 If we have a look at what happened over the last 170 years, we can see that post 1850 temperatures were still in the Holocene. They were still hovering along but the Industrial Revolution kicked in just shortly after that and our temperatures slowly started to increase. Temperature is a measure of the internal energy of a system. And increasing temperatures, like we are seeing, suggests that the internal energy of the atmosphere is increasing. And if that's the case, climate change is simply a response to changing energy levels. So the next step in understanding climate change is to understand how energy drives the system and therefore how energy drives climate. Physics knows a great deal about the fate of energy in our earth atmosphere system and we understand how these processes work.