Wal-Mart and Asda’s ambitious announcement on Thursday to make its operations a whole lot greener by slashing 20 million metric tons of greenhouse gas emissions from its supply chain had the environmental watchdogs buzzing yesterday. Well, the buzz continues today, mainly because the giant retailers have invited the public, including some of its biggest critics, into the conversation.

Wal-Mart asked the Environmental Defense Fund, Clean Carbon Project and other eco-advocates, many of whom not too long ago were bashing the mega retailer for its massive carbon impact, to help devise the strategy. It also turned to Treehugger.com, at one time one of its biggest critics, to host the Q&A discussion surrounding yesterday’s announcement. Wal-Mart also explains its rationale for a greener planet on all of the social media channels it has at its disposal; on its YouTube channel and on its Facebook fan page it allows users to speak their mind. And they do. As one Facebooker, among many, challenges:

Walmart, your not a bad place to go, but you guys going green? I don’t really see it at any of the Walmarts around me…….. I can only imagine how much electricity one Super Walmart sucks down..

This is no doubt a contentious issue, but Wal-Mart is not sealing itself off from the public debate. Treehugger a few years ago wrote an essay that it’s getting harder to hate Wal-Mart, long considered a villain to local mom & pop retailers. Giving the public a chance to vent may yet still do wonders for its public image.