The link between climate and CO2 exists (or doesn't) regardless of whether the experience is man made or not (for example if a huge volcano had piped out the same CO2 as man, and the climate did or didn't warm, that would be a test).
That seems a rather flawed example because volcanoes do
not emit
only CO2. Volcanic ash or dust released into the atmosphere during an eruption will shade sunlight and cause a temporary cooling in the region. The sulphur dioxide emitted by volcanoes produces an even more significant cooling, and its effect lasts longer and is more wide-spread. The sulphur dioxide moves into the upper atmosphere where it combines with water to produce sulphuric acid which forms into a haze of tiny droplets reflecting incoming solar radiation.
If the volcanic activity is massive enough, this cooling effect could continue for a several years causing an expansion of the ice cover at the poles which results in a greater 'albedo' area, which reflects yet more incoming solar radiation, and prolongs the cool period.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL050168"Here we present precisely dated records of ice‐cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium."https://earthobservatory.nasa.gov/images/89813/satellite-catalogs-volcanic-sulfur-emissions“Many people may not realize that volcanoes are continuously releasing quite large amounts of gas, and may do so for decades or even centuries,” said Michigan Technological University volcanologist Simon Carn, the lead author of the study. “Because the daily emissions are smaller than a big eruption, the effect of a single plume may not seem noticeable. But the cumulative effect of all volcanoes can be significant. In fact, on average, volcanoes release most of their gas when they are not erupting.”Apparently natural volcanic and man-made CO2 emissions have the same carbon isotopic fingerprint. This makes it impossible to determine how much of the current, elevated CO2 levels are due to the burning of fossil fuels, and how much are due to volcanic activity.
Alarmist will of course claim that the amount of CO2 in the atmosphere due to volcanoes is relatively small, despite the obvious fact that it is not known how many volcanoes on land and sea are continuously emitting CO2, whether the volcanoes are erupting or not. How scientific of them!
One has to admit these alarmists have a firm grasp on the methodology of science.
Here's an article linking recent research on volcanic CO2 emissions. However, if you are an alarmist, you must
not read this scientific research because
it must be junk science. Any research that casts doubt on the validity of the 97% consensus, cannot be true because 'the science is settled'. You've been warned!
http://www.plateclimatology.com/discovery-of-massive-volcanic-co2-emissions-puts-damper-on-global-warming-theory