Just think about it though...
How much *MORE* carbon fossil fuels we could burn through... iffin we'd have thought about drilling and recovering hydrates.
In the mid to late 1800s, imagine drilling for oil... TOUGH TOUGH TOUGH. Probably no more tough than recovering gas hydrates if they'd have really know about them.
They'd have discovered a way.
We KNOW drill rigs have hit Hydrate Deposits before, as they nearly always BLOW UP when that happens. So it more accessible than we probably think.