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Title: Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude

Abstract

The atmospheric carbon dioxide (CO2) record displays a prominent seasonal cycle that arises mainly from changes in vegetation growth and the corresponding CO2 uptake during the boreal spring and summer growing seasons and CO2 release during the autumn and winter seasons. The CO2 seasonal amplitude has increased over the past five decades, suggesting an increase in Northern Hemisphere biospheric activity. It has been proposed that vegetation growth may have been stimulated by higher concentrations of CO2 as well as by warming in recent decades, but such mechanisms have been unable to explain the full range and magnitude of the observed increase in CO2 seasonal amplitude. Here we suggest that the intensification of agriculture (the Green Revolution, in which much greater crop yield per unit area was achieved by hybridization, irrigation and fertilization) during the past five decades is a driver of changes in the seasonal characteristics of the global carbon cycle. Our analysis of CO2 data and atmospheric inversions shows a robust 15 per cent long-term increase in CO2 seasonal amplitude from 1961 to 2010, punctuated by large decadal and interannual variations. Using a terrestrial carbon cycle model that takes into account high-yield cultivars, fertilizer use and irrigation, we findmore » that the long-term increase in CO2 seasonal amplitude arises from two major regions: the mid-latitude cropland between 256N and 606N and the high-latitude natural vegetation between 506N and 706 N. The long-term trend of seasonal amplitude increase is 0.311 ± 0.027 percent per year, of which sensitivity experiments attribute 45, 29 and 26 per cent to land-use change, climate variability and change, and increased productivity due to CO2 fertilization, respectively. Vegetation growth was earlier by one to two weeks, as measured by the mid-point of vegetation carbon uptake, and took up 0.5 petagrams more carbon in July, the height of the growing season, during 2001–2010 than in 1961–1970, suggesting that human land use and management contribute to seasonal changes in the CO2 exchange between the biosphere and the atmosphere.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1170108
Report Number(s):
PNNL-SA-107416
400409900
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Nature, 515(7527):393-397
Additional Journal Information:
Journal Name: Nature, 515(7527):393-397
Country of Publication:
United States
Language:
English

Citation Formats

Zeng, Ning, Zhao, Fang, Collatz, George, Kalnay, Eugenia, Salawitch, Ross J., West, Tristram O., and Guanter, Luis. Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude. United States: N. p., 2014. Web. doi:10.1038/nature13893.
Zeng, Ning, Zhao, Fang, Collatz, George, Kalnay, Eugenia, Salawitch, Ross J., West, Tristram O., & Guanter, Luis. Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude. United States. https://doi.org/10.1038/nature13893
Zeng, Ning, Zhao, Fang, Collatz, George, Kalnay, Eugenia, Salawitch, Ross J., West, Tristram O., and Guanter, Luis. 2014. "Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude". United States. https://doi.org/10.1038/nature13893.
@article{osti_1170108,
title = {Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude},
author = {Zeng, Ning and Zhao, Fang and Collatz, George and Kalnay, Eugenia and Salawitch, Ross J. and West, Tristram O. and Guanter, Luis},
abstractNote = {The atmospheric carbon dioxide (CO2) record displays a prominent seasonal cycle that arises mainly from changes in vegetation growth and the corresponding CO2 uptake during the boreal spring and summer growing seasons and CO2 release during the autumn and winter seasons. The CO2 seasonal amplitude has increased over the past five decades, suggesting an increase in Northern Hemisphere biospheric activity. It has been proposed that vegetation growth may have been stimulated by higher concentrations of CO2 as well as by warming in recent decades, but such mechanisms have been unable to explain the full range and magnitude of the observed increase in CO2 seasonal amplitude. Here we suggest that the intensification of agriculture (the Green Revolution, in which much greater crop yield per unit area was achieved by hybridization, irrigation and fertilization) during the past five decades is a driver of changes in the seasonal characteristics of the global carbon cycle. Our analysis of CO2 data and atmospheric inversions shows a robust 15 per cent long-term increase in CO2 seasonal amplitude from 1961 to 2010, punctuated by large decadal and interannual variations. Using a terrestrial carbon cycle model that takes into account high-yield cultivars, fertilizer use and irrigation, we find that the long-term increase in CO2 seasonal amplitude arises from two major regions: the mid-latitude cropland between 256N and 606N and the high-latitude natural vegetation between 506N and 706 N. The long-term trend of seasonal amplitude increase is 0.311 ± 0.027 percent per year, of which sensitivity experiments attribute 45, 29 and 26 per cent to land-use change, climate variability and change, and increased productivity due to CO2 fertilization, respectively. Vegetation growth was earlier by one to two weeks, as measured by the mid-point of vegetation carbon uptake, and took up 0.5 petagrams more carbon in July, the height of the growing season, during 2001–2010 than in 1961–1970, suggesting that human land use and management contribute to seasonal changes in the CO2 exchange between the biosphere and the atmosphere.},
doi = {10.1038/nature13893},
url = {https://www.osti.gov/biblio/1170108}, journal = {Nature, 515(7527):393-397},
number = ,
volume = ,
place = {United States},
year = {Thu Nov 20 00:00:00 EST 2014},
month = {Thu Nov 20 00:00:00 EST 2014}
}