0200 GMT October 22, 2019
The Rhodium Group, an independent research group, said emissions rose 3.4 percent in 2018, the biggest jump since 2010, when the economy bounced back from the Great Recession, Reuters reported.
Rhodium said the boost from the world's second-biggest carbon emitter after China could make it harder for the US to meet reductions targets it set under the Paris Agreement in 2015. To do so, the US would have to cut energy-related carbon emissions by 2.6 percent on average over the next seven years, a pace more than twice that achieved between 2005 and 2017.
"It is certainly feasible, but will likely require a fairly significant change in policy in the very near future, and/or favorable market and technological conditions," the group said.
The spike occurred even though 2018 brought a record number of shutdowns of power plants fired by coal, the fuel richest in carbon output when burned.
Natural gas, which emits about half the carbon of coal, replaced most of the lost coal generation. But it also served the vast majority of load growth for electricity last year, the report said.
The Trump administration, which has announced its intent to leave the 2015 Paris Agreement on climate change, is relaxing Obama-era rules on emissions from power plants and vehicles as it seeks to boost production of oil, gas and coal.
The earliest the administration can leave the accord is after the 2020 presidential election.
The US Environmental Protection Agency did not respond to questions about the Rhodium report, saying it would only answer queries related to the partial federal government shutdown or about environmental emergencies.
Trump administration officials have said that emissions can waiver from year to year depending on the economy, but that the country can both cut emissions and enjoy a strong economy at the same time.
Environmentalists say the Trump administration needs to speed up the transition from natural gas to renewables such as wind and solar power and energy storage.
"Coal's sharp-dressed cousin is continuing us on a path to irreparable and costly climate damage," said Greg Cunningham, who works on clean energy and climate at the Conservation Law Foundation.
"It is imperative that we shift our clean energy transition into high gear and accelerate our clean car standards to reverse this trend."
The American Petroleum Institute (API), the top lobbying organization for the US oil and gas industry, said it does not take a position on forming a carbon tax, which some environmentalists, politicians in both parties and petroleum companies say would harness the power of capitalism to reduce emissions. The API backs voluntary efforts to reduce emissions.
Mike Sommers, the head of API, told reporters in a conference call that the US can boost oil and gas and cut emissions at the same time.