Human mobilization and use of reactive nitrogen (Nr) has been one of the major aspects of global change over the past century. Nowhere has that change been more dramatic than in China, where annual net Nr creation increased from 9.2 to 56 Tg from 1910 to 2010. Since 1956, anthropogenic Nr creation exceeded natural Nr creation, contributing over 80% of total Nr until 2010. There is great interest and uncertainty in the fate and effects of this Nr in China. Here, a comprehensive inventory of Nr in China shows that Nr (including recycled Nr) has continuously and increasingly accumulated on land (from 17 to 45 Tg), accompanied by increasing transfers to the atmosphere (before deposition; from 7.6 to 20 Tg), inland waters (from 2.7 to 9.6 Tg), and coastal waters (from 4.5 to 7.7 Tg) over the past 30 y. If current trends continue, Nr creation from human activities will increase to 63 Tg by 2050, raising concerns about deleterious environmental consequences for land, air, and water at regional and global scales. Tremendous amounts of Nr have accumulated in plants, soils, and waters in China over the past 30 y, but the retention capacity of the terrestrial landscape seems to be declining. There is a possibility that the negative environmental effects of excessive Nr may accelerate in coming decades, increasing the urgency to alter the trajectory of increasing Nr imbalance. Here, a conceptual framework of the relationships between human drivers and Nr cycling in China is oriented and well-targeted to Chinese abatement strategies for Nr environmental impact.

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China is mobilizing the largest anthropogenic reactive nitrogen (Nr) in the world due to agricultural, industrial and urban development. However, the climate effects related to Nr in China remain largely unclear. Here we comprehensively estimate that the net climate effects of Nr are −100 ± 414 and 322 ± 163 Tg CO2e on a GTP20 and a GTP100 basis, respectively. Agriculture contributes to warming at 187 ± 108 and 186 ± 56 Tg CO2e on a 20-y and 100-y basis, respectively, dominated by long-lived nitrous oxide (N2O) from fertilized soils. On a 20-y basis, industry contributes to cooling at −287 ± 306 Tg CO2e, largely owing to emissions of nitrogen oxides (NOx) altering tropospheric ozone, methane and aerosol concentrations. However, these effects are short-lived. The effect of industry converts to warming at 136 ± 107 Tg CO2e on a 100-y basis, mainly as a result of the reduced carbon (C) sink from the NOx-induced ozone effect on plant damage. On balance, the warming effects of gaseous Nr are partly offset by the cooling effects of N-induced carbon sequestration in terrestrial ecosystems. The large mitigation potentials through reductions in agricultural N2O and industrial NOx will accompany by a certain mitigation pressure from limited N-induced C sequestration in the future.