Methane, the major constituent of LNG, is an extremely potent greenhouse gas. When coal escapes, you have a black rock on the ground. When natural gas escapes, it fucks up the atmosphere real bad. And it escapes a lot along the supply chain. These are called fugitive emissions and iirc companies are not even required to keep track of them.

The amount of energy required to liquefy and ship natural gas across the ocean is horrendous, it’s almost certainly more emissions than locally mined coal in England or whatever.

This carbon stuff is always funny math though, like on a straight btu basis gas is much cleaner but probably not when you include transportation. In fact the retirement of coal plants in favor of combined cycle gas has been a huge driver of CO2 emissions reduction in the power sector.