How has the increase in global CO2 been attributed to an anthropogenic cause?
It would seem to me that this could be definitively determined on the basis of placing gas spectrometers on the exhausts of a stratified random sample of exhaust pipes: (a) Motor vehicles, (b) Aircraft (c) smoke stacks of factories. et cetera. Has this been done or are we just guessing?
There is a very great answer show below that essentially says from:
(a) The known GHG emissions of the fossil fuels
(b) The known fossil fuel consumption for last year
(c) The known increase in atmospheric GHG last year
we can use simple arithmetic to determine how much of this emission has an anthropogenic cause.
Because the ocean is such a powerful GHG sink, I would expect that the above process might account for more than 100% of the increase of atmospheric GHG.
I am still trying to find the data to quantify the above
The EPA relied on the IPCC assessment:
Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years.1 https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions
- IPCC (2007). Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis.