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

Wenmin Zhang; Guy Schurgers; Josep Peñuelas; Rasmus Fensholt; Hui Yang; Jing Tang; Xiaowei Tong; Philippe Ciais; Martin Brandt

doi:10.1038/s41467-023-36727-2

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

Nat Commun. 2023 Feb 21;14(1):965. doi: 10.1038/s41467-023-36727-2.

Authors

Wenmin Zhang¹, Guy Schurgers², Josep Peñuelas^{3

4}, Rasmus Fensholt², Hui Yang⁵, Jing Tang^{6

7}, Xiaowei Tong⁸, Philippe Ciais⁹, Martin Brandt²

Affiliations

¹ Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark. wenminzhg@gmail.com.
² Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.
³ CSIC, Global Ecology Unit CREAF-CEAB-UAB, Cerdanyola del Vallès, 08193, Catalonia, Spain.
⁴ CREAF, Cerdanyola del Vallès, 08193, Catalonia, Spain.
⁵ Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, 07745, Jena, Germany.
⁶ Department of Physical Geography and Ecosyste m Science, Lund University, Lund, Sweden.
⁷ Department of Biology, University of Copenhagen, Copenhagen, Denmark.
⁸ Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China.
⁹ Laboratoire des Sciences du Climat et de l'Environnement, CEA CNRS UVSQ, Gif-sur-Yvette, France.

Abstract

The atmospheric CO₂ growth rate (CGR) variability is largely controlled by tropical temperature fluctuations. The sensitivity of CGR to tropical temperature [Formula: see text] has strongly increased since 1960, but here we show that this trend has ceased. Here, we use the long-term CO₂ records from Mauna Loa and the South Pole to compute CGR, and show that [Formula: see text] 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 [Formula: see text] 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 [Formula: see text] 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.