How much pollution is caused by transportation?

Greenhouse gases. In fact, tailpipe emissions from cars, trucks and buses account for over one-fifth of the United States' total global warming pollution; transportation, which includes airplanes, trains, and ships accounts for around thirty percent of all heat-trapping gas emissions.



As of early 2026, the transportation sector remains one of the largest contributors to global environmental degradation, accounting for approximately 13.7% to 15% of all global greenhouse gas emissions. Road travel (cars, trucks, and buses) is responsible for the lion's share of this impact, contributing about 75% of total transport-related carbon emissions. While the rapid adoption of electric vehicles (EVs) in major markets like China and the EU has begun to "bend the curve" of tailpipe CO2, aviation and shipping remain difficult-to-decarbonize sectors. Beyond CO2, transportation is a primary source of nitrogen oxides (NOx​) and particulate matter (PM2.5​), which contribute to millions of premature deaths annually from respiratory and cardiovascular diseases linked to poor urban air quality.

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In fact, unless you're looking to venture from Los Altos to LA off-road through state parks the whole way—in a Hummer with Tonka-truck mud tires—driving is generally greener than flying.

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Public transportation gets people where they're going while emitting far fewer climate-warming greenhouse gases than private cars. The reason is simple efficiency: while cars usually carry just one or two people at a time, a bus can carry 50 or more, and a train in a large city may carry thousands.

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For the shortest trip, driving is slightly more economical than flying. But for the longer cross-country trip, flying is far cheaper. And keep in mind that this only considers solo drivers. Families or friends traveling in one vehicle can save money by driving, even on longer routes.

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Walk, bike or take the train for the lowest footprint Using a bike instead of a car for short trips would reduce your travel emissions by around 75%. If you can't walk or cycle, then public transport is usually your best option. Trains are particularly low-carbon ways to travel.

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