A graph of atmospheric carbon dioxide concentration over time is shown below.
CO, Concentration (ppm)
Change in Atmospheric CO2
Concentration over Time
380
360
340 -
320
300-
280 -
200-
240-
220 -
200+
Scientists are investigating the cause of the large increase in
atmospheric carbon dioxide concentration since about 1800.
Which of the following provides the best explanation for the
increase?
A. eruptions of large volcanoes
B. use of fossil fuels by humans
C. natural fluctuations of climate
D. photosynthesis by photoplankton
1000 1200 1400 1600 1500 2000
Year