Both kinetic energy and air friction scale approximately with N^2. (Where N is units of velocity.) One can escape a lot of air friction by going higher, which is what Boom is planning to do, but you have to pay for the potential energy of altitude with fuel. Boom is minimizing the weight by using carbon fiber. (Which also means the wings have to redirect less air to keep the plane in the air, which also reduces drag.)

It's likely that the carbon footprint is several times higher, perhaps nearing an order of magnitude.