Friday, August 6, 2010

Carbon Footprints 101

What is a Greenhouse Gas?
There are a number of significant gases in our atmosphere which are referred to as “greenhouse gases” because they trap energy from the sun and keep the earth warm. Carbon Dioxide (CO2) is the one you hear about the most. Other greenhouse gases including methane, nitrous oxide, and CFCs (now banned in most of the world) all have much higher heat-trapping abilities, but exist in much smaller concentrations. CO2 adds by far the most warmth. This is why scientists tend to talk about all greenhouse gases in terms of the equivalent amount of CO2. Like so many things, greenhouse gases are good in the right concentration. Without them we would have an icy planet. But they have exceeded their concentration limits.

Why Should I Care?
It as a fact that our Earth is warming up. Scientists have spent decades trying to figure out why. Most scientists have concluded that the only way to explain this warming pattern pattern is to include the effect of greenhouse gases emitted by humans. Most CO2 comes from the combustion of fossil fuels. 350 parts per million is the number that leading scientists say is the safe upper limit for carbon dioxide in our atmosphere. We are now at about 390 parts per million which is why the group called for a day of global action last October and is planning another for this year.

What is a Carbon Footprint?
The website for the UK organization offers this succinct definition: Your carbon footprint is the sum of all CO2 emissions that are directly and indirectly associated with your activities over a given time frame (usually a year). 

How Do I Calculate My Footprint?
The United States Environmental Protection Agency (EPA) website has an excellent, easy-to-use calculator.

What Can I Do to Reduce It?
The EPA website offers many steps large and small for accomplishing this goal. You can also find suggestions at countless other sites and blogs, including this one. Some steps should be relatively easy to implement such as making fewer trips in your car or lowering your thermostat a degree or two. Many actions will seem totally logical once you think about them. Some will require more of a commitment, and perhaps some initial expense to put in place. There are numerous perks to reducing your footprint — beyond helping the planet. You will most likely improve your health and put some green back into your wallet in the long run. And, at least for this year, there are still energy tax credits.

In subsequent posts I will address two specific ways of reducing your footprint — switching to CFLs and purchasing carbon offsets when you travel. It’s too much for one post on a Friday. 

TGIF. And have a great weekend.


  1. Nice that you have it on the other social websites. You Go Girl! The sustainability director will have an exchange program for Cfls for incandescent light bulbs. Also there will be a energy audit for all city residents. stay tune!

  2. CP — The bulb exchange is part of the next post. Look for it on Monday or Tuesday. I already swapped some bulbs at the CitySeed market last Wed.