The US isn't faring well in efforts to keep carbon dioxide emissions in check. Rhodium Group analysts have determined that CO2 emissions jumped 3.4 percent year-over-year in 2018, or the largest increase since 2010. The reasons for the worsening output aren't necessarily what you expect, though. The research team attributed it both to a cold winter (thus increasing the use of oil and gas for heat) and, more importantly, a then-booming economy. The growth led to greater uses of factories, aircraft and trucks that frequently aren't subject to strict environmental policies, leading to sharp upticks in emissions. Industry alone saw emissions climb by 5.7 percent.