Human activities in the recent past have caused the increased concentration of carbon dioxide in the atmosphere, but a lot of it does not remain in the lower atmosphere because of 1. Its escape into the outer stratosphere. 2. the photosynthesis by phytoplankton in the oceans. 3. the trapping of air in the polar ice caps. Which of the statements given above is/ are correct ?

Human-induced carbon dioxide (CO2) emissions do not entirely remain in the lower atmosphere due to various natural sinks. Phytoplankton in the oceans play a critical role by consuming CO2 during photosynthesis, incorporating carbon into their biomass, and facilitating its transfer to the deep ocean [2]. While the oceans absorb approximately one-third of anthropogenic CO2, this process leads to ocean acidification. Statement 1 is incorrect because CO2 is a heavy gas that remains primarily in the troposphere; it does not 'escape' into the outer stratosphere in significant quantities to reduce atmospheric concentration. Statement 3 is incorrect because while polar ice caps contain trapped air bubbles that provide historical climate records, they do not act as a contemporary sink for removing large volumes of current anthropogenic CO2 emissions from the lower atmosphere. Thus, only the biological pump driven by phytoplankton is a valid mechanism among the choices provided [4].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 14: Marine Organisms > The Carbon Cycle and climate change > p. 208
2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Carbon and Oxygen Cycles > p. 19
3. [4] https://pubmed.ncbi.nlm.nih.gov/19093090/