Transportation accounts for about 30% of GHG emissions in the United States, and more than half of that comes from passenger vehicles. Decarbonizing transportation is as challenging as decarbonizing electricity, but in different ways. Essentially, vehicles from aircraft to automobiles that currently run on liquid fossil fuels will have to find another power source that doesn’t emit GHG. Unlike stationary electrical power plants, vehicles are mobile and thus require zero carbon power sources that are robust, light weight, portable, and quickly renewed or refilled. The current choices are electrically-powered vehicles that run on rechargeable batteries, and internal combustion engines that use liquid or gaseous biofuels with carbon-neutral emissions. Advanced vehicle options include hydrogen-powered chemical fuel cells as electrical power sources, and hydrogen is also being considered as a non-carbon fuel for internal combustion engines. Mass transportation can be decarbonized through initiatives like trains powered by net zero electricity and cities that reduce automobile use by being more pedestrian and bicycle-friendly. As with most things in life, none of these are perfect and they all have their advantages and disadvantages. Given the potential severity of the climate crisis, however, an “all of the above” strategy for decarbonizing vehicles is warranted.