Pace of CO2 Gain in Earth's Atmosphere Picks Up

The pace at which the concentration of carbon dioxide in the Earth’s atmosphere is increasing picked up in May 2025, fully reversing the downward trend that began after December 2024.

The latter half of 2024 had seen record high levels of CO₂ accumulation in the Earth’s air thanks largely to efforts by Chinese firms to produce and export as many goods as they could ahead of new tariffs and trade restrictions that were expected to be imposed on China-produced goods. Industrial production slumped in China following its efforts to front-run (or front-load) their exports before these anti-free trade measures were implemented. Since China is by far and away the world’s biggest producer of carbon dioxide emissions, changes in its economic output directly affect the rate at which the concentration of CO₂ changes.

From January 2025 through March 2025, the rate of CO₂ accumulation fell, before stalling in April. The data for May 2025 however shows it rose, which suggests a new effort to stimulate China’s economy began in early April. This timing coincides with President Trump’s “Liberation Day” tariff announcement, which saw the U.S.’ highest tariff rates applied to goods produced in China, which then escalated even higher as China imposed retaliatory tariffs on U.S.-produced goods and the U.S. responded in kind.

The following chart, which tracks the trailing twelve month average of the year-over-year change in the rate at which the concentration of carbon dioxide measured at the remote Mauna Loa Observatory has changed from January 2000 through May 2025, shows the reversal:

The January-March 2025 downturn also coincides with a quarter of negative real economic growth in the U.S., which was highly influenced by the frontrunning (or front-loading) of exports to the United States following their production in China in 2024.

On the stimulus side of the story, there are several developments that indicate unusual interventions by China’s government is behind the increase in CO₂. First, China’s government has approved new coal-fired power plants:

China approved 11.29 gigawatts (GW) of new coal power capacity in the first quarter of 2025, Greenpeace’s review of official documents showed. This pace of coal-fired electricity approvals already exceeds the 10 GW China approved in the first half of 2024.

Second, China’s coal-fired power plant managers have been directed to buy more coal, even though China’s economy has slowed and its demand wouldn’t support it unless part of a larger stimulus effort:

China is pressing its coal-fired power plants to stockpile more of the fuel and import less in an effort to shore up domestic prices, sources with knowledge of the matter said, but traders are sceptical the measures will help to stop the slide.

The coal industry in China faces rising stockpiles of the fuel after a massive expansion of output following shortages and blackouts in 2021 is churning out more coal than even the world’s largest thermal power fleet can consume.

To support miners whose profits are under pressure, the state planner has asked power plants to prioritise domestic coal and increase thermal coal stockpiles by 10%, setting an overall target of 215 million metric tons by June 10, the sources said.

Third, China announced earlier it will build additional coal-fired power generation capacity to compensate for gaps in the reliability of power produced by renewable energy sources. The announcement will see China continue producing coal-fired power plants through 2027 and represents a significant stimulus initiative.

On that final count, the world had a wake-up call from the collapse of Spain and Portugual’s electricity grid on 28 April 2025, which was caused by unstable solar energy production and ensured by the absence of more reliable conventional fossil-fuel or nuclear-based power generation. China’s government is backing increased coal-fired electricity production as a solution to this problem in the near term.

References

National Oceanographic and Atmospheric Administration. Earth System Research Laboratory. Mauna Loa Observatory CO2 Data. [Online Data]. Updated 5 June 2025.

Image credit: Shuozhou coal power plant in Shuozhou, Shanxi, China by Kleinolive on Wikimedia Commons. Creative Commons CC by-SA 3.0 Attribution 3.0 Unported Deed.