Dramatic increase in ecosystem respiration causes record-breaking atmospheric CO<sub>2</sub> growth rate in 2024.

Dong, Guanyu; Jiang, Fei; Ju, Weimin; Peñuelas, Josep; Ciais, Philippe; Zhang, Yongguang; Xiao, Jingfeng; Wang, Xuhui et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

2024 is the hottest year on record, accompanied by extreme precipitation, droughts and fires. The global atmospheric CO<sub>2</sub> growth rate in 2024 reached a historic high of 3.73 ppm yr<sup>-1</sup>, significantly surpassing the previous record set during the 2015/16 El Niño event. Here, we investigate the causes and underlying mechanisms of this record-high growth rate by combining satellite-based atmospheric inversions and estimates of gross primary production and fire emissions. We find that the record-high CO<sub>2</sub> growth rate is due to large reductions in the land CO<sub>2</sub> sink. This is dominated by a dramatic increase in total ecosystem respiration, which occurred primarily in grass and shrub lands, owing to compound hot-wet climatic conditions in 2024. Given the projected increase in the frequency and intensity of compound pluvial-hot extremes under warming, changes in ecosystem respiration will become more drastic and cause positive feedback to climate warming.