Based on the Keeling Curve graph, what causes the annual rise and fall of carbon
dioxide levels in the atmosphere? In other words, why does the graph have a
zigzag pattern?
420
Mauna Loa Observatory, Hawaii
Monthly Average Carbon Dioxide Concentration
Data from Scripps CO, Program Last updated February 2020
COâ‚‚ Concentration (ppm)
410
400
390
380
370
360
www
350
340
330
320
310
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020
Year
O Oil refineries are shut down periodically in the summer
People use more energy in the winter
