There’s a new challenge in the drive to reduce carbon emissions. Efforts in the power sector are apparently succeeding, but now transportation emissions are rising.
In fact, for the first time since 1979, U.S. cars, buses, trucks and airplanes emitted more carbon dioxide than U.S. power plants.
Based on the latest available rolling 12-month average, the electricity sector emitted 1,868 million metric tons (MMt) of carbon dioxide while the transportation sector emitted 1,876 MMt.
For the past 10 years, electricity emissions have been declining due to a number of factors, including growth in renewable energy, level electricity demand, and a shift from coal to natural gas. Since 2005, coal-fired generation has fallen from 50 to 33 percent of the mix, while less carbon-intensive natural gas-fired generation has risen from 19 to 33 percent.
Transportation emissions had been largely flat since the early 2000s, likely due to increasing vehicle efficiency and a combination of social trends (e.g. growing cities, ageing population, increasing telework). But emissions have begun to creep up in the past couple of years.
Some of this uptick can be attributed to much lower oil prices over the past 12 months. But even before oil prices dropped, the total number of vehicle miles traveled was increasing. So, even though our vehicles are getting more fuel efficient over time thanks to corporate average fuel economy (CAFE) standards, the increase in vehicle use is moving emissions in the wrong direction.
Over the long-term, the Energy Information Administration (EIA) projects that transportation emissions will decline as stricter vehicle emission standards come into force for cars and for trucks. As a result of these policies, we expect the adoption rate of vehicles with improved fuel economies, including zero-emission vehicles, will begin to accelerate in the next decade.
At the same time, EIA sees electricity sector emissions continuing to fall, especially as states begin to comply with targets set out in the Environmental Protection Agency’s Clean Power Plan and as the industry responds to other zero-emission incentives like the recently extended renewable tax credits.
Over the next 25 years, the rate of emission decline in the power sector is expected to be greater than in the transportation sector, so it looks like transportation will remain the largest emitting sector for the foreseeable future.
The good news is that carbon dioxide emissions will be declining in the two largest emitting sectors, due in part to strong policies to encourage a low-carbon future.
However, it’s also clear that additional policies and actions will be required for all economic sectors to see larger emissions reductions, which scientists say are necessary by mid-century in order to avoid the worst effects of climate change.