The Greenhouse theory was always just hot air.
The Sun is the source of all heat on earth.
When it varies we get warmer or colder.
RE: Sun. Absolutely!
Nobody can tell you what the ideal temperature of the Earth should be. We only have had satellites measuring the atmosphere since the 70s. Between then and now is a sneeze for the Earth. You can not make long term observations of a chaotic, multivariable complex system on such a short term and predict the future. At all. All of the land based weather measurements only go back as far as the late 1700s. And how accurate are they? The error bars are probably more than what the models say we should warm in the next 100 years. Most of the weather stations are in the Northern Hemisphere, in the USA and Europe. What about 70% of the Earth that is covered by water with no weather stations. What about most of the Southern Hemisphere or Asia?
The simple fact that temperature and CO2 do not track should blow AGW theory out of the water.