A succinct writeup of an odd observation; that northern and southern hemisphere CO2 concentrations are remaining very close as they grow.
As most human-originated CO2 release occurs in the northern hemisphere, and as CO2 has previously been observed to take upwards of a half a year to propagate between hemispheres, the implication is that the atmospheric increases are global (or perhaps equatorial) and therefore not, primarily, human-originated.
N.B. human-originated != human-caused. The oceans are our largest carbon sink and may tend to release CO2 as temperatures rise; this tells us nothing of the underlying cause. It is, nonetheless, a fascinating data point.
The source of the data about how long CO2 takes to propagate is also fascinating. Apparently 1950s/60s nuclear tests provided an observable carbon-14 variation which could be measured and its propagation time calculated. I’m reminded of the stunning data about the impact of air traffic on planetary albedo and daily temperature variations that was provided by the shutdown of aviation in the USA on September 11-13, 2001. Finding good in the bad.