Spatio temporal Patterns of Atmospheric CO2 Emissions and its Linkages to the Land use Land cover changes and Climate over the Indian subcontinent

Abstract

The Intergovernmental Panel for Climate Change (IPCC) reported that carbon dioxide (CO2) from anthropogenic emissions is the major contributor to radiative forcing in the atmosphere (IPCC, AR6). The recorded monthly average atmospheric CO2 level in the Mauna Loa Observatory (elevation of about 3397 m) was 421 ppm during March 2023, the highest level since the accurate measurements began 65 years ago. The accelerating CO2 mixing ratios were attributed to changes in land use and land cover (LU/LC). After industrialization (around 1760), CO2 emissions from fossil fuel burning started and became the most significant contributor to the global carbon budget (Ballantyne et al., 2012). Since the pre-industrial period, the burning fossil fuel and LU/LC changes have increased by 40 and 150 % for CO2 and CH4 mixing ratios, respectively (Huang et al., 2016). Recent studies suggest that the CO2 emissions from cement production exceeded global fossil fuel emissions in the past two decades (Andrew, 2018). CO2 mixing ratio levels in the atmosphere are controlled by the combined effect of sources and sinks. Only about half the amount of CO2 released remains in the atmosphere, whereas two major sinks, the terrestrial biosphere, and oceans, absorb the remaining part (Andres et al., 1996). Hence, monitoring and maintaining long-term records of atmospheric CO2 measurements are essential to understanding the carbon cycle and predicting the future behaviour of the controlling factors: photosynthesis, respiration, biomass, fossil fuel burning, and air-sea exchange processes (Machida et al., 2002). newlineThe present thesis work is aimed at understanding and assessing the CO2 variability over the Indian region using three approaches: ground-based, satellite data, and model simulations, and further integrating them to provide a comprehensive estimate of CO2 concentrations and their variability. The impact of LU/LC and its changes on CO2 emissions are quantified using ground-based observations and model simulations from 2013 to 2022. In additio