A high concentration CO2 pool over the Indo-Pacific Warm Pool
R. Peter, J. Kuttippurath, Kunal Chakraborty, N. Sunanda
Abstract
Abstract Anthropogenic emissions have produced significant amount of carbon dioxide (CO 2 ) in the atmosphere since the beginning of the industrial revolution. High levels of atmospheric CO 2 increases global temperature as CO 2 absorbs outgoing longwave radiation and re-emits. Though a well-mixed greenhouse gas, CO 2 concentration is not uniform in the atmosphere across different altitudes and latitudes. Here, we uncover a region of high CO 2 concentration (i.e. CO 2 pool) in the middle troposphere (500–300 hPa) over the Indo-Pacific Warm Pool (IPWP, 40° E–140° W, 25° S–25° N), in which the CO 2 concentration is higher than that of other regions in the same latitude band (20° N–20° S), by using CO 2 satellite measurements for the period 2002–2017. This CO 2 pool extends from the western Pacific to the eastern Indian Ocean. Much of the CO 2 pool is over the western Pacific Ocean (74.87%), and the remaining lies over the eastern Indian Ocean (25.13%). The rising branch of Walker circulation acts as a “CO 2 Chimney” that constantly transports CO 2 released from the natural, human-induced and ocean outgassing processes to the middle and upper troposphere. The CO 2 pool evolves throughout the year with an average annual trend of about 2.17 ppm yr −1 , as estimated for the period 2003–2016. Our analysis further reveals that La Niña (El Niño) events strengthen (weaken) the CO 2 pool in the mid-troposphere. The radiative forcing for the CO 2 pool suggests more warming in the region and is a grave concern for global warming and climate change.