Even as the world’s economy grew by more than 3% from 2013 to 2015, global carbon dioxide emissions from fossil-fuel combustion were flat for the second year in a row. Worldwide energy-related emissions of CO 2 were 32.1 billion tons in 2015, essentially unchanged from their 2013 level, according to preliminary data released March 16 by the International Energy Agency (IEA).

The IEA data suggest that renewable energy production played a major role in the decoupling of CO 2 from economic growth. Wind, solar, and hydroelectric power accounted for about 90% of new electricity generation in 2015; wind alone produced more than half of new electricity generation.

(Image credit: © OECD/IEA 2016, IEA Publishing. License.)

Both of the two largest energy-related CO 2 emitters, China and the US, experienced a decline in 2015, the IEA data release said. Decreasing coal use in China resulted in a 1.5% reduction in emissions from 2014. Economic restructuring toward less energy-intensive industries and the government’s efforts to decarbonize electricity generation pushed coal use down. In 2015, coal generated less than 70% of Chinese electricity, 10 percentage points less than in 2011. Over the same period, low-carbon sources jumped from 19% to 28%, with hydro and wind accounting for most of the increase.

In the US, emissions declined 2% last year as electricity generation from natural gas continued to replace coal. Emissions rose in most of the developing countries in Asia as well as in Europe. Since 1975, when the IEA started providing information on CO 2 emissions, there have been only four periods in which emissions remained the same or decreased compared with those of the previous year. Three of those periods—the early 1980s, 1992, and 2009—were associated with global economic weakness.

The US Energy Information Administration (EIA) estimates that from 2014 to 2015 US energy-related CO 2 emissions declined 2.4%, from 5.4 billion tons to 5.3 billion tons. The EIA estimates a further decline of 0.3% this year, followed by an increase of 0.4% in 2017.