I can come up with a couple alternatives to your explanation:
1. Our current carbon levels haven’t been high long enough for their total effects in temperature to be felt yet, given the size of the system they must affect. 50 years is a blip on geological timescales.
2. There are cascading effects to high CO2 levels that will take longer to manifest themselves and which will raises the temperatures further. Permafrost melting and releasing methane is a possible example.
The orbit of the earth around the sun, and the activity of the sun itself are also possible culprits. I'm sure actual climatologists have a better explanation.
1. Our current carbon levels haven’t been high long enough for their total effects in temperature to be felt yet, given the size of the system they must affect. 50 years is a blip on geological timescales.
2. There are cascading effects to high CO2 levels that will take longer to manifest themselves and which will raises the temperatures further. Permafrost melting and releasing methane is a possible example.