Common wisdom suggests that greater climate-risk disclosure improves welfare. We show that this need not be true. A firm endogenously chooses whether to adopt a costly green project to maximize its stock price. When disclosure reveals the project's climate-risk exposure (``greenness"), mandatory transparency reduces green adoption and can lower investor welfare. Costly voluntary disclosure can improve outcomes relative to both mandatory disclosure and no disclosure by balancing information benefits against adoption incentives.  While information regulation alone cannot achieve the first-best,  pairing full disclosure with green subsidies can. We explore implications for adoption of abatement technologies and hedging with climate derivatives.