Impact of Global Climatic Phenomena on the Carbon Exchange Dynamics of the Indian Terrestrial Biosphere

A better understanding of the country-scale terrestrial biospheric carbon dioxide (CO₂) budget is crucial for formulating national climate policies aimed at limiting carbon emissions. The scarcity of continuous and dense regional CO₂ measurements in India poses a significant challenge to accurately quantifying its carbon budget. Moreover, there are no observation-based studies investigating the regional carbon-climate interactions and carbon cycle response due to large-scale climatic events currently exist. In this study, we use the OCO-2 satellite atmospheric CO₂ column (XCO₂) retrievals, Solar Induced Fluorescence (SIF) and various observational data to study the Indian terrestrial biosphere’s response to large-scale climatic events such as El Niño-Southern Oscillation and Indian Ocean Dipole (IOD). The XCO₂ data was assimilated in an ensemble of eight global top-down CO₂ flux inverse models as part of the OCO-2 v10-Ext multi-model intercomparison project. We found a decrease in Indian terrestrial biosphere carbon uptake during El Niño and an increase during La Niña and positive IOD events. The increase in carbon uptake, driven by pIOD and La Niña events (~150 TgC) accounts for approximately one-quarter of India's annual fossil fuel carbon emissions. Studies indicate that the frequency of pIOD and La Niña events may rise under future global warming scenarios. This can potentially enhance the capacity of the Indian terrestrial biosphere to sequester more atmospheric carbon. Satellite-derived carbon-climate constraints over India as found in this study provide critical insights for developing effective strategies to achieve net-zero emissions in the future.

Acknowledgements: OCO-2 v10-Ext MIP modelers.