It isn't a government agency, it's just a coalition of large businesses in the US. Really, it's a lobbying organization for these businesses. The US Chamber of Commerce position on climate change has been very regressive, and quite a few companies have started to take notice of it.
But now it is getting serious. Apple has quite the Chamber (as have other companies recently). [LINK] Note that Apple isn't the first company to do so, their move follows some others, which amazingly also include some big utilities [LINK1, LINK2].