Republished from my original 2007 post on the comprehensive environmental impact model I developed for the EVO Tree.

Many complex factors go into defining one’s environmental impact. Of course, small actions – like switching to compact fluorescent light bulbs or recycling plastic bottles – add up and are significant. But we intuitively know there’s more to it than that.

To live sustainably we first have to understand the many different impacts of our consumption – from energy use and CO2, to air and water pollution — and how these impacts affect the planet as a whole. Being a modern-day Homo Sapiens is complicated, but fortunately, there are several helpful scientific models that give us a way to measure our environmental impacts directly.

EVO’s Total Environmental Impact (TEI) model draws from two well-regarded scientific models. The first is the Ecological Footprint developed by the Global Footprint Network and Redefining Progress. The second is the Union of Concerned Scientists Consumer’s Guide to Effective Environmental Choices. The EVO model assimilates the data from these two sources and applies them to EVO’s eight consumption categories — Auto, Food, Home & Energy, Lifestyle, Body, Travel and Clothing.

In addition to the two main computation models listed above, EVO pulls in recent (2001-2006) data from the following sources:

    * FuelEconomy.gov

    * Energy Information Administration

    * EnergyStar

    * Carnegie Mellon Civil and Environmental Engineering (PDF)

    * U.S. General Accounting Office (PDF)

    * U..S Department of Agriculture

    * Environmental Protection Agency

    * Energy MIT Resource fact sheets

    * U.N. Environment Programme

    * Columbia University

    * U.S. Green Building Council

    * Worldwise

    * Bureau of Transportation Statistics

    * Environmental Defense

    * Food and Drug Administration

    * Centers for Disease Control and Prevention

    * U.S. Census Bureau

    * Ohio State University

    * Leopold Center for Sustainable Agriculture (PDF)

    * National Oceanic and Atmospheric Administration

    * Organic Trade Association

    * Healthways

    * American Water Works Association

    * Rocky Mountain Institute (PDF)

    * Sustainable Travel International

    * World Resources Institute

    * National Highway Traffic Safety Administration

    * World Energy Council (PDF)

    * U.S. Geological Survey

    * Lawrence Berkeley Labs Home Energy Saver (simulations)

    * World Wildlife Fund (PDF)

    * International Cotton Advisory Committee

…and many more. Combined, these sources give us a fairly accurate representation of how each of the eight categories of consumption affect the environment.

What do all the percentages mean?

In the chart above you can see the relative impact of each of the eight consumption categories. For a given product or service, the relative impact is determined by examining how much…

    * CO2 and CH4 (main greenhouse gases) it produces

    * Land it requires for its production

    * Water and air pollution it causes (not including CO2 and CH4)

    * Fresh water it requires

See the chart that summarizes the total environmental impacts by consumption category:

What are the biggest impacts?

For most of us, our biggest impact on the environment comes from driving. Yes, the automobile accounts for a full 21 percent of a typical American’s Total Environmental Impact, the largest single impact. By purchasing a hybrid or electric car, or following some of Gas Savings No-Brainers, you can easily cut this gargantuan impact in half.

Food is tied with Auto for first place in the impact department. Food has an enormous amount of “embodied energy” -- energy used for growing, harvesting, processing and shipping. One of the fastest ways to reduce your food impact is to eliminate food waste, which accounts for 20 percent of a typical American’s food impact. Red meat also has a very large impact (7.1 percent), equivalent to the energy of your home Space Heating and Lighting combined!

Home Energy is the next biggest category, representing 19 percent of a typical American’s environmental impact. Here, too, there are hundreds of ways to save energy that taken in aggregate will cut your energy use in half! It sounds too good to be true, but it’s actually much more attainable than you would think. Read the details in Energy Savings No-Brainers.

The Lifestyle category is the next biggest area of consumption and includes impacts associated with the consumption of paper and plastic goods, waste disposal and services. By recycling, composting and shopping wisely one can also easily cut this key area of consumption in half.

Is it really possible to significantly reduce my impact on the environment?

Yes! If each of us makes just a few key changes, we can easily reduce our individual TEI by over one thid. Here’s what one “target impact model” looks like:

The outer circle shows what a typical American consumes, the equivalent of roughly 9.6 hectares (or 24 acres) of land required for carbon sequestration, production of resources, and assimilation of wastes (not including pollution and water). The inner green circle defines what is considered truly sustainable by the UNEP – about 2 hectares or 1/5 of the typical impact of the average American. We believe that it is fairly easy to “split the difference” and reduce our impacts by one third. Even if 10 percent of U.S. households made this move, the positive impact on the environment and our atmosphere would be enormous – the equivalent of saving 80,000,000 acres of bioproductive land and preventing 100,000,000 pounds of CO2 from entering the atmosphere.

Read on to learn about the different types of environmental impacts. See the chart of a typical American's environmental impacts.

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