Ten tons!
Ten tons of CO2! That's 2.5 tons of carbon, so a bit more in terms of fuel weight, about 20%, so 3 tons of fuel burnt.
In extreme duration flights a 777-200LR carries up to ~280 passengers with up to ~180 tons of fuel, so unless my numbers are way off, you're out by a factor of about 4.5, if the flight's full.