The researchers focused on the ecological footprint, a measure of how consumption may affect the environment by taking account of food and fiber production, energy use, and human use of land for living space and other purposes.

Population size and affluence have long been hypothesized to be primary drivers of environmental impact, however doubts over their relative impact remained due to a lack of extensive testing and contradictory arguments in regards to the impact of affluence. In the study Dietz and colleagues estimate the relative importance of the hypothesized drivers of environmental impact at the nation-state level. They then utilize their results to project future levels of stressors.

Restricting their data to countries of at least one million people, Dietz and colleagues 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. The relative importance of each hypothesized driver on environmental impact was then estimated and used to project future levels of stressors. They found that increased affluence exacerbates environmental impacts and, when combined with population growth, will substantially increase the human footprint on the planet.

Researchers projected 20 nations that will have the largest ecological footprints in 2015, with the United States, China and India, topping the list. According to the study, the greatest absolute increase will occur with China and India, where both population and economic growth, represent 37 percent of the increase in the global human footprint.

"Increasing energy efficiency to counteract these impacts is feasible, but would need a focused international effort to succeed," say the researchers.

According to the study, one advantage to the rapid growth of these two nations is with the development of their infrastructures in the early 21st Century: China and India are positioned to invest in more efficient technologies.

"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," say the scientists.

Amazonia revealed: forest degradation and the loss of ecosystem goods and services in the Amazon Basin

Also appearing in the February issue of Frontiers, researchers review newly revealed changes in the Amazon rainforests and the ecosystem services they provide.

The Amazon Basin is one of the world's most important bioregions, harboring rich array of plant and animal species and offering a wealth of goods and services to society. For years, ecological science has shown how large scale forest clearings cause declines in biodiversity and the availability of forest products. Yet some important changes in the rainforests, and in the ecosystem services they provide, have been underappreciated until recently.

Emerging research indicates land use in the Amazon goes far beyond clearing large areas of forest; selective logging and other canopy damage is much more pervasive than once believed. Deforestation causes collateral damage to the surrounding forests - through enhanced drying of the forest floor, increased frequency of fires, and lowered productivity. The loss of healthy forests can degrade key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance and river flow, the modulation of regional climate patterns, and the amelioration of infectious diseases.

Authors: Jonathan Foley (University of Wisconsin, Madison); Gregory Asner (Carnegie Institute of Washington); Marcos Heil Costa (Federal University of Vicosa, Brazil); Michael Coe (Woods Hole Research Center); Ruth DeFries (University of Maryland, College Park); Holly Gibbs, Erica Howard, Sarah Olson, Jonathan Patz, and Navin Ramankutty (University of Wisconsin, Madison), and Peter Snyder (University of Illinois, Urbana).

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