To be a pedant it might be a plurality (biggest one), but not a majority (>50%)

if it has a pareto distribution, isn't that sort of tautological? If they eliminated all of those those sites, they'd reduce emissions by 46%, but of the remaining, wouldn't the top .2% still be producing roughly 50% of emissions?

It depends on how you define a "handful" (which is a terrible term in that context, we're not talking about hazelnuts..). But for sure 46% isn't "the vast majority" of anything.