Environmental Pollution Scenario: Review and Summary Although cities contribute to both waste and global warming because of population density and the demands of urban life, they also offer the potential to conserve energy in terms of transportation costs, in comparison to suburban and rural areas. The compact nature of cities makes alternative transportation such as buses, subways, walking, jogging, and bicycle use a feasible alternative to using cars. Regarding the effectiveness of public transportation, in terms of mitigating the effects of global warming it is estimated that "public transit reduces carbon monoxide emissions by nearly 745,000 tons annually. This equals nearly 75% of the carbon monoxide emissions by all chemical manufacturers in the United States" (How public transportation helps the environment, 2014). Public transportation also reduces smog-generating pollutants by 100,000 tons per year (How public transportation helps the environment, 2014).

Finally, using public transportation reduces U.S. dependency on oil in a meaningful fashion: "public transportation in the U.S. saves 1.4 billion gallons of gasoline every year -- about equal to 300,000 cars filling up every day" (How public transportation helps the environment, 2014). From the point-of-view of commuters, using public transportation is of personal benefit. It allows them to avoid traffic jams, to work on the train or bus rather than paying attention to the road, and by taking cars off the road, it makes the commute far more pleasant and ambient for all concerned. Cities can incentivize public transportation by providing affordable...

Although it is costly to build a public transportation system and to maintain it, the cost savings in the long-term outweigh the potential negatives.
Another valuable source of alternative transportation is bicycling. Unlike public transportation, which merely reduces the carbon footprint of the commuter, bicycling is a completely sustainable and renewable source of energy in the form of human effort alone. It also has the advantage of providing exercise to users: instead of burning calories in a gym which requires air-conditioning and electricity, commuters can easily fit more movement into their busy lives through cycling. Many cities around the world including Amsterdam, make bicycling a vital part of the city's culture. "Small changes to infrastructure can make a big difference for commuter cyclists. Copenhagen has introduced new foot rests to help you catch your breath at the lights, and two-wheelers in London can now signal that they are waiting for the green bike by pressing a button" (Tackling congestion in cities by encouraging cycling. 2014, thisbigcity).

However, there are some inevitable obstacles in encouraging cycling: putting in more bicycle lanes can be controversial because car drivers resent having to share the road with cyclists: even many pedestrians are angry when cyclists refuse to share the roads with them or come onto the sidewalks, nearly running them over when space is at a premium. There also are…