Carbon dioxide concentrations over the past 400,000 years Today
1
400
350
300
w
250
CO, concentration (ppm)
ruhan
200
150
100
50
0
400,000 BCE
300,000 BCE
200,000 BCE
100,000 BCE
Year
Complete the sentence.
Before the last century, the highest carbon dioxide concentration occurred roughly
325,000 years ago. The atmospheric concentration of carbon dioxide today is about
ppm higher than it was at that time.
50
100
150
200