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
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: South Pole; South pole
• Online Access: https://curis.ku.dk/portal/da/publications/recent-decrease-of-the-impact-of-tropical-temperature-on-the-carbon-cycle-linked-to-increased-precipitation(b07570ba-7b92-4fdd-a6c8-519b77feaa49).html; https://doi.org/10.1038/s41467-023-36727-2; https://curis.ku.dk/ws/files/339269687/s41467_023_36727_2_1_.pdf

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.