This paper shows evidence of a positive relationship between institutional dual holders, who hold both equity and debt in a firm, and voluntary greenhouse gas (GHG) emission disclosure. Considering dual holders as particularly risk-sensitive institutional investors, we document that voluntary GHG emission disclosure improvements are motivated by not only climate-conscious but also risk-related considerations. The positive effect of institutional dual ownership is more pronounced when firms face severe environmental risks, where disclosure enables explanations and prevents exaggerated stakeholder reactions. The impact of dual ownership is also stronger in firms with poor information environments, where dual holders exploit their salient monitoring capacity from gathering information from their public equity and private debt holdings. Supporting our risk-based explanation, voluntary GHG emission disclosure reduces the cost of equity and increases firm valuation in firms with higher dual ownership.