A couple of weeks ago, Mike and I took a road-trip down to Worcester MA to take a holiday, visit some friends, and attend Readercon (the latter was just me, Mike went to Walden Pond instead). As we are a car-free household, we rented a car for the trip–making sure to get the smallest, most fuel-efficient car they could provide us with.
To calculate the greenhouse gas emissions for the 1636 kms we drove over the 5-day period I consulted a couple of websites. First, to determine the fuel-efficiency of the vehicle we rented I went to the handy site that the US government runs: www.fueleconomy.gov. According to this site, our rental car had a fuel-economy of 26 miles per gallon on highways (and our driving was mostly highway driving).
Taking this information I then went to the US/Swiss-based non-profit Sustainable Travel International. Using their handy travel calculator our emissions came out to 0.346 tons of CO2. For $5.28 US, I was able to offset these emissions through donating to projects that have been verified to reduce the global GHG load, primarily through supporting renewable energy production.
I would have liked to use a Canadian organization to offset my GHG emissions but was unable to find one that works with individual consumers (I consulted the Ecobusiness directory). If anyone knows of one please comment.