Burning it at the source means thatuch more gas will also be extracted and (ultimately) burnt for the other use.
2xNH3 -> 3xH2 + N2 is fine, only excepting that more NH3 will need to be made. In the future it will be made with wind or solar energy, but that is still a few decades off.
It persists in atmosphere shorter than CO2 though, so a 100 year coefficient is 28x.
Source: https://climatechangeconnection.org/emissions/co2-equivalent...