Imagine a world without a subsidized fossil fuel industry

I was intrigued and annoyed by an article by a philosophy professor arging that "progressives" should not be in favour of carbon taxes, largely on the grounds that they are regressive (i.e. they disproportionately hurt the poor), and that the rebates governments offer to make up for the imposition of such taxes are not able to make up for this unfairness. It was a reasonably well-argued article, even if I didn't agree with it all, and even if the fact remains that revenue neutral carbon taxes are still the best market-based tool we have to change behaviours and fight climate change.
The intriguing part of the article was the idea that, instead of imposing carbon taxes, we should be stopping the wholesale subsidizing of the fossil fuel industry by governments. While I would agree with this in principle, I disagree that this aproach should take the place of carbon taxes. They are two complementary parts of the puzzle, as I see it.
The article coincided with the announcement of the International Monetary Fund (IMF) that worldwide fossil fuels are subsidized by governments to the tune of $5.2 trillion annually in 2017, a truly astounding sum representing about 6.5% of global GDP (and up by about half a trillion dollar from two years earlier).
A little more analysis, though, shows that only $ 296 billion - I say "only"! - of this sum is what we normally think of as subsidies, what the IMF calls "pre-tax subsidies": i.e. the difference between what people pay for fossil fuels and their actual costs to produce. Most of this is in the form of subsidies to help consumers buy fossil fuels, with a lesser amount coming as help for companies to extract and process the fuels.
The other 94.3% of the IMF's $5.2 trillion figure is made up of what it calls "post-tax subsidies" - what I would refer to as externalities - the costs of air pollution and the effects of climate change, traffic fatalities, and the depressed tax base as a result of the fatalities. It is an admirable belt-and-braces attempt at establishing a total cost, but it is based on a whole host of assumptions, and very difficult to estimate and justify.
The $296 billion figure, though, is incontestable, and it is still a very large amount. Imagine if that subsidy were withdrawn and people were faced with the real costs of a litre of gasoline. There would certainly be an awful lot more hybrids and EVs on the roads! Interestingly, though, government subsidies of the fossil fuel industry are on the wane. Total subsidies in 2012 ($572 billion) were almost double the 2017 figure. Several countries in the Middle East, of all places, have recently slashed their subsidies. 
Still, it's interesting to imagine the effects of withdrawing all government subsidies for fossil fuels. Don't hold your breath, though.