Answer:
Almost immeasurably small.
Explanation:
The STORY is that humans are BAD for the environment and have caused a HUGE change in the amount of CO₂ in the atmosphere.
Let's look at the reports and draw our own conclusions.
Current CO₂ levels are 409.8 parts per million (PPM)
at the beginning of the Industrial revolution in the 1700's, the presumed beginning of the huge increase in CO₂ the level was about 280 PPM
For perspective lets assume we capture the whole atmosphere and squish it down to 2400 one liter bottles of air
That's 100 cases of 24 bottles per case.
We now separate all the air components into their own bottles
Nitrogen is 78% of our air, so we subtract 78 cases from our 100 leaving 22
Subtracting Oxygen at 21% of air leaves 1 case of liter bottles left
Of those 24 bottles, Argon makes up 0.93% of air so we subtract 22 bottles
The remaining two bottles contain all of the other gasses in our air, One of those bottles contains CO₂.
If we take the CO₂ levels from the 1700's at about 280 PPM as a baseline and assume ALL of the increase is human caused, that is (410 -280) / 280 = 46 % of the total.
The human caused addition of CO₂ would be 460 mililiters out of 2400 liters over the course of 250 years
The claim is, that less than half of a liter of CO₂ out of 2400 liters of air is responsible for heating not only the gas in all the other bottles but also the surface of the earth itself.
Personally, it boggles my mind.
And it says NOTHING of a far more powerful greenhouse gas that is far more prevalent in the atmosphere...water vapor.
Water vapor is about 1% of air at sea level and about 0.4% overall. It was not considered in the above analysis because water vapor can condense out and is not a constant in the air.
Notice that there is about 100 times the amount of water vapor in the air as compared to CO₂. Water vapor also has between 4 and 8 times the greenhouse effect that CO₂ does.
Makes one wonder why we choose to pick on CO₂.
