Europe made big, bold promises to slash carbon emissions to slow global warming, but now the bill is coming due, and governments are starting to blink at the cost — political and economic — needed to power the great transition away from fossil fuels and toward renewables. Once far-off goals are getting more real, as Europe wrestles with how to tell Germans which cars they can drive, Italians which stoves are acceptable, Polish miners why they must abandon coal, and Britons why they can’t keep exploiting their country’s massive oil and gas reserves.