section_path: Impact/Environment
section_name: Environment
paragraph_text: Environment
  
  Global greenhouse gas emissions from transportation:
  
  Transport is a major use of energy and burns most of the world's petroleum. This creates air pollution, including nitrous oxides and particulates, and is a significant contributor to global warming through emission of carbon dioxide, for which transport is the fastest-growing emission sector. By sub-sector, road transport is the largest contributor to global warming. Environmental regulations in developed countries have reduced individual vehicles' emissions; however, this has been offset by increases in the numbers of vehicles and in the use of each vehicle. Some pathways to reduce the carbon emissions of road vehicles considerably have been studied. Energy use and emissions vary largely between modes, causing environmentalists to call for a transition from air and road to rail and human-powered transport, as well as increased transport electrification and energy efficiency.
  
  Other environmental impacts of transport systems include traffic congestion and automobile-oriented urban sprawl, which can consume natural habitat and agricultural lands. By reducing transport emissions globally, it is predicted that there will be significant positive effects on Earth's air quality, acid rain, smog, and climate change.
  
  While electric cars are being built to cut down CO emission at the point of use, an approach that is becoming popular among cities worldwide is to prioritize public transport, bicycles, and pedestrian movement. Redirecting vehicle movement to create 20-minute neighbourhoods that promotes exercise while greatly reducing vehicle dependency and pollution. Some policies are levying a congestion charge to cars for travelling within congested areas during peak time.
  
  Airplane emissions change depending on the flight distance. It takes a lot of energy to take off and land, so longer flights are more efficient per mile traveled. However, longer flights naturally use more fuel in total. Short flights produce the most CO per passenger mile, while long flights produce slightly less. Things get worse when planes fly high in the atmosphere. Their emissions trap much more heat than those released at ground level. This isn't just because of CO, but a mix of other greenhouse gases in the exhaust. City buses produce about 0.3 kg of CO for every mile traveled per passenger. For long-distance bus trips (over 20 miles), that pollution drops to about 0.08 kg of CO per passenger mile. On average, commuter trains produce around 0.17 kg of CO for each mile traveled per passenger. Long-distance trains are slightly higher at about 0.19 kg of CO per passenger mile. The fleet emission average for delivery vans, trucks and big rigs is 10.17 kg (22.4 lb) CO per gallon of diesel consumed. Delivery vans and trucks average about 7.8 mpg (or 1.3 kg of CO per mile) while big rigs average about 5.3 mpg (or 1.92 kg of CO per mile).