Probably metric tonnes, but it's weird to use "Mt" to mean metric tonne rather than megatonne. The symbol for metric tonne is "t" [0]. It would certainly be les

Probably metric tonnes, but it's weird to use "Mt" to mean metric tonne rather than megatonne. The symbol for metric tonne is "t" [0]. It would certainly be less ambiguous to just spell it out. [0]: https://en.wikipedia.org/wiki/Tonne https://en.wikipedia.org/wiki/Tonne