When starting to calculate your footprint, you’ll need some information about your current lifestyle, including electricity, heat, and water usage and your travel habits.

There are a few caveats about carbon footprint calculators. Different  calculators can give you quite different results. One reason is they make different assumptions about the amount of the carbon you use for transportation. For the same number of miles driven, a longer trip at highway speeds is more efficient than in-town shorter trips. Another is the results might be in different units, sometimes without telling you what they are! In the US, we still use pounds and a ton is 2000 pounds. Internationally, the amount is specified in “metric tonnes” which is 1000 kilograms( about 2204 pounds) or about 10% larger than a US ton. Another caveat is whether the results are just for carbon dioxide or whether they include all greenhouse gases. Since it is awkward to specify the amounts of many different greenhouse gases from some activity, the impact of non-carbon dioxide gases are converted to an equivalent amount of carbon dioxide that would give the same impact. Pound for pound, methane is a much worse greenhouse gas than carbon dioxide, for instance.  While carbon dioxide is written as CO₂, when the greenhouse gases are all lumped together,  the carbon dioxide equivalent is written as CO₂e.

Clearly none of us have totally clean hands in terms of our individual environmental impact. Rather spectacularly, as I look back, in 1996 my husband and I had an unusually long upcoming vacation. Our response was to look for some place that was as far away as possible and had a very different culture from ours. Tonga was our destination. It seemed all good… Back then! Calculating the carbon footprint of that trip now makes it an extremely self-indulgent trip. Now I know that almost all that carbon is still floating around in the atmosphere and will be, probably for centuries.That said, many of us are becoming more aware of individual impacts and that they add up in the aggregate. In a both/and kind of approach I am becoming increasingly excited about working with other people on our individual carbon footprints, as well as attending to the larger political issues. And we can make the individual changes much quicker. Given that approximately 70% of global carbon emissions ultimately occurs because of our individual actions, many individuals joining together could make an enormous difference! Let’s do it TEAM EARTH!

Our Timeline is not endlessly in the future. According to the IPCC, climate scientists have reached a consensus that from the beginning of the industrial revolution in the 1750’s on we have roughly a total carbon budget of 1 trillion metric tons to use before we tip into runaway Climate Change. We have already used about 600 billion metric tons. At our current trajectory we will have used up the rest of our earth budget in 25 years, that is by 2039. Let’s use that as a challenge to become more creative. More flexible. Let’s share ways to enjoy low-carbon adventures. Let’s get to know our neighbors better and create stronger communities, so we can work together on these issues and play together, too.

What carbon footprint numbers should we be targeting? Many of these questions are answered on Shrink That Footprint.

 The following information gives a rough sense of what we, especially those of us in the U.S. need to be thinking about: