It is one thing to establish an association of increased concentrations of \(\mathrm{CO}_{2}\) and other GHGs in the atmosphere and future global warming, but it is an entirely different matter to be able to predict with a reasonable degree of certainty about future trends of global average temperatures. In other words, projecting future climate change is an extremely difficult task. Identify some of the major factors, along with their feedback mechanisms, that contribute to this difficulty. Be specific.