56 million rotting dead injuns had to put back some CO2 and methane. Also, lightning caused fires would have burned until the rainy season because no one could put them out.
No mention of volcanic activity which would put more gas in the air than all of man’s activity.
And then there is that decomposing Norwegian Blue Parrot... (/sarc)
Maybe then.
However, presently, whatever the effects may be or not be, it IS true that human activity, overall, does exceed volcanos in the amount of CO2 released to the atmosphere. This can be proven by looking up what the volcanologists say volcanos are releasing, globally, and then look up typical human sources (say, an average car driven, say, 5,000 miles a year) and the calculation of how much CO2 is created by the burning of a gallon of gasoline or (10%) gasohol. Apply some high school math and estimates of the # of autos in the world. Do the same procedure for other sources.
Alternately, if you want to skip the research and math, the EIA estimated energy related US CO2 production @ 5,140 million metric tons in 2017. (This does not include biofuels (considered carbon neutral), biological and agricultural releases, etc. Ie., things like you and me breathing.) That's just for the US - worldwide, the figure for energy related CO2 production is estimated at 24 billion tons a year. Volcanos come in at, according to the USGS, 0.2 billion tons per year. Other sources (mid ocean ridges, etc.) run that number up to 600-700 million tons of CO2 per year (it depends a bit on which reference you read), but, clearly, humans' huge population puts us well in the lead.
By far the most abundant gas released by volcanoes is water vapor. However, there is little evidence that even in "busy" volcanic years, this water vapor has a significant global warming effect -- probably because the particulates are a bigger factor in the direction of cooling.
I state this because we FREEPERS and Conservatives need to be as accurate as possible with our facts. Stating "facts" that are easily disproven tends to blow up anything else we say...