Open AccessInferring CO2 fertilization effect based on global monitoring land-atmosphere exchange with a theoretical model
Author(s) -
Masahito Ueyama,
Kazuhito Ichii,
Hideki Kobayashi,
Tomo’omi Kumagai,
Jason Beringer,
Lutz Merbold,
Eugénie Euskirchen,
Takashi Hirano,
Luca Belelli Marchesini,
Dennis Baldocchi,
Taku M. Saitoh,
Yasuko Mizoguchi,
Keisuke Ono,
Joon Kim,
Andrej Varlagin,
Minseok Kang,
Takanori Shimizu,
Yukio Kosugi,
M. Syndonia BretHarte,
Takashi Machimura,
Yukiko Matsuura,
Takeshi Ohta,
Kentaro Takagi,
Satoru Takanashi,
Yukio Yasuda
Publication year - 2020
Publication title -
environmental research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.37
H-Index - 124
ISSN - 1748-9326
DOI - 10.1088/1748-9326/ab79e5
Subject(s) - transpiration , environmental science , evapotranspiration , primary production , eddy covariance , atmospheric sciences , photosynthesis , carbon cycle , photosynthetically active radiation , atmosphere (unit) , water vapor , climatology , ecosystem , meteorology , ecology , botany , biology , geology , physics
Rising atmospheric CO 2 concentration ([CO 2 ]) enhances photosynthesis and reduces transpiration at the leaf, ecosystem, and global scale via the CO 2 fertilization effect. The CO 2 fertilization effect is among the most important processes for predicting the terrestrial carbon budget and future climate, yet it has been elusive to quantify. For evaluating the CO 2 fertilization effect on land photosynthesis and transpiration, we developed a technique that isolated this effect from other confounding effects, such as changes in climate, using a noisy time series of observed land-atmosphere CO 2 and water vapor exchange. Here, we evaluate the magnitude of this effect from 2000 to 2014 globally based on constraint optimization of gross primary productivity (GPP) and evapotranspiration in a canopy photosynthesis model over 104 global eddy-covariance stations. We found a consistent increase of GPP (0.138 ± 0.007% ppm −1 ; percentile per rising ppm of [CO 2 ]) and a concomitant decrease in transpiration (−0.073% ± 0.006% ppm −1 ) due to rising [CO 2 ]. Enhanced GPP from CO 2 fertilization after the baseline year 2000 is, on average, 1.2% of global GPP, 12.4 g C m −2 yr −1 or 1.8 Pg C yr −1 at the years from 2001 to 2014. Our result demonstrates that the current increase in [CO 2 ] could potentially explain the recent land CO 2 sink at the global scale.