How would they know? They spend all their time studying meteors.
LOL, studying meteors
If you look at the dissolved CO2 from ice core samples from the poles for the past 10,000 yrs it is pretty clear.
It shows that the temp each season was pretty stable over the years. In the last 100 yrs as the CO2 levels raise so did the temp ( a lot).
We know what the temp was each past century due to the dissloved 0xygen atoms and % of each kind of isotope.
( * atmosphere temp = % of various Oxygen isotopes in the atmosphere)
Plot the temp vs CO2 data and you get a near perfect linear regression line fit.
When the conclsuion is this clear, i don't even know why ths up for debate any longer.
I don't debate glbal warning with many as it is settled science based on the data .
If they try and tell me glbal warning is a hoax, I quote the data conclusions above.
They often scoff at my data but come back wth some silly reply that makes no sense.
Often they argue by making a point has nothing to do to refute the data I try to explain.
Most have no idea what the signifigance of the dissolved O2 isotopes mean . Many seem clueless when I mention
the analysis is done via gas chromatograph or Mass spec, etc.
Ths is like trying to debate baseball with someone who doesn't know how many strikes a batter gets