Keeling's Reports from Mauna Loa Demonstrated ______________

Keeling's reports from Mauna Loa demonstrated ______________

A) the presence of El Niño
B) that sediments deposited on the seafloor can yield clues about past climates
C) that as distances from cities decreased,CO2 concentrations increased
D) an increase in tropospheric CO2 from the 1950s to present
E) that CO2 levels have been stable over the last 40 years