likely to cause conflict and the types of conflict that are likely to result. Homer-Dixon uses the I=PAT equation to identify regions vulnerable to environmentally driven conflicts and discusses case studies from Senegal and the Philippines. He argues that environmental change can be both a dependent or an independent variable in creating conflict. Environmental change may result from either human or natural causes and may be transient or irreversible. In contrast to the research outlined by Turner, Homer-Dixon suggests that these interactions justify studying environmental degradation as a separate variable and not just as the result of political, social, and cultural systems.
hese articles raise questions about how we cause global change and how we respond to global change. Global environmental change is likely to threaten our most basic needs for food, shelter, income, and security. Clearly the people most vulnerable to the impacts of global environmental change are those already on the bottom of the economic and social pyramid. They suggest areas where research is crucial to address the possible social implications of global change, both scientifically in increasing the production of food resources as environments change, and socially in understanding how we as a species drive and respond to the change. While the population pressure described by Ehrlich may be a primary driving force for environmental degradation, the beliefs and policies that cause us to overpopulate and degrade the environment, and finally to use violence as a means of acquiring or protecting environmental resources, need more focused attention.
See also: Introduction to Part III: Policy and Legal Responses
Back to Ecological and Social Dimensions of Global Change.
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