Everything is the real problem. If we eliminated everything but transportation, we'd still be screwed. Transportation, agriculture, manufacturing, domestic energy use - we have to fix it all to stand any hope of mitigating the worst effects of climate change. We can fix it all, but that requires concerted effort.
Transportation is the biggest single source of emissions in the US, so it is entirely reasonable to make it a high-priority target.
Transportation is the biggest single source of emissions in the US, so it is entirely reasonable to make it a high-priority target.
https://www.ipcc.ch/sr15/
https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...