10. Mandy is studying the graph below, which plots carbon dioxide levels in the atmosphere
over time.
Parts per million
400
380
360
340
320
Atmospheric CO₂ Levels
(Mauna Loa Observatory)
-
Monthly values
Normalized values
p
1960 1970 1980 1990 2000 2010
Year
Graph and data copyright Scripps Institution of Oceanography,
NOAA Earth System Research Laboratory, December 2016
Mandy claims that human activity is not responsible for the trend in the data shown in the
graph. She argues that carbon dioxide is a natural part of Earth's atmosphere, and it is
constantly being released as a byproduct of cellular respiration.
Evaluate Mandy's claim and argument.