How would conditions on the surface of the earth be different without greenhouse gases?
Temperature ranges would be very great.
If we had no greenhouse gases then all the heat from the surface of the Earth would freely escape into space. This means that whenever there was no energy from the sun getting to the surface of the Earth, the temperature would drop freely. That means the temperature would drop much much more at night, and the temperatures at the poles would drop even more than they currently do.
It is difficult to imagine how much cooler it would get on the dark areas of the Earth since there is pretty much no example that we know of where there is a celestial body that has and atmosphere but no greenhouse gases.