1  Mobile combustion

1.1 Introduction

Transportation emissions, when grouped together, are one of the largest sources of greenhouse gas emissions nationally, statewide, and locally.

This is the transportation section for estimating on-road emissions. Modes included are motorcycles, passenger cars, intercity buses, light commercial trucks, single unit long-haul trucks, refuse trucks, single unit short-haul trucks, transit buses and school buses. Aviation data provided are considered preliminary at this time.

Note that this does not include freight rail, light rail, and other transportation emissions.

1.2 2022 emissions

Transportation emissions totaled 16.58 MMtCO₂e, accounting for 35% of regional emissions in 2022.

Figure 1.1: 2022 transportation emissions by county

We can also view this data broken out by vehicle weight in Figure 1.2.

Figure 1.2: 2022 annual emissions by vehicle weight

We can also view this data broken out by fuel type.

Figure 1.3: 2022 annual emissions transportation by fuel type

Lower population counties have high transportation emissions per person. These counties also have higher emissions from trucks than the higher population counties.

Figure 1.4: 2022 transportation emissions per capita by county

1.3 Historical emissions

Despite a 10.3% reduction in the transportation sector due to the Covid pandemic, emissions in this sector rebounded in 2022.

Figure 1.5: Transportation emissions, 2002-2022

1.4 Forecasted emissions

Despite expected increases in vehicle miles traveled, generally, emissions are expected to decrease over time due to improvements in fuel efficiency and changes in vehicle fuel types. We supply outputs from our Regional Travel Demand Model (RTDM) to EPA MOVES4 to create these estimates.

Figure 1.6: Transportation emissions forecast, 2022-2050