The Securities and Exchange Commission has decided to add climate change to the already long list of risks companies must disclose to investors, after a prickly hearing and sharp disagreement among the commissioners about whether such disclosure is really practical.

The Commission voted 3-2 to publish interpretive guidance on what it expects public companies to disclose in Form 10-K about climate change risks, with Chairman Mary Schapiro and her two fellow Democratic appointees in favor and the two Republican nominees opposed. The agency has not yet published a text of the guidance, nor is it clear when the guidance will be ...