[Steely Tom]

Where do they get the carbon?

[Paladin2]

One could get it from the exhalations of the crew, or from following oil burning ships, or the ever increasing concentration in the Atmosphere (CO2 is also dissolved in the Ocean).

[Hostage]

CO2. There’s lots of CO2 dissolved in seawater. In fact oceans are a huge sink for CO2, which of course our esteemed Gore-certified climate changeologists ignore.

[norwaypinesavage]

"Where do they get the carbon?"

From the same source as they get the energy---magic. Obama has used his pen and phone to overrule the First Law of Thermodynamics.