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Climate change. We all might have heard of this or maybe not.
Climate change is a large-scale, long-term shift in the planet's weather patterns or average temperatures which leads to global warming. Transportation is one of the main cause of climate change. Globally, about 15% of manmade carbon dioxide comes from cars, trucks, airplanes, ships, and other vehicles. Cars, trucks and sport utility vehicles driven by citizens are to blame for about two-thirds of greenhouse gas emissions from the Canadian transportation sector. As more passenger vehicles hit the roads, this pollution will increase dramatically unless strict emissions-reduction and fuel economy policies are in place.
When emissions from electricity are distributed to economic sectors, industry accounts for the largest share of U.S. greenhouse gas emissions (nearly 29 percent), followed closely by emissions from transportation activities (28 percent of total emissions). The commercial and residential sectors are also responsible for a substantial portion of emissions, each responsible for 17 percent of the total when emissions from electricity are distributed, due to their relatively large share of electricity consumption.
Since 1990, transportation has been one of the fastest-growing sources of U.S. GHGs. In fact, the rise in transportation emissions represents 48 percent of the increase in total U.S. greenhouse gases since 1990.
The largest sources of transportation GHGs in 2006 were passenger cars (34%) and light duty trucks, which include sport utility vehicles, pickup trucks, and minivans (28%). Together with motorcycles, these light-duty vehicles made up about 63% of transportation GHG emissions. The next largest sources were freight trucks (20%) and commercial aircraft (7%), along with other non-road sources (which combined, totaled about 7%). These figures include direct emissions from fossil fuel combustion, as well as HFC emissions from mobile air conditioners and refrigerated transport allocated to these vehicle types.
It is important to note that fuel consumed in international travel by aircraft and marine sources is not counted in national greenhouse gas inventories. However, international trade has been growing rapidly, thus increasing the role of transportation as a source of global emissions.
Aircraft can have some unique and complex effects on the atmosphere due to the release of emissions and water vapor at high altitude. For instance, jet aircraft create condensation trails, or contrails, at cruise altitude in the upper atmosphere due to the combination of water vapor in aircraft engine exhausts and the low ambient temperatures that often exist at these high altitudes. Contrails affect the cloudiness of the earth's atmosphere, and therefore might affect atmospheric temperature and climate.
Useful sources:
https://www.sciencedaily.com/releases/2008/03/080311120617.htm
http://www.sciencedirect.com/science/article/pii/S136192090800165X
http://www.biologicaldiversity.org/programs/climate_law_institute/transportation_and_global_warming/
