Cleaning up nitrogen pollution may reduce future carbon sinks

Baojing Gu*, Xiaotang Ju, Yiyun Wu, Jan Willem Erisman, Albert Bleeker, Stefan Reis, Mark A. Sutton, Shu Kee Lam, Pete Smith, Oene Oenema, Rognvald I. Smith, Xuehe Lu, Xinyue Ye, Deli Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Biosphere carbon sinks are crucial for reducing atmospheric carbon dioxide (CO2) concentration to mitigate global warming, but are substantially affected by the input of reactive nitrogen (Nr). Although the effects of anthropogenic CO2 emission and nitrogen deposition (indicated by Nr emission to atmosphere) on carbon sink have been studied, it is unclear how their ratio (C/N) changes with economic development and how such change alters biosphere carbon sinks. Here, by compiling datasets for 132 countries we find that the C/N ratio continued to increase despite anthropogenic CO2 and Nr emissions to atmosphere both showing an asymmetric para-curve with economic growth. The inflection points of CO2 and Nr emissions are found at around $15,000 gross domestic product per capita worldwide. Economic growth promotes the use of Nr and energy, while at the same time increases their use efficiencies, together resulting in occurrences of inflection points of CO2 and Nr emissions. Nr emissions increase slower but decrease faster than that of CO2 emissions before and after the inflection point, respectively. It implies that there will be relatively more anthropogenic CO2 emission but less N deposition with economic growth. This may limit biosphere carbon sink because of relative shortage of Nr. This finding should be integrated/included in global climate change modelling. Efforts, such as matching N deposition with carbon sequestration on regional scale, to manage CO2 and Nr emissions comprehensively to maintain a balance are critical.

Original languageEnglish
Pages (from-to)56-66
Number of pages11
JournalGlobal Environmental Change
Early online date22 Dec 2017
Publication statusPublished - 30 Jan 2018

Bibliographical note

This study was supported by the Melbourne Early Career Researcher Grant Scheme and Australian Research Council ( DE170100423 ), National Key Research and Development Project of China ( 2016YFC0207906 ), Natural Science Fund for Distinguished Young Scholars of Zhejiang Province (No. LR15G030001 ), National Natural Science Foundation of China (No. 41773068 , 41425007 ) and the “973” Program ( 2014CB953803 ) of the Chinese Ministry of Science and Technology . The work contributes to the UK-China Virtual Joint Centre on Nitrogen “N-Circle” funded by the Newton Fund via UK BBSRC/NERC ( BB/N013484/1 ), and Australia-China Joint Research Centre – Healthy soils for sustainable food production and environmental quality. We would like to thank Y. Min for the support on inflection point analysis. Appendix A


  • Carbon sink
  • Climate change
  • CO emission
  • Economic development
  • Nitrogen deposition
  • Stoichiometry


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