On the whole I'm strongly in favour of air travel - at least, I'm strongly in favour of at most one-level-vicarious personal experience of strange far-off places, and air travel is the only realistic way to get anyone there; going over land to Bangkok is significantly more expensive than Thai Air even if time and ludicrous inconvenience are not a constraint, the price of the return plane ticket won't get me a train beyond about Moscow.
Yes, it takes a lot of energy to remove one ton of CO2 from the air: http://nextbigfuture.com/2009/06/co2-removal-from-atmosphere.html says fifty kilojoules per mole which is 1.2 gigajoules per ton, http://www.futurepundit.com/archives/005592.html is optimistic and says a third of that.
A gigajoule is about 300 kilowatt-hours, so about thirty pounds worth of electricity at the price I pay for it as a domestic user on a not-terribly-good-value tariff. Say the cost-of-capital and depreciation for CO2-removal equipment is about the same as the electricity; so the total cost for taking CO2 out of the atmosphere would be sixty pounds a ton.
Even people strongly against CCS no-net-CO2 coal-fired electricity generation argue that the efficiency cost of doing the CCS would be about 30%, the currently-4GW facility at Drax would produce 2.5GW; say this doubles the price of the electricity and we're talking a hundred pounds a ton.
One of Easyjet's A319 planes burns 850 gallons of fuel an hour to transport say 120 people (capacity is around 150); jet fuel produces about a ton of CO2 per hundred gallons burned, so taking your 120 people two hours to Berlin has produced about twenty tons of CO2. Removing which would put £17 a head on the cost of the flight; Easyjet is nothing if not cheese-paring, so it probably wouldn't put £30 a head on the price of the ticket. +30%. The last time I compared the prices, Easyjet to Berlin was £100 return and rail was £400 one way.
A Eurostar train carries 750 people two hours from London to Paris and uses 12.5 megawatts of electricity to do so; 25 megawatt-hours at a kilo of CO2 per kilowatt-hour for UK electricity generation [yes, I know most of the French electricity is fission-produced] is 25 tons, so about the same amount of CO2 as the A319 to get six times as many people about half as far. I don't have the figures for slower trains.
A 747 with its 400 passengers burns about a gallon of fuel a second, say produces 36 tons of CO2 per hour, it's eleven hours to San Francisco so that's 400 tons, £24000 to remove. A hundred pounds per passenger per direction; say £250 on the price of the return ticket. +30% again, maybe a bit worse if you're flying at very off-peak times and can get a cheaper base ticket.
Flights aren't the overwhelming part of the cost of foreign holidays now; making them 30% more expensive doesn't seem likely to stop people travelling, and if doubled electricity bills and somewhat more expensive holidays are the price I have to pay to keep London (and incidentally Bangladesh, for there is only one sea level) above water, I'll pay gladly.