The Scope 3 portion would require public companies that have set a greenhouse gas emissions target or goal that includes its supply chain emissions to disclose emissions generated from its supply chain.
"Scope 3 reporting is not ready for prime time. Full stop," Mr. Williams said. "There are companies that have done an excellent job of working to pioneer Scope 3 disclosures. Those companies are typically on the vanguard of disclosure as opposed to the rest of the business community for whom Scope 3 may not be a relevant metric or their investors may not be asking for that information."
The Chamber, in its comment letter, suggested Scope 3 disclosures should be entirely voluntary.
Ms. Martin said there's "a possibility" the Scope 3 provision will get "scaled back" in a final rule.
During his Sept. 15 testimony, Mr. Gensler was asked several times about Scope 3 and seemed open to adjusting parts of the proposal. "We're looking at the 14,000 comments, we're trying to balance this out," Mr. Gensler said. "The one thing is, is we have to ensure the public companies that are saying this or that about Scope 3 aren't, frankly, misleading the public."
The SEC in a final rule could potentially provide flexibility on how Scope 3 emissions are calculated and categorized or provide additional carve-outs for the types of companies that must provide the disclosures, Ms. Martin said.
The SEC's regulatory agenda calls for the publication of a final rule in October, but with the massive volume of comments received and delicate nature of the rule-making, sources expect a final rule in early 2023.
"When we get to the final rules, they're going to look in many respects, very different from the proposed rules," Mr. Littenberg said. "I don't think they'll be nearly as expensive in many regards."
Hazel Bradford contributed to this article.