U.S. greenhouse gases inched lower in 2017, with transportation continuing its reign as the leading source of emissions, new EPA data showed.

Greenhouse gases dipped 0.3 percent from 2016 to 2017, the Environmental Protection Agency found in its latest annual greenhouse gas inventory. The agency released the draft of new inventory, which looks at greenhouse gas emissions in the U.S. from 1990 to 2017, for public comment Feb. 12.

The dip in emissions resulted largely from the continued move toward cleaner burning fuels—such as natural gas and renewable energy—to produce electricity, and away from carbon-intensive coal, the report said.

But the drop in emissions isn’t as large as prior years’ emissions cuts. For example, greenhouse gas emissions nationwide declined nearly 2 percent between 2015 and 2016, according to the EPA’s prior inventory, released in April 2018.

The smaller decline in 2017 could signal a departure from the downward trend in U.S. emissions. The Rhodium Group, an independent provider of research, estimated in a January report that U.S. emissions in 2018 increased by more than 3 percent.

EPA air chief Bill Wehrum, however, dismissed concerns that emissions were dropping at a slower rate.

He referenced emissions cuts in the power sector driven in large part by market forces such as low-cost natural gas.

The power sector has “been a great success story the last few years largely because of the shift from coal to natural gas,” Wehrum told reporters Feb. 12 on the sidelines of the National Association of Regulatory Utility Commissioners winter policy meeting in Washington.

“That’s had some detrimental effects on certain aspects of the industry, but from a greenhouse gas emissions standpoint, it’s resulted in significant and steady emissions reductions from that sector,” Wehrum added.

‘Barely in the Noise’

Critics say it isn’t enough to rely on market forces to cut emissions.

The EPA’s inventory shows U.S. emissions are continuing to drop, but the annual dips are microscopic compared to what is needed to stay on track to meet global climate goals, Joseph Goffman, former senior counsel in the EPA’s air office during the Obama administration, told Bloomberg Environment.

“The year-to-year changes are just barely even in the noise,” Goffman, now executive director at Harvard University’s Environmental and Energy Law Program, said. “This is what the current commitment to inaction looks like.”

The Trump EPA is also pushing policies that would try to reverse or hinder market forces leading the power sector away from coal, Goffman added, citing the EPA’s plans to replace Obama-era carbon controls for existing power plants.

Transportation Sector

Goffman also noted in other sectors, such as the transportation and industrial sectors, market forces are pushing emissions increases instead of decline.

“In the transportation sector, market forces are diametrically opposed to accomplishing the kind of results that we need to accomplish in terms of climate change,” Goffman said.

The EPA report found that transportation again topped the electric power sector in 2017 in emitting greenhouse gases, accounting for 36.5 percent of the total from fossil fuel combustion. Electricity generation, by comparison, accounted for 35 percent, the EPA report said.

The EPA will take public comment on the inventory through March 14, and will publish the final version in April.