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Population, consumption drive global climate change and environmental degradation

PULLMAN, Wash. – A new study by a Washington State University researcher and his colleagues pinpoints the causes of a recent finding by a working group of the Inter-Governmental Panel on Climate Change that global climate warming is due to human activities.

The principal factors affecting climate change are the growth of human population and consumption, according to research by WSU sociologist Eugene A. Rosa and his colleagues Richard York, of the University of Oregon, and Thomas Dietz, of Michigan State University.

In fact, their findings suggest the impact of these two environmental stressors is so profound that they may outpace any potential environmental benefits from industrial modernization and improving technologies. Urbanization, economic structure, age of population, and other analyzed factors have little effect, according to their research, which was published in an article entitled, "Driving the human ecological footprint," in the February issue of “Frontiers in Ecology and the Environment.”

Through the creation of a research program called STIRPAT, the trio of researchers has developed a highly refined way of systematically and empirically assessing the human-generated factors that drive adverse environmental impacts. Using the STIRPAT statistical model, they have examined various greenhouse gases and the "ecological footprint," a quantitative measurement of the stress placed on the environment by demands for available lands and resources to meet the need for food, housing, transportation, consumer goods and services.

One of the clear conclusions arising from this and earlier work by the three researchers, Rosa said, is that technology and modernization alone won't rescue our planet from the detrimental environmental impacts of industrialization and other human activities.

Restricting their data to countries of at least one million people, they calculated basic forms of consumption, including crops, meat, energy, and living space, using data from the World Wide Fund for Nature. United Nations reports were used to measure human well-being, population, and urbanization, while data from the World Bank were used to determine economic influences.

While population size and consumption have long been considered the primary drivers of environmental impact, a lack of extensive testing and contradictory arguments regarding the impact of consumption left the relative extent of their influence in doubt. For their most recent study, Rosa and his colleagues first estimated the relative importance of a wide variety of the various posited drivers of environmental impact at the nation-state level With a trimmed statistical model they then projected future levels of environmental stressors.

Their study projected that 20 nations will have the largest ecological footprints by 2015, with the United States, China and India, topping the list. They estimate that the greatest absolute increase will occur in China and India, where their combined population and economic growth represent 37 percent of the total increase in the human footprint globally to 2015.

One advantage to the rapid growth of China and India is the development of their infrastructures in the early 21st Century, which positions both countries to invest in more efficient technologies, the researchers concluded. Unfortunately, however, their study also demonstrated such advances will do little to offset the detrimental environmental impact of their growing populations and consumption.

“Increasing … efficiency to counteract these impacts is feasible, but would need a focused international effort to succeed," they conclude in their study.

"China would need to improve its technical efficiency at a rate of about 2.9 percent per year, and India by about 2.2 percent per year to offset the projected growth of their ecological footprints," they wrote.

In fact, in a variety of cross-national analyses of the driving forces behind environmental degradation, the model persistently identifies population size as the primary influence on the global environment, Rosa said.

The model demonstrates also that there are factors creating dramatic inequities in the amount of resource consumption and waste emissions between the earth's nations. While population in all nations is the major influence on the environment, the detrimental environmental impacts are most pronounced in nations in which the population is the most affluent, he said.

"With few exceptions, we find that the environmental impacts of population growth increase with consumption," Rosa said. "The effect is much higher in developed nations than in under-developed nations. For instance, the ecological footprint of the U.S. is about 20 times that of a country like Bangladesh."

The findings by Rosa and his colleagues challenge a number of environmental theories that have emerged over the past decade suggesting that improving technological efficiency and declines in the resource requirements of modernizing nations will ultimately lead to environmental sustainability, offsetting the negative impacts of ever-increasing growth in population and human consumption.

"When we analyze the ability of increasing technological efficiency to counteract the environmental impacts of increasing population and consumption, we find that even if we were to achieve a four-fold increase in efficiency among all nations - which is a very unrealistic expectation - negative environmental impacts still increase, although at a much reduced rate," he said.

For some specific negative environmental impacts, such as that from carbon dioxide emissions, the researchers have found there is a theoretical point at which growth in a nation's per capita gross domestic product begins to produce benefits sufficient to begin to offset negative environment influences. But while such hypothetical levels of economic growth can be successfully modeled, Rosa argues they are not realistically attainable.

"For instance, our data show that, under best circumstances, every nation in the world would need to achieve a gross domestic product per capita of $10,000 or more, to achieve environmental sustainability on a global level for carbon dioxide, " he said. "This is a highly unrealistic possibility, given that more than 75 percent of the world's nations have a GDP per capita of less than $5,000. Many of these nations are in the Third World, where hope of sufficiently rapid economic expansion is all but impossible within a viewable horizon."

Such findings provide little support for the theories predicting a decline in a nation's environmental impacts in the mature stages of economic development, Rosa said.

"This suggests we're not likely to achieve ecological sustainability by continuing to pursue endless economic growth, ignoring our growing population and hoping for a last-minute technological fix that will solve our problems," he said.

Instead, Rosa believes achieving environmental sustainability will require new and complex programs and strategies. Such efforts will need to address the rate of population growth, the question of how to reduce consumption practices without necessarily reducing quality of life, how scientific innovation can develop new types of resources and how increasingly efficient industrial and waste-treatment processes can be adopted.

"There is no magic bullet. The ramifications for our society are potentially profound," he said. "Achieving sustainability may require a fundamental change of values and changes in the way we have been doing things for a very long time."

Rosa is currently the Edward R. Meyer Distinguished Professor of Natural Resource and Environmental Policy in the Thomas S. Foley Institute for Public Policy and Public Service, past chair and professor of sociology, affiliated professor of fine arts, affiliated professor in environmental science and regional planning, and faculty associate in the Center for Integrated Biology.

His research has focused on environmental topics - particularly energy, technology and risk issues - with attention to both theoretical and policy concerns. His recent research is devoted to the complementary topics of global environmental change and risk assessment, with the focus of the first topic on structural features of national environments and the focus of the second on the decision processes for addressing environmental challenges.

In 2003, Rosa was among 348 individuals elected by their peers as fellows in the American Association for the Advancement of Science for his "pioneering research on technological risk, energy, and global environmental change and for innovative and effective service to the environmental social sciences" Earlier this year, he was chosen to deliver the 2007 WSU Distinguished Faculty Address, an annual honor recognizing the work of a faculty member whose achievements in research, scholarship and teaching place them in the front ranks of their discipline.

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