"Throughout our environmental journey, we've emphasized the importance of measurement and reporting to help us understand our impact," said the letter, signed by Apple's director for state and local government affairs D. Michael Foulkes, a copy of which Senator Scott Wiener posted on Thursday to X, formerly known as Twitter.
Wiener's bill would require public and private companies with annual revenue in excess of $1 billion who do business in traditionally climate-conscious California to disclose independently verified data on their planet-warming emissions.
"Thank you, Apple, for making clear that this is doable (and) a critically important piece of climate action," Wiener wrote.
Apple did not immediately respond to a request for comment.
The top U.S. securities regulator is yet to publish a long-awaited rule of its own on climate-related disclosures, and California senators are going ahead at the state level.
A separate bill under discussion would require companies operating in California, with $500 million in revenue, to report on climate-related financial risks such as whether they have budgeted for increased compliance and insurance costs.
Together, the bills could affect thousands of companies.
Groups including Adobe (ADBE.O), Ikea and Microsoft stated their support for Wiener's bill in a letter addressed to California officials in August, according to a copy posted online by activist group Ceres.
In its letter to Wiener, Apple commends his bill's attempt to require companies to measure and report indirect emissions linked to their supply chains and end-users, known as Scope 3.
Noting that the legislation currently leaves open the date by which Scope 1 and Scope 2 disclosures - which relate to emissions from operations and those associated with a corporation's energy use - Apple suggests "leaving sufficient time for data collection, quality control, and third-party review".
