For the first time in 40 years, emissions data indicates that the largest source of greenhouse gas pollution in the US comes from transportation. The previous heavyweight was electricity production, but now planes, trains, and automobiles (to name a few) have taken the lead.
This isn't necessarily bad news. The change comes as US electricity generation relies less on fossil fuels and more on renewables and cheap natural gas.
But the automotive sector is lagging behind. More than 50 percent of urban pollution can be attributed to motor vehicles. The US Energy Information Administration indicates that carbon dioxide emissions emitted in 2016 by transportation increased by 1.9 percent, overtaking power generation as the most polluting sector in the country. Motor gasoline made up 56 percent of that net increase.
With an average vehicle age of 11.5 years on American highways, experts say it is likely to stay that way until more new, fuel efficient vehicles are on the roads. Currently, a typical gasoline car emits 9 kilograms (20 pounds) of carbon dioxide for each gallon of gasoline burned.
Despite US fuel standards set forth by the 1970 Clean Air Act, lower-than-average gas prices mean more people are on the roads and in the skies. US aircrafts alone account for 30 percent of CO2 emissions from global aviation.
So where does that put the US?
The Trump administration plans to reverse curbs on auto industry pollution and review regulations that would set tougher emission standards for car and truck companies. This is despite the fact that the US is currently one of the larger CO2 emitters, ringing in at 16.5 metric tons per capita. Compare that with the 45.4 metric tons produced by Qatar (highest) or the United Kingdom's 6.5 metric tons.
Early estimates from the Global Carbon Project, a group of international researchers, project a worldwide rise in CO2 emissions of about 2 percent in 2017.
It is no secret climate-warming emissions adversely affect health, and the risk is much greater for the almost 45 million Americans who live, work, or attend schools near transportation areas with high air pollution levels.
However, it may take some time for American habits to catch up with technological innovations. A recent study suggests it may take until 2040 to have up to 90 percent of vehicles electric.
Can't shell out for a new car? A bicycle isn't the only eco-friendly alternative. A person with a 32-kilometer (20-mile) round trip commute can reduce their carbon emissions by almost 5,000 pounds a year by taking public transportation.
Want to know how your commute is contributing to transportation emissions? Calculate your carbon footprint here.