Elizabeth Warren and three other Democratic senators are calling on BlackRock Inc. chief Larry Fink to back a proposed law that would require public companies to reveal their exposure to climate-related risk.

In an open letter to him dated Tuesday and announced on Wednesday, they wrote: “If BlackRock plans to live up to the commitments you made, we hope that you will go further by endorsing the reforms laid out in the Climate Risk Disclosure Act, and require companies in which you invest to issue public disclosures consistent with its requirements.” The letter was also signed by Cory Booker, Chris Van Hollen and Sheldon Whitehouse.

Fink said last month that BlackRock, the world’s largest asset manager, will put environmental sustainability at the center of its strategy. It intends to divest from companies that pose a high sustainability-related risk, such as producers of thermal coal; to start investment products that screen fossil fuel companies; and to strengthen transparency in its investment stewardship. BlackRock, which manages more than $7 trillion, also joined a group of investors pressing the world’s largest emitters of greenhouse gases to curb pollution.

The senators asked Fink to detail any concrete measures his firm has already taken to meet its commitments, and they asked for a response by March 17.

A BlackRock spokesperson didn’t immediately return a message seeking comment.

The Climate Risk Disclosure Act, introduced in 2018, aims to expedite the transition from fossil fuels to cleaner energy sources and reduce environmental and financial risks.