Hi Scott, it’s a good question - I assume the answer is no, they do not include leaks from the collection and distribution system, unfortunately these are assumed to be outside of scope. Leakage rates above ~3% make methane worse than coal over 100 years, the situation is even worse if we consider a shorter timeframe such as 20 years. Current leakage rates vary by estimate, the industry’s own estimates are often used by government, but independent checks have found them to be much higher, e.g., this study from Stanford found the fields in New Mexico to be leaking at a rate of 9%.
Ideally a drastic reduction in demand and use of plastics, as well as the burgeoning algae based biopolymer industry will help to end fossil fuels.