To begin with, carbon dioxide molecules that leave the surface of the water are no longer replaced by molecules returning to the liquid.
(carbon dioxide molecules; leave; the surface of the water) (carbon dioxide molecules that leave the surface of the water; are replaced; by molecules; T:no longer) (molecules; returning; to the liquid)
carbon dioxide molecules carbon dioxide molecules that leave the surface of the water molecules
leave are replaced returning
the surface of the water
by molecules T:no longer
to the liquid