It seems unlikely that climate change itself will affect the energy supply chain (unless we consciously respond to it and make the necessary changes, as some places are doing). What may happen is an onset of more destructive, less predictable weather patterns, flooding, a change in the acidity of the oceans, and other unforeseeable consequences. I think that the more likely problems we’ll be facing are a disruption of food production (and food chains) and water shortages. If we’re smart, we’ll take it upon ourselves to try to reduce our dependence on fossil fuels now.
What may affect fossil fuel use more than climate change is the simple fact that fossil fuels are finite, and we’re burning through them very rapidly. Some people think we’ve already passed the moment of peak oil production. Most think it isn’t far away, if it hasn’t happened already. So we probably will see a return to more “primitive” lifestyles. Again, though, if we’re smart, we’ll try to transition now while we have more control over the conditions.
Also, johnpowell, many climate changes models predict a very rapid change. It’s hard to know exactly what to expect, but there’s reasons to think that baby steps won’t be adequate.