Drive electric
Each kilometre driven in a petrol or diesel fuelled car emits 150 grams of CO2 directly into the atmosphere, and directly contributes to your personal carbon footprint. Hybrids fare a little better at 56 grams per kilometre. A fully electric vehicle emits no CO2 when driven.
Electric vehicles are becoming more and more affordable, and are supported by tax breaks and other incentives in many countries. By switching from a petrol/diesel car to electric, you can greatly reduce your carbon footprint sourced from transport.
If a brand new electric vehicle is out of reach, be sure to check out the second hand market, or consider leasing until the price of a new electric vehicle falls enough to become an option.