Yesterday I calculated my carbon footprint and then made a donation to The Nature Conservancy that ‘offset’ my greenhouse gases for this year.
Unfortunately, offsetting emissions is not a solution to the environmental issues resulting from our lifestyles and consumption patterns: only decreasing actual emissions does this. However, where emissions are unavoidable, offsetting (with a reputable organisation) is better than doing nothing.
Carbon footprint calculators are plentiful on the internet. I used: http://www.nature.org/greenliving/carboncalculator.