NOAA Earth System Research Laboratory makes surface measurements of all of the important greenhouse gases at stations across the globe. They have a fantastic website where you can plot the measurements from any stations. You can see there the general increase in greenhouse gases over the years as well how the trend is varies across the globe. For example, carbon dioxide is lower in the southern hemisphere than in the northern hemisphere, consistent with the main source being located in the northern hemisphere. You can also see how the seasonal cycle is much smaller at high southern latitudes, which is consistent with the plants driving the seasonal cycle being mainly located in the northern hemisphere. You can use this link for question 10 of Chap. 5.
Here is a simple climate/carbon-cycle model that you can play around with. It was designed through a NASA Education grant by the Challenger Center for Space Science Education. It does a good job of teaching about balance, flows, reservoirs, natural processes and human influences. [this link appears to be dead; Dec. 28, 2018]
A thorough analysis of the carbon budget of the atmosphere can be found in here: Le Quéré, C. et al.: Global carbon budget 2013, Earth Syst. Sci. Data, 6, 235-263, doi:10.5194/essd-6-235-2014, 2014.
You can read more about Ralph Keeling's oxygen measurements here: Keeling, R. F. and Maning, A. C.: Studies of Recent Changes in Atmospheric O2 Content, in: Treatise on Geochemistry, Vol. 4, edited by: Keeling, R. F. and Russell, L., Amsterdam, Elsevier, 385–404, 2013.
This paper talks about the PETM and where the greenhouse gases that caused it came from.