These wackos seem to forget that averages are made up of extremes. The early 1900's have many cases of extreme weather events both hot and cold. And they have yet to explain the output of volcanoes and sunspot activity. Or how about the massive amounts of CO2 that the oceans put out?
And as has been stated many times, CO2= plant food.
According to National Geographic, CO2 has varied between .033 percent and .036 percent of the atmosphere.
It was projected to be many times higher than that by now but it didn't happen. They are trying now to figure out where all the projected CO2 went.