If governmental attention and dire pronouncement by the scientific community are any indication, global warming is the greatest single threat to planetary survival.
And seeing how the hundreds of millions of cars on our roads are spewing out greenhouse gases with every inch they drive, cutting back on cars in favor of zero-emitting bicycles would be a tremendous improvement in the global-warming outlook. It wouldn't even require an all-or-nothing approach: If everyone in the world who works less than 5 miles (8 kilometers) from home cycled instead of driving to work one day a week, it would reduce greenhouse-gas emissions by 5 million tons (4.5 metric tones) a year [source: UCF]. That's the equivalent of 1 million people getting rid of their cars [source: UCF].
But it's not just about greenhouse gasses. It's about using less and wasting less. Someone riding a bike can go 960 miles (1,600 kilometers) on the amount of energy that goes into moving a car about 20 miles (32 kilometers) [source: Hood]. Overall, a commuting cyclist has about one-tenth the ecological footprint of a commuting driver [source: UCF].
It's really just part of an overall more sustainable lifestyle that could end up saving the planet.
For more information on cycles, saving the planet and related topics, look over the links on the next page.