Here's the asterisk for Mark Zuckerberg's post about Facebook's carbon footprint and lattes

In honor of Earth Day, Facebook CEO Mark Zuckerberg posted on his timeline that your Facebook use for an entire year has a smaller carbon footprint than making a latte:

Well, that phrasing isn't entirely fair.

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Here's the much more accurate way that Facebook talks about the same stat when it's showing off its data-center technology:

Facebook

Business Insider snapped this picture while checking out a Facebook data center pop-up exhibit.

For Facebook, the emissions per person from its data centers have a smaller carbon footprint than the latte. And indeed, Facebook has made great strides in making its data-center operations much more efficient.

But technically one person's yearly Facebook use has a higher footprint because it also includes the emissions from whatever electricity-draining device they're using to scroll through their stream of vacation pictures, humblebrags, and news links.

The world could generate 13 megatons of greenhouse gases from smartphone charging by 2019, Juniper Research predicted. Energy-wise, that is a lot of lattes.

Facebook, for its part, has invested a lot of resources in making its data centers as efficient as possible, even making tiny tweaks to ensure that they require as little energy as possible. For example, it doesn't put plastic bezels in front of its servers, as per common practice, because, without them, each server can draw in more air to cool itself.

Facebook's custom data center in Prineville, Oregon, uses 38% less energy than its other facilities while costing 24% less.

And using Facebook's services does, for example, use less energy than printing out those photos or reading those news articles in print.

To learn more about Facebook's carbon footprint, you can read about how it breaks down here.

But, before you pat yourself on the back about how little you're hurting the planet because of your Facebook addiction, it's worth also thinking about ways you can make a really big difference by changing your driving habits - or perhaps even using your phone less.