Chris asked:
What is the carbon footprint of a bicycle? Am I better off taking the bus or my bike? (for long vs short distances)
I replied:
First, you’d want to look at your whole footprint… not just carbon. Carbon dioxide is just one pollution problem carbon monoxide, which causes ozone pollution, is also very important.
The EPA lists these six:
carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride
(see http://worldcitizen.net/green/2009/04/17/epa-greenhouse-gases-pose-threat-to-public-health/)
In any event, I think the bike would win over the bus in all instances for “carbon footprint” size.
Even if the bus was full of people, the economies of scale would only put a small dent in the environmental costs of motor vehicles.
Besides the energy used to run the bus, you would want to also consider the energy and material to build the bus, replace tires and build the roads, etc.
A bus is hard on the roads. If everyone road bikes, the bike trails would reduce a huge amount of asphalt. Not only would this reduce the carbon footprint, it would reduce the problems of impervious surface.
Besides direct health risks, the EPA also considered these:
increased drought;
more heavy downpours and flooding;
more frequent and intense heat waves and wildfires;
greater sea level rise;
more intense storms; and
harm to water resources, agriculture, wildlife and ecosystems.
I’ll ask others what they think, too.