In what apparently marks one of the web’s fastest-growing environmental campaigns, Greenpeace International has revealed that Facebook users have joined the movement that is urging the popular social network to dump its plans of buying electricity from a coal-based energy company for its new US data center.

Greenpeace, the Amsterdam-based environmental group, initiated the Facebook campaign in February, following the social network’s announcement of its plans to build a data center in Oregon.

The total members of the Greenpeace-backed groups, which have been requesting Facebook to use 100 percent renewable energy, last week surpassed a collective 500,000 – which is, incidentally, only a small fraction of Facebook’s over 500 million users round the world.

With the campaign catching on, Greenpeace International’s Executive Director Kumi Naidoo warned Facebook founder Mark Zuckerberg in a Wednesday letter that in case the company chooses to overlook the environmental effects of its actions, it will put at stake not only its reputation, but also its financial health.

Naidoo said in the letter that Facebook is “uniquely positioned to be a truly visible and influential leader to drive the deployment of clean energy.”

Though Facebook has refrained from making any specific mention of the amount of electricity that it uses for storing information, streaming video, and connecting its 500 million users, industry estimates reveal that, based on their current growth rate, all the data centres and telecommunication networks worldwide will likely consume nearly 1,963 billion kilowatt hours of electricity by 2020.