Carbon dioxide emissions from energy generation continued a decline worldwide in 2015, despite a growing global economy, says a report by the International Energy Agency. Last year marked only the fourth time in 40 years that CO2 emissions have declined for two years running from the energy sector, the largest source of human-generated greenhouse gas emissions. Past declines were due to a weak economy, according to IEA. But the global economy grew by 3.1% last year and 3.4% in 2014, which, IEA says, offers evidence that the link between economic growth and emissions growth is weakening. Agency data suggest that recent CO2 reduction was spurred by growth in renewable energy, which accounted for 90% of new electricity generation in 2015 . Wind alone produced more than half of new electricity generation. The world’s two largest CO2 emitters, China and the U.S., declined in energy-related CO2 releases in 2015. Chinese emissions fell 1.5%, as coal use dropped for the second year in a row. U.S. emissions declined by 2%, driven by a switch from coal to natural gas for electricity generation.