An intensification of atmospheric CO 2 concentrations due to the surface temperature extremes in India

The terrestrial biosphere plays a pivotal role in removing carbon from the atmosphere. The removal processes are primarily affected by the presence of extreme temperature in the atmosphere. Little information is available on carbon removal response by the terrestrial biosphere during extreme temperature events over the Indian region. India has witnessed frequent and intense heatwaves in the recent past, and future projections about the frequency of heatwave occurrence suggest a further increase in the changing climate scenario. This study used surface CO 2 flux observations and satellite retrieved columnar and mid-tropospheric CO 2 concentrations to understand atmospheric CO 2 variability and its transport patterns with anomalously high-temperature events such as heatwave conditions over India. Intensification of temperature up to 32 °C has increased the atmosphere-biosphere CO 2 fluxes (carbon sink). But further intensification in temperature (> 32–33 °C), like those observed during heatwaves, tends to drive the ecosystem to act as a CO 2 source into the atmosphere due to reduced ability to absorb atmospheric CO 2 . Such excess CO 2 fluxes may lead to change in the atmospheric CO 2 concentration via atmospheric circulation or the vertical transport of the air masses from the near-surface to the upper levels in the atmosphere. The satellite observed CO 2 concentration is elevated by 2–3 ppm during the heatwave conditions over India. The impact of extreme temperature on the biospheric sink capability in the carbon cycle, leading to an increase in the atmospheric CO 2 concentration, is one of the significant outcomes of this study.