Well, the answer is both in effect, because there is more than just oil to consider.
Currently our food, transport, materials (plastics etc) are inextricably linked to the use of petroleum based products, this is the non-renewable resource which we are likely to find becoming increasingly costly and scarce in the near (<20 years) future. There is still a LOT of it in the ground, with a lot of CO2 to release into the atmosphere, but our consumption is still growing, and we burn more of it per day than at any time in the past. Of course the peak oil debate would lead us to believe that our growing consumption will be constrained by our ability to extract it, but in any case it is oil which we are likely to lose as the ubiquitous and cheap energy source we exploit so extensively today.
Arguably of far greater concern for its potential effect on climate change is coal, which as we use it today is a massive polluter and contributor to greenhouse emissions. There is an awful lot of coal still in the ground, there is a risk it will continue to be exploited to provide cheap energy even as we see its effects on our climate and environment.
I think the most worrying thing at the moment is that we as a population don't seem to appreciate that we are consuming non-renewable stored energy at a prodigious rate and at low cost today, and it is only through this cashing in of the earths stored solar energy that we are able to maintain our modern way of life.
We don't have a set of viable alternatives which are renewable currently, which can provide the same levels of energy at the same costs. The return per dollar spent in terms of energy in petroleum has been the driving force of modern civilisation for 50 plus years, we can't get anything like that kind of efficiency out of any other form of energy production today, so we better keep working on those alternatives, or we're going to have to face the consequences.