Driving this 15,000 miles a year would release about 12.2 metric tons of CO2 annually. That's equivalent to a couple going on a single roundtrip flight from California to Europe: https://flightfree.org/flight-emissions-calculator.
Judging by my Facebook, I know a lot of sociopathic assholes. :-/
At these rates and a great circle distance of ~8000km you'd get 4 metric tons for two people round trip. Long-haul planes are likely more efficient than average per passenger mile, so some SFO-LHR round-trips are actually closer to 1 metric ton per person. Still not great, of course.
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Judging by my Facebook, I know a lot of sociopathic assholes. :-/