X1011788035-00269-64647</DOCNO> NDP Background Information A dramatic increase in the atmospheric concentration of carbon dioxide (CO 2 ) has been directly observed over the past 30 years (Keeling et al.
(A dramatic increase in the atmospheric concentration of carbon dioxide; has been directly observed; T:over the past 30 years)
A dramatic increase in the atmospheric concentration of carbon dioxide
has been directly observed
T:over the past 30 years