Most of the CO2 we burned into the air in 1950 will still be there in 2100 along with some from 1900.
This is an artists conception of the surface of Venus. It is probably not very accurate. For one thing, its atmosphere is undoubtedly much denser and the place much more hellish. The point is, this is the path we have set the earth on. If we continue for a couple of more decades with the level of carbon inputs we have been injecting into the atmosphere, we will almost certainly convert the earth into something horrible and lifeless like this. Carbon in the atmosphere is a cumulative thing and it just keeps heating up the atmosphere until it spirals out of control. It won't make much difference if in 2100 we have converted to carbon free energy; the damage will already have been done.