All of the Following Statements About Atmospheric Carbon Dioxide Levels

question 25

Multiple Choice

All of the following statements about atmospheric carbon dioxide levels are true,EXCEPT

• A) levels are currently measured directly from the air.
• B) historic levels are measured by examining air bubbles trapped in ice cores.
• C) historic levels of CO₂ reached present-day levels only twice before.
• D) CO₂ levels cycle in patterns that correlate with major ice ages.
• E) since the late 1800s,atmospheric CO₂ has increased 35%.