B066-0013
Increasing atmospheric CO2 seasonal amplitude caused by amplified cropland productivity
Friday, 11 December 2020
Poster
Liyin He1, Yi Yin2, Brendan K Byrne3, Christian Frankenberg4, Jung Martin5, Philipp Koehler6, Dien Wu7 and Sophia Walther5, (1)California Institute of Technology, Environmental Science and Engineering, Pasadena, CA, United States, (2)California Institute of Technology, Division of Geological and Planetary Sciences, Pasadena, CA, United States, (3)Jet Propulsion Laboratory, Pasadena, CA, United States, (4)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (5)Max Planck Institute for Biogeochemistry, Jena, Germany, (6)California Institute of Technology, Pasadena, CA, United States, (7)California Institute of Technology, Pasadena, United States
Abstract:
The seasonality of atmospheric carbon dioxide (CO
2) concentrations arises mainly from photosynthetic changes of terrestrial ecosystem, with CO
2 uptake during growing seasons and CO
2 release during non-growing seasons. The ground and aircraft-based CO
2 measurements both show that the atmospheric CO
2 seasonal amplitude has been increasing over the recent decades. Many studies have reported that the increasing atmospheric CO
2 seasonal amplitude is attributed to the enhanced plant activity in high northern latitudes (above 40°), either due to warming effect or CO
2 fertilization. However, there is still
heated debate to fully explain the magnitude of observed CO
2 seasonal amplitude increases.
Here we suggest that the increasing cropland productivity during the past two decades contributes to the increasing atmospheric CO2 seasonal amplitude. Both ground and satellite measurements show that crops have much higher photosynthetic activity in peak growing seasons than other biome types. In global agricultural hotspots (the United States, China, India and Europe), the annual peak cropland productivity has increased ~10% in the past two decades. We use novel data driven and remote sensing approaches to constrain the carbon fluxes in these cropland dominated regions. We then compare the simulated CO2 amplitude with the observation and quantify the contribution of cropland carbon fluxes to the observed seasonal amplitude of CO2. Our study suggests that enhanced cropland productivity have significantly contributed to the carbon interactions between the biosphere and the atmosphere.
