I can't speak for the intention of the person who wrote the amendment. I think it should have an “s” on it. That's the way the term has been used in the rest of the bill, so it would be consistent. I think there should be consistency throughout the bill.
Just to be clear, the terms are used interchangeably. The reason “emissions” is used is either because of a reference to emissions from multiple sources or because there are multiple different types of greenhouse gases, plural, which can be combined into emissions, plural.