Predict the likely effect to the average global surface temperature when greenhouse gas levels increase in ...

Question

...the atmosphere

Answer 1

It is now known that CO2 levels are causing the atmospheric temperatures at low levels to increase and at high levels to decrease.

:-D Better watch out or we could be living in the tropics.

Answer 2

Not much change because it would have to be uniform and for an extended period of time.  Weather adjusts to change and that is why temperatures rise slowly worldwide.