MIT tracks carbon footprints of different lifestyles

In America, even the smallest footprints are large

CAMBRIDGE, Mass.--Whether you live in a cardboard box or a luxurious mansion, whether you subsist on homegrown vegetables or wolf down imported steaks, whether you're a jet-setter or a sedentary retiree, anyone who lives in the U.S. contributes more than twice as much greenhouse gas to the atmosphere as those living in the rest of the world.

An MIT class has estimated the carbon emissions of Americans in a wide variety of lifestyles--from the homeless to multimillionaires, from Buddhist monks to soccer moms--and compared them to those of other nations. The somewhat disquieting bottom line is that in the United States, even the people with the lowest usage of energy are still producing, on average, more than double the global per-capita average. And those emissions rise steeply from that minimum as people's income increases: The class estimated Bill Gates' impact as about 10,000 times the average.

“Regardless of income, there is a certain floor below which the individual carbon footprint of a person in the U.S. will not drop,” says Timothy Gutowski, professor of mechanical engineering, who taught the class that calculated the rates of carbon emissions.

The results will be presented this May 19-20 at the IEEE International Symposium on Electronics and the Environment in San Francisco.

While it may seem surprising that even people whose lifestyles don't appear extravagant--the homeless, monks, children--are responsible for significant greenhouse gas emissions, one major factor is the array of government services that are available to everyone in the United States. These basic services-including police, roads, libraries, the court system and the military-were allocated equally to everyone in the country in this study. Other services that are more specific, such as education or Medicare, were allocated only to those who actually make use of them.

The students conducted detailed interviews or made detailed estimates of the energy usage of 18 lifestyles, spanning the gamut from a vegetarian college student and a 5-year-old up to the ultra-rich-Oprah Winfrey and Bill Gates. The energy impact for the rich was estimated from published sources, while all the others were based on direct interviews. The average annual carbon dioxide emissions per person, they found, was 20 metric tons, compared to a world average of four tons.

But the “floor” below which nobody in the U.S. can reach, no matter what their energy choices, turned out to be 8.5 tons, the class found. That was the usage calculated for a homeless person who ate in soup kitchens and slept in homeless shelters. The person with the lowest energy usage was a Buddhist monk who spent six months of every year living in the forest and had total annual spending of $12,500. His carbon footprint was 10.5 tons.