Energy-related carbon dioxide emissions plateaued in 2019

Global energy-related emissions of carbon dioxide last year stayed even with 2018 levels, even as the world economy expanded by nearly 3%, according to data released by the International Energy Agency (IEA) on 11 February. The plateauing was mainly the result of declining coal use for power generation and unusually mild weather in major energy-consuming nations, the nongovernmental organization said.

The news that global emissions from energy production were unchanged at about 33.3 billion metric tons (Gt) led IEA executive director Fatih Birol to express hope that global CO₂ output may have peaked for good. But the IEA’s own data show that peaks have occurred before, most recently in 2014, only to be followed soon after by renewed climbing.

Energy-related emissions from advanced economies decreased by 370 Mt (3.2%) from 2018. The US had the largest absolute reduction (140 Mt, or 2.9%) of any country, while the European Union and Japan cut larger shares of their emissions: 5% and 4.3%, respectively. The 4.8 Gt spewed by the US last year is nearly 1 Gt below its peak emissions in 2000. (The IEA classifies as advanced economies Australia, Canada, Chile, European Union, Iceland, Israel, Japan, Mexico, Norway, New Zealand, South Korea, Switzerland, Turkey, and the US.)

But emissions outside the advanced economies grew by nearly 400 Mt in 2019, with 80% of the increase occurring in Asia. Coal, which accounts for 50% of energy use in that region, continued to expand, but energy demand was tempered in China and India by slower economic growth.

Coal-fired power generation in the US fell by 15% in 2019 compared with 2018. Switching to natural gas picked up speed as natural gas prices plunged by 45%. Gas emits only about half as much CO₂ as coal per unit of energy. As with many of the large economies, mild weather slowed US energy consumption for heating and cooling last year. Emissions in the advanced economies are now at their lowest levels since the late 1980s, even as electricity demand has grown by one-third.

In an 11 February statement , US Energy secretary Dan Brouillette attributed the global emissions flattening to “nations that have successfully deployed carbon capture, renewable energy, natural gas, and nuclear power.” Nearly all the CO₂ that is captured from fossil-fuel production and combustion today is used for enhanced oil recovery. Most of the CO₂ used in that process remains underground, but its capture is offset by the emissions from the petroleum it forces out of the ground. As of last year, there were only five facilities built not for oil recovery but specifically to capture and permanently store CO₂ underground. The largest, in Australia, plans to sequester up to 4 Mt annually.

The IEA estimates are more optimistic than projections made in early December by the Global Carbon Project (GCP). The academic collaboration estimated a small increase in CO₂ emissions from fossil-fuel sources after adjusting for cement production, which the IEA didn’t include in its tally. Cement accounts for 3–‍8% of global CO₂ output.

Rob Jackson, an Earth system scientist at Stanford University who chairs the GCP, says the discrepancy between the groups’ numbers is due mainly to the IEA’s considerably larger estimated reductions for the US and the European Union. Jackson says the differences will become clearer once the IEA releases its full data set in a month or so.

The IEA figures do not include CO₂ emissions from agriculture; changes in land use, such as burning and clearing; or other industrial processes, such as ammonia production. Collectively, those sources account for around 21% of total greenhouse gas emissions.