Yes, Mauna Loa is a volcano, and yes, volcanos do outgas – including CO2. But scientists are not stupid. They know this. The records for Mauna Loa show a clear annual cycle superimposed on an overall rise with time. There are no random spikes of the type that would indicate contamination from outgassing. And, okay, let's throw out Mauna Loa. A station in the Antarctic far from volcanos, SUVs and coal-fired power plants shows the same pattern (albeit with a slight lag because most of the anthropogenic sources are in the northern hemisphere). In fact, there are dozens of stations around the globe that all show the same trend. Mauna Loa gets the attention because its record is the longest. But, where the other stations overlap in time, they show the same trend.