Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors

Atui Jain, Xiaojuan Yang, Haroon Kheshgi, A. David McGuire, Wilfred Post, David Kicklighter

Research output: Contribution to journalArticle

Abstract

Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen availability influences terrestrial carbon sinks and sources in response to changes over the 20th century in global environmental factors including atmospheric CO2 concentration, nitrogen inputs, temperature, precipitation and land use. The two versions of ISAM vary in their treatment of nitrogen availability: ISAM-NC has a terrestrial carbon cycle model coupled to a fully dynamic nitrogen cycle while ISAM-C has an identical carbon cycle model but nitrogen availability is always in sufficient supply. Overall, the two versions of the model estimate approximately the same amount of global mean carbon uptake over the 20th century. However, comparisons of results of ISAM-NC relative to ISAM-C reveal that nitrogen dynamics: (1) reduced the 1990s carbon sink associated with increasing atmospheric CO2 by 0.53 PgC yr -1 (1 Pg = 1015g), (2) reduced the 1990s carbon source associated with changes in temperature and precipitation of 0.34 PgC yr -1 in the 1990s, (3) an enhanced sink associated with nitrogen inputs by 0.26 PgC yr-1, and (4) enhanced the 1990s carbon source associated with changes in land use by 0.08 PgC yr in the 1990s. These effects of nitrogen limitation influenced the spatial distribution of the estimated exchange of CO2 with greater sink activity in high latitudes associated with climate effects and a smaller sink of CO2 in the southeastern United States caused by N limitation associated with both CO 2 fertilization and forest regrowth. These results indicate that the dynamics of nitrogen availability are important to consider in assessing the spatial distribution and temporal dynamics of terrestrial carbon sources and sinks.

Original languageEnglish (US)
Article numberGB4028
JournalGlobal Biogeochemical Cycles
Volume23
Issue number4
DOIs
StatePublished - Oct 1 2009

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

Fingerprint Dive into the research topics of 'Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors'. Together they form a unique fingerprint.

  • Cite this