Your airline miles may be your largest climate impact, so until biodiesel planes take flight, offset your miles at carboncounter.org. For example, a trip from PDX-JFK generates 1,900 lbs of CO2, while a flight to London generates a whopping 3,821 lbs of CO2. Write your yearly miles in the renewable energy section of our book or on a piece of reused scrap paper, then work to offset them.