Recent decrease of the impact of tropical temperature on the carbon cycle linked to increased precipitation

• Published in: Nature Communications
• Main Authors: Zhang, Wenmin, Schurgers, Guy, Peñuelas, Josep, Fensholt, Rasmus, Yang, Hui, Tang, Jing, Tong, Xiaowei, Ciais, Philippe, Brandt, Martin
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: CCSD 2023
• Subjects: [SDU]Sciences of the Universe [physics]; South Pole; South pole
• Online Access: https://hal.science/hal-04042312; https://hal.science/hal-04042312v1/document; https://hal.science/hal-04042312v1/file/s41467-023-36727-2.pdf; https://doi.org/10.1038/s41467-023-36727-2

International audience Abstract The atmospheric CO 2 growth rate (CGR) variability is largely controlled by tropical temperature fluctuations. The sensitivity of CGR to tropical temperature $$\left({{{{\rm{\gamma }}}}}_{{{{\rm{CGR}}}}}^{{{{\rm{T}}}}}\right)$$ γ CGR T has strongly increased since 1960, but here we show that this trend has ceased. Here, we use the long-term CO 2 records from Mauna Loa and the South Pole to compute CGR, and show that $${{{{\rm{\gamma }}}}}_{{{{\rm{CGR}}}}}^{{{{\rm{T}}}}}$$ γ CGR T increased by 200% from 1960–1979 to 1979–2000 but then decreased by 117% from 1980–2001 to 2001–2020, almost returning back to the level of the 1960s. Variations in $${{{{\rm{\gamma }}}}}_{{{{\rm{CGR}}}}}^{{{{\rm{T}}}}}$$ γ CGR T are significantly correlated with changes in precipitation at a bi-decadal scale. These findings are further corroborated by results from a dynamic vegetation model, collectively suggesting that increases in precipitation control the decreased $${{{{\rm{\gamma }}}}}_{{{{\rm{CGR}}}}}^{{{{\rm{T}}}}}$$ γ CGR T during recent decades. Our results indicate that wetter conditions have led to a decoupling of the impact of the tropical temperature variation on the carbon cycle.