Choosing to walk instead of driving or taking a lift could save around 0.59 kg CO2 per day (see here for full calculation and assumptions).
The CO2 values in the slider have been averaged over a month, and split equally over the four data points, calculated as follows:
Q. How often do you walk instead of taking the car?
Endpoints:
Never walk, always drive - 0 kg
Always walk - (0.59) x (7 days) x (4 weeks) = 16.52 kg CO2
Midpoints:
Walk a bit - (16.52) x (1/3) = 5.51 kg CO2
Walk a lot - (16.52) x (2/3) = 11.01 kg CO2
