About once a month, one of our users sends an e-mail to EarthTrends with a variation of the above, usually with an emphasis on resource consumption in the United States. Resource consumption can be tricky to measure. Is monetary expenditure a good proxy for consumption? What about the quantity of objects consumed? How do we account for recycling, or expenditures in the service sector? We'll consider a few different angles on the consumption question below.

In monetary terms, most consumption still occurs in industrialized nations; according to the World Bank, the 2.3 billion residents of low-income countries accounted for less than 3% of public and private consumption in 2004, while the 1 billion residents of high-income countries consumed more than 80% of the global total (See Figure 1.) In this same year the United States accounted for 4.6 percent of the world's population and 33 percent of global consumption--more than $9 trillion U.S. dollars.

More than 80 percent of the world's energy consumption depends on fossil fuels. However, the oil, coal, and natural gas that serve the majority of our energy needs present different challenges in terms of production, transport, scarcity, and greenhouse gas (GHG) emissions.

Natural gas has been viewed as environmentally preferable to other fossil fuels due to its lower level of GHG emissions; per unit of energy generated, natural gas combustion emits an average of 42 and 16 percent less carbon dioxide (CO2) than coal and oil, respectively. However, the transport of natural gas is more expensive than other fossil fuels, and some studies estimate that gas leakage on poorly maintained pipelines could result in substantial emissions of methane, another GHG.

At EarthTrends, we focus on international environmental statistics and analyses, frequently writing about daunting global challenges such as poverty, climate change, and biodiversity loss. However, many of our site's visitors--particularly those in developed countries--have asked us for more information on how individual efforts can contribute to positive change in these areas of concern.

In response, we've taken a break from our quantitative data to compile a summary of simple actions that one can take in four areas--water, waste, energy, and biodiversity--to live a more environmentally-friendly and sustainable lifestyle.

Water scarcity--defined as the annual availability of less than 1,000 cubic meters of water per person--already affects 40 percent of the world population. By 2025, this figure could rise to 66 percent as a result of population growth, climate change and water pollution. What if we could turn seawater, which accounts for 97 percent of the earth's water resources, into drinkable water? We can. Desalination technologies have existed for hundreds of years, although the cost of desalination remains prohibitively high for most countries.

Gender inequality is a problem faced by all regions of the developed and developing world. In only four countries--Denmark, Finland, Norway, and Sweden--do women have legal, social and economic rights roughly equal to those of men. The global consequences of gender inequality transcend all aspects of human welfare, including poverty, disease, education, and environmental health. As a result, empowering women has been identified as a necessary condition for improving the lives of the most vulnerable men, women and children worldwide.

Each year, natural and manmade disasters affect millions of people worldwide, causing countless injuries and deaths and costing billions of dollars. During the past month alone, severe drought and flooding have impacted nearly 7.5 million people in Bolivia, Indonesia, Madagascar, Somalia, Kenya and Ethiopia. In Bangladesh, nearly 100,000 are coping with a deadly wave of extreme cold weather that has already killed 130 people. Three years ago, a summer heat wave claimed over 52,000 lives in Europe.

Electronic waste, also known as e-waste, is the fastest growing component of municipal waste worldwide with 20-50 million tonnes generated annually. In the United States alone, 14-20 million PCs are thrown out each year. Finding new methods and locations to dispose of this waste is becoming problematic. E-waste is laden with toxic heavy metals such as lead, mercury and cadmium that can leach into water, soils and the atmosphere, posing significant environmental and human health risks.

The Kyoto Protocol is currently the only legally-binding international agreement that seeks to tackle the challenges of global warming. By setting individual greenhouse gas (GHG) reduction targets for 35 industrialized countries and members of the European Community (known as Annex I Parties), the Protocol aims to cut global emissions by 5% of 1990 levels by 2012.

Wetlands are areas of land that are a combination of terrestrial and aquatic ecosystems. Inland wetlands include creeks, swamps, marshes, and shallow aquifers while coastal wetlands include estuaries, tidal basins, marshes, deltas and mangroves. These water covered areas are biologically diverse and provide a habitat for a wide variety of fish, amphibians, water fowl and other birds, insects, and mammals. 

The Millennium Development Goals (MDGs) are a set of 8 goals that were agreed upon by United Nations Member States in September 2000 following the United Nations World Summit on Sustainable Development in Johannesburg. The combined objective of the Millennium Development Goals is to address the problem of underdevelopment and eradicate poverty.