Here’s another one to file under Bigger Deal Than It Seems.

A little over a year ago, I wrote about N.Y. Attorney General Andrew Cuomo’s effort to pressure energy companies into fully disclosing their carbon risk. He sent them subpoenas which said, among other things:

Any one of the several new or likely regulatory initiatives for CO2 emissions from power plants — including state carbon controls, EPA’s regulations under the Clean Air Act, or the enactment of federal global warming legislation — would add a significant cost to carbon-intensive coal generation. … Selective disclosure of favorable information or omission of unfavorable information concerning climate change is misleading.

Now Dynegy, one of Big Coal’s key players, has agreed to disclose.

What happens next? How will Dynegy go about assembling the information? How will they reveal it? What will happen to their stock price afterward? Who will be forced to disclose next?

A great deal hinges on the market honestly grappling with the externalized risks and costs of fossil fuel energy. This is a big step in that direction — will be interesting to watch.