One can calculate the radiative equilibrium temperature of a planet given its distance from tbe sun by radiative balance. Heat in = heat out. Heat out varies as T^4..
For Earth, Venus snd Mars the surface temperature is higher.
This is because atmospheric gases absorb radiated infra-red from the surface. Heat from the sun is deposited at the surface but can't be lost to space from there. So heat is transported up through the atmosphere until the overlying layers of absorbing gases are insufficient to stop it radiating away. This heat current requires a thermal gradient. So the surface is hotter than predicted by radiative balance.
It is the assymetric molecules that absorb this radiation. Notably CO2, NOx, SO2, and H2O. Not O2 or N2
The wster cycle is rapid so it responds to the balance driven by the other gases. It ampifies their effect since higher T leads to higher water content.
The baseline concentration of these gases explains the surface tempersture of the earth.
The concentration of these forcing gases has increased significantly since industrialisation. Heat has to get higher in the atmosphere to be radiated away. The current is the same, so the gradient is the same. Same gradient... longer distance... bigger T difference between radiative equilibrium and surface T... higher surface T.
isotopic evidence demonstrates the source of the extra CO2 is burning of fossil fuels.
So basic, well understood science predicts that the climate should have warmed.
Predicting the detailed effects is very complex.
But believing there is no significant effect is scientifically illiterate.... it's like denying the absorption spectrum of CO2.