What's the carbon footprint of email? -

What’s the carbon footprint of email?

What’s the carbon footprint of email?

(Sometimes the things you start to think about as you get more sustainability-minded just get odder and odder.)

A lot of people are surprised to hear that the ephemeral things like e-mail and “the cloud” have carbon footprints, but indeed they do. And while they may seem insignificant in the scheme of things (Apple says customer use is only 15% of an iPhone XS’s carbon footprint, whereas production is 81%), these tiny numbers begin to add up very quickly when we consider we send an estimated 281 billion e-mails every day.

The information communications and technology industry – think internet and cloud services – produces more than 830 million tons of CO2 every year. That adds up to about 2% of all global CO2 emissions and about 7% of the world’s electricity.

I share none of this with you to increase your anxiety about yet another thing to worry about, but simply to remind us all that zero waste goes far beyond a plastic bag. Being mindful in all areas of our lives is how we’ll reduce our carbon emissions most efficiently.

What's the carbon footprint of an e-mail? - Green Indy Blog

What’s the carbon footprint of email?

Spam e-mail: .3 grams of CO2
Regular e-mail: 4 grams of CO2
E-mail with large attachment: 50 grams of CO2

Statistics taken from “How Bad are Bananas?: The Carbon Footprint of Everything” by Mike Berners-Lee. While most of the statistics are probably still fairly accurate, the total/annual numbers are low since the book was written nearly 10 years ago.

Professionally, our e-mails are a big problem. A report prepared by the French Environmental and Energy Management Agency (ADEME) estimated that “professional emails generate an astonishing 13.6 tonnes of CO2 equivalent greenhouse gas emissions a year, or 136kg per employee. That’s equivalent to about 13 return journeys from Paris to New York.”

Personally, e-mails are also an issue. Berners-Lee estimated in 2011 that – on average – a year of e-mails adds up to around 300 lbs of CO2 emissions every year. (That’s like driving 200 miles in a car.) I’d wager that number is probably higher now.

Both of these numbers factor in spam – a sizable part of our digital carbon footprint. The average spam message (like a regular email) creates 0.3 grams of CO2. When multiplied by the estimated 62 trillion spam emails sent in 2008, that’s as much as driving around the Earth 1.6 million times. The good news is that McAfee estimates spam filters save 153 TWh of electricity per year which is the equivalent of taking 13 million cars off the road! (source)

“But,” I hear you asking, “where do those carbon emissions come from?”

The huge amounts of power data centers and computers need to use to send, filter, and read messages. (ADEME cites a fact that the average digital items (mail, download, video, web request) travels about 15,000 km before getting to your screen! source – FR

But really… why?

Let’s talk about where this CO2 is coming from – and why it’s significant – by looking at the two resources being eaten up by data centers: electricity and water.

What's the carbon footprint of an e-mail? - Green Indy Blog


Think about a facility that would have the ability to store a bunch of data. Even if you have no idea about the particulars (me neither), you can image there are a ton of boxy electronics, wires, and blinking lights keeping our e-mails accessible all the time.

Then think about the electric bill of your home – and then imagine what that bill would look like if you had around 10,000 large servers stored inside. So. Much. Electricity.

These massive data centers can be thought of as havens for “dormant pollution”, ie. stored e-mails make serves run uninterrupted despite not being actively used.

The impact of these dormant polluters are made so much worse since many of the major data centers are located in areas where renewable energy options are non-existent. Like just about 50 miles from where I grew up in Virginia. I grew up not far from this area hearing horror stories about Dominion but never knowing this was so close:

Most of us communicate with this small and wealthy corner of the US every day. Thanks to a combination of factors – its proximity to Washington DC, competitive electricity prices, and its low susceptibility to natural disasters – the county is the home of data centres used by about 3,000 tech companies: huge agglomerations of circuitry, cables and cooling systems that sit in corners of the world most of us rarely see, but that are now at the core of how we live. About 70% of the world’s online traffic is reckoned to pass through Loudoun County.


But there is a big problem, centred on a power company called Dominion, which supplies the vast majority of Loudoun County’s electricity. According to a 2017 Greenpeace report, only 1% of Dominion’s total electricity comes from credibly renewable sources: 2% originates in hydroelectric plants, and the rest is split evenly between coal, gas and nuclear power. (source)

Remember how an average piece of digital data travels – on average – 15,000 km before it reaches your screen? This is why. Companies are capitalizing on cheap electricity to place these facilities, not thinking about their impact. And since data travels so fast, there’s no real incentive to place data centers close to where people might need them.

