America’s carbon-dioxide emissions rose by 3.4 percent in 2018—the biggest increase in eight years. The estimate, by the research firm Rhodium Group, suggests the country’s recent progress on reducing carbon emissions has now been put in reverse, The New York Times reports. U.S. fossil-fuel emissions had fallen significantly since 2005 and declined in each of the last three years. The rise in 2018 came despite a near-record number of coal plants being retired last year. Some of the increase was attributed to a cold winter that led to more oil and gas being used for heating in some areas of the country, while the economy grew at a strong pace, meaning that emissions from factories, planes, and trucks also increased. Emissions from industrial sectors such as steel, cement, chemicals, and refineries increased by nearly 6 percent. “The big takeaway for me is that we haven’t yet successfully decoupled U.S. emissions growth from economic growth,” said Trevor Houser, a climate and energy analyst at the Rhodium Group. However, carbon-dioxide emissions are still down 11 percent since 2005.