For the past two centuries we've been digging up coal and burning it. We've burned coal for space heating--far more convenient than firewood!--and to fire steam boilers for locomotives, pumps (first, to de-water the coal mines and get even more coal), power turbines, and smelting steel.
For over 100 years we've been drilling oil and then gas wells, piping the gas to market (heating, industrial processes, fertilizer), and refining crude oil to gasoline, kerosene, and heavier oil, while burning the oil distillates in cars, trucks, SUVs, motorcycles, taxis, buses, ships, trains, planes, tractors, ATVs, jet skis, dragsters, Indy cars, rally cars, funny cars, monster trucks... A lot of 'sports' entertainment relies on the excitement value of seeing which powerful gasoline engine will carry which daredevil competitor the fastest--or jump the farthest over other, less gigantic vehicles. I looked at photos and TV shows of a whole lot of these internal-combustion powerhouses. Every boy in my school drew pictures of 'cool' cars, and collected HotWheels(TM) toy cars. The coolest of all had to be Sizzlers - tiny battery-powered speedsters we raced around the FatTrack(TM) until they needed recharging. (Hey, electric vehicles in the 70's!)
The fossil fuel sector is an historic stand-out: it transformed our global society into a hyper-connected, always-on-the-move rat race/traffic jam. Today we routinely catch flights halfway around the world, hop 14-storey cruise ships (all you can eat!), and order a lot of stuff online which was built far away, perhaps shipped by vast container ship, rail and/or tractor-trailer to the Giant Warehouse. Then it was packaged up just for us, barcode labelled and dispatched to us - perhaps by air freight, then onto a delivery van right to our door (or if you still go to 'stores,' the whole chain still worked to get your cornucopia of products onto the store shelves.)
Think of how many internal combustion engines were needed in that supply chain--then consider how many times a day items are loaded up and sent via whatever fossil-fueled vehicle. There are now well over a billion internal combustion engines worldwide--hundreds of millions of passenger and freight vehicles, plus tractors, mowers, pumps, generators, ...
Modern civilization is exquisitely dependent on the internal combustion engine.
Is this a problem?
Two distinct issues arise when we reflect on the vast scale and breathtaking rate of growth of the fossil fuels and the hardware in which we burn them: 'peak oil', and the greenhouse effect. I'll get into the issue of greenhouse gas emissions later; here, let me first focus on fossil fuel limits. First, these resources cannot be infinite, and a day must come when we can no longer go on increasing the volume produced. This is summed up in the concept of 'peak oil': that we must face the inevitability that the earth will eventually stop yielding as much oil (and gas and coal) as we have been demanding. The best case for geological limits on oil extraction that I've seen is Ken Deffeyes' book Hubbert's Peak. Here's a good review of Deffeyes' recent work. The website http://peakoil.com/ offers readers plenty of info on this viewpoint.
For a while, the concept of peak oil started to take root, impacting investors and even the world of policy. But it has always been held at bay as a 'fringe' movement. The powerful fossil fuel sector wanted no part of coming to terms with this, and free market fundamentalists clung to the blind faith that whatever we are going to need in the future, the 'magic of the marketplace' will always deliver it, somehow. Talk of ultimate limits remained anathema to this mindset.
Many more of us, mostly not wedded to such extreme ideology, still choose not to take the step back to look at these questions. The economy is ticking along, utterly reliant on ever more oil wells. It has to work. Don't ask me whether future generations will have the luxury of carrying on burning fuels as we've always been able to do -- too much for me to think about!
After a brief spell of very high oil prices, where it appeared that the 'peakers' may have been vindicated, oil prices fell as hydraulic fracturing methods came into play on a large scale. The U.S. is less dependent on imported oil than it has been in many decades.
One might try to point out that this new technique only delays the inevitable reckoning; that 'fracking' for oil is a lot more intrusive and disruptive to local residents, and it too must at some point hit a peak beyond which it can grow no further and must over time start to decline. So far, though, the extra time that fracking has bought the U.S. has pushed these considerations far off the front page, or the top-of-mind. Trump's EPA Administrator Scott Priutt feels justified in seeking to cancel established regulations setting fleet fuel economy improvement targets for the coming years. Go ahead, keep making and driving gas guzzlers -- we'll just keep fracking til we've got wells on every block.