According to the Chicago Climate Exchange, carbon offsets are currently selling for 10c per tonne. I used the carbon offset calculator at the Qantas website and it calculated that my upcoming holiday will generate 1.452 tonnes of CO2. Qantas want to charge me $13.80 for this. However, that would cost me US$0.14 if I bought offsets from the CCX. A further question might be why Qantas is charging 100 times the going rate for carbon offsets.