Dry air is 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide so varying amounts of water vapor- depending on humidity. Some gases however strongly absorb infrared radiation and trap it in the atmosphere and can therefore result in elevated global temperatures. Therefore they are termed greenhouse gases. Which greenhouse gas have we observed a marked increase in atmospheric concentrations in the last 100 years? A. methane (CH4)
B. carbon monoxide
C. carbon dioxide
D. ozone (03)
E. oxygen
F. nitrogen
G. water vapor (H20)