40% of the electricity globally is generated by coal. https://en.m.wikipedia.org/wiki/World_energy_consumption#Electricity_generation https://en.m.wikipedia.or

40% of the electricity globally is generated by coal. https://en.m.wikipedia.org/wiki/World_energy_consumption#Electricity_generation https://en.m.wikipedia.org/wiki/World_energy_consumption#Ele... 80% is fossil fuels. I’d be more worried about their daily electricity usage than one or two flights a year.