A 2016 Greenpeace report reaffirms this: “The transition to the cloud could in fact increase the demand for coal and other fossil fuels despite significant gains in energy efficiency and adoption of a commitment to 100% renewable energy because of the dramatic growth in new data center construction by cloud and colocation companies such as AWS and Digital Realty in Virginia and other hot spots that have some of the lowest percentages of renewable electricity in the U.S.”

Because here’s the thing: companies can say they want to transition to renewable energy all they want, but if they build in locations where that option doesn’t exist… it creates a very easy loophole that lets them shrug their shoulders and say well, we tried.

What's the carbon footprint of an e-mail? - Green Indy Blog

The demand for electricity is growing

The same Greenpeace report estimates a massive expansion of energy usage (makes sense, right? None of us are slowing down how much we use the internet): ” Looking forward, global estimates of data center demand in 2030 anticipate an increase of three to 10 times current levels, with high end estimates of projected data center electricity demand alone reaching 13% of global electricity consumption.” Sadly, many of those companies that use the most energy are the worst rated in terms of sustainable energy.

Which companies are doing this well?

For all their other issues, it’s no surprise that massive companies like Facebook, Google, and Apple score well on their assessments. (They all ranked A in the 2016 report.) They’ve set 100% renewable energy goals, they’re remarkably transparent about the process, they have facilities in renewable energy hotspots like California, and they have money to throw at the initiatives.

Companies doing badly are Chinese-owned companies (while this article focuses mainly on US-issues, the problem is of course global) and streaming services. It’s significant – and environmentally dangerous – that streaming services like HBO (D), Hulu (F), and Netflix (D) are doing badly since they require so much energy. (But YouTubers be happy: it got an A with 56% of its energy coming from renewable resources!)

Significant because an energy researcher found in 2011, “Americans streamed 3.2 billion hours of video, which consumed 25 petajoules of energy and resulted in 1.3 billion kilograms of carbon dioxide emissions, according to his 2014 report. He said those numbers have likely soared over the past six years.” Yikes.

See how large companies break down in the Greenpeace report – check out pages 8-13 for the ranks of some major online companies.

What's the carbon footprint of an e-mail? - Green Indy Blog


It may seem surprising to see water pop up here; after all, it’s hard to imagine what water has to do with internet services. Turns out, a lot.

With all the energy being used for the almost 3 million data centers in the US alone, they require huge amounts of water. They use the water directly to cool the servers, which heat up from being in use 24/7, and indirectly from water being used in the same way at the power plants they get their electricity from.

A data center designer and researcher at Amazon even admitted the problem is dire: “‘Water is tomorrow’s big problem,’ Hamilton said. ‘No one talks about water. The water consumption (in data centers) is super embarrassing. It just doesn’t feel responsible. We need designs that stop using water.'” (source) This was in 2009 and he estimated that a 15-megawatt data center can use up to 360,000 gallons of water a day.

Extrapolate that to the around 3 million data centers in the USA and the numbers become basically unfathomable. “US data centers were responsible for consumption of 626 billion liters (165 billion gallons) of water in 2014, which includes both water consumed directly at data center sites and water used to generate the electricity that powered them that year. The researchers expect this number to reach 660 billion liters in 2020” (source).

With a world in which water is going to become more and more scarce, we need to critically evaluate whether such use makes sense. If not, this leads to a whole different host of questions about what our world will look like if we’re required to radically re-imagine it.

What's the carbon footprint of email? -

How to reduce your online carbon footprint
  • Be proactive about maintaining a small inbox. Remember that those e-mails from last year aren’t just sitting in your inbox, they’re requiring energy to store them on servers. Delete, delete, delete! (And unsubscribe from unnecessary newsletters to lessen your work next time!)
  • Stop sending unnecessary messages. Feeling lazy so you just shoot a message to someone nearby? Stop! When possible, avoid messaging and communicate face-to-face. This helps build a stronger relationship and avoids putting more strain on data centers.
  • Support companies that use renewable energy to power their cloud. This can be difficult as these companies are practically monopolies . But, for example, if you run your own website, consider using the carbon neutral GreenGeeks like I do! But be sure to do your research – these companies are absolutely trying to greenwash their practices. Like Amazon Web Services (AWS), for example: “Green campaigners bemoan the fact that the details of AWS’s electricity consumption and its carbon footprint remain under wraps; on its corporate website, the story of its use of renewable energy suddenly stops in 2016.” (source)
  • Avoid vampire power. When your computer’s turned off but you’re still plugged in and charging, your device will draw .5 to 2 watts of energy per hour. Not a lot, but still… it all begins to add up. Make sure to unplug all electronic devices when not in use to conserve power.

Again, none of this is to put you in a shame spiral of “oh no, one more thing to worry about!”. This post is simply to bring awareness to the fact that all facets of our life are inextricably linked to resource consumption and living sustainability. Consume thoughtfully!