Exploring Regional-Scale Covariation: Atmospheric CO2 Anomalies Distribution Patterns, Vegetation Spread, and Climate Variables

The role of the terrestrial biosphere in regulating the global carbon cycle is critical, and it is crucial to comprehend the regional-scale source-sink dynamics and the underlying mechanisms for developing effective mitigation strategies. The present study investigated the dynamic relationship between atmospheric CO₂ levels and environmental factors in South Asia (SA), Southeast Asia (SEA) and West Asia (WA); these regions are home to diverse ecosystems, including tropical rainforests, mangroves, and coral reefs. Understanding carbon dynamics in these ecosystems is crucial as they play a significant role in sequestering and storing carbon. Utilizing data from 2015 to 2021 from the OCO-2 satellite, we analyzed the column-averaged dry air mole fraction of atmospheric CO₂ (XCO₂) along with variables such as precipitation, temperature, and Leaf Area Index (LAI), which distinguishes between high and low vegetation types. These environmental factors were synchronized with the spatial and temporal attributes of bias-corrected Lite (V11) level-2 daily files obtained from OCO-2. The majority of the zones in the area showed a positive relationship between their temperature anomalies and XCO₂ anomalies, albeit with varying lag periods (ranging from 0 to 4 months). This suggests that these zones could potentially act as sources of CO₂ during warmer periods. This trend was not observed in some regions, including the western plateau and hills, eastern coastal planes and hills, Pakistan, and Nepal, where the relationship between temperature and CO2 exhibited varying lag effects. The correlations were examined between the inter-annual variability (IAV) of detrended and depersonalized monthly-resampled anomalies of XCO₂ datasets and various environmental factors (anomalies) across diverse agroclimatic zones. In tropical savannah and humid subtropical climates, observed a positive correlation, between XCO₂ anomalies and precipitation whereas arid and semi-arid areas displayed negative correlations. These patterns indicate that increased rainfall in certain regions might enhance vegetation productivity, thereby reducing atmospheric CO₂ levels. Furthermore, in areas dominated by tropical aseasonal forests, a dense LAI correlated negatively with XCO₂, suggesting that more dense vegetation leads to increased CO₂ absorption through photosynthesis. In contrast, tropical seasonal forests showed a positive correlation between LAI and XCO₂, each with a unique lag period. Our analysis demonstrates the complex patterns of CO₂ anomalies distribution in SA, WA and SEA influenced by climatic factors (precipitation and temperature) and vegetation density (LAI). These insights are crucial for understanding regional CO₂ source-sink dynamics and formulating effective climate change mitigation strategies.