How much does the atmosphere weigh over each square kilometer (km2)? Recall that 106 m2 = 1 km2 .
Thus according to these calculations, we are adding CO2 to the atmosphere at the rate of approximately Answer: __________ percent per year. At this rate, can we account for the observed increase in CO2 in the atmosphere since 1950s? CO2 content in 1959 was measured at 316 ppm (parts per million) and was 380 ppm in 2005. What is the percentage increase in CO2 over this forty-six-year interval.