Weak northern and strong tropical land carbon uptake from vertical profiles of atmospheric CO2

Science. 2007 Jun 22;316(5832):1732-5. doi: 10.1126/science.1137004.


Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed annual-mean vertical CO2 gradients estimate weaker northern uptake of -1.5 petagrams of carbon per year (Pg C year(-1)) and weaker tropical emission of +0.1 Pg C year(-1) compared with previous consensus estimates of -2.4 and +1.8 Pg C year(-1), respectively. This suggests that northern terrestrial uptake of industrial CO2 emissions plays a smaller role than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for CO2.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.