U.S. greenhouse gas emissions roared back in 2021, the latest indicator that the country remains far off track from meeting President Biden’s ambitious climate change targets for the end of this decade.

A 17 percent surge in coal-fired electricity helped drive an overall increase of 6.2 percent in greenhouse gas emissions compared with the previous year, according to an analysis published Monday by the Rhodium Group. While emissions remained below pre-pandemic levels, it marked the first annual increase in reliance on the nation’s dirtiest fossil fuel since 2014, the independent research firm said.

The rise in the nation’s emissions, which many experts anticipate will continue this year, is a sign of an economy on the mend. But it also signals a potentially ominous climate reality: The United States is not yet emerging from the coronavirus pandemic with a greener economy, making it that much harder for Biden to deliver on his pledge to cut the nation’s emissions in half by 2030.

“In an ideal world, we want the economy to rebound, but not the emissions,” Kate Larsen, a co-author of the analysis who leads Rhodium’s international energy and climate research, said in an interview.

Larsen added that the surge in coal generation was “almost entirely due to high natural gas prices” as oil and gas producers curbed new production in response to lower global demand because of pandemic lockdowns. “Emissions from our power sector were pretty much at the whim of energy markets,” she said.

The nation’s largest source of greenhouse gas emissions — transportation — also saw the steepest rebound during 2021, rising 10 percent over the previous year, Rhodium found. The arrival of coronavirus vaccines and the nation’s fitful efforts to emerge from the pandemic meant more Americans traveled on roads and in the skies than in 2020. But road freight was the only mode of transportation that rebounded to pre-pandemic levels, as thousands of diesel-powered trucks rumbled along the nation’s highways to deliver consumer goods.

Last spring, Biden vowed to launch an all-of-government effort to cut U.S. carbon pollution 50 to 52 percent by 2030, compared with 2005 levels, and to put the nation on track to reach net-zero emissions by 2050.

“We’re going to cut U.S. greenhouse gas emissions by well over a gigaton by 2030, while making it more affordable for consumers to save on their own energy bills with tax credits for things like installing solar panels, weatherizing their homes, lowering energy prices,” Biden told fellow world leaders at a United Nations climate summit in Glasgow, Scotland, in November.

He promised to electrify school bus fleets, increase tax credits for electric vehicles, ramp up construction of solar panels and wind turbines and incentivize cleaner manufacturing — all while creating well-paying union jobs.

“We’ll demonstrate to the world the United States is not only back at the table but hopefully leading by the power of our example,” he said.