Singh says in her article:
Lowest amount of carbon emitted by a single email = 0.3 g Highest amount of carbon emitted by a single email = 50 g (!!!!) If we multiply this by the rate of 2.4 million/sec, Amount of carbon emitted per second would lie between 720,000 grams and 120,000,000 grams. The real answer definitely lies in this range.
And Angela Mollard says:
Storing 1GB of email consumes about 32kWh of energy per year and I have 6.29 GB of stored emails which means mine are gobbling up nearly 200kWh of energy.
As a numbers person I have designed numbers for 20 years for GM/Opel. I "grok" numbers. You need to make sure that the numbers you present make sense. You also need to make sure that you can show how you calculated your numbers. Otherwise, the numbers aren't worth anything.
Finding the source
The Radicacti group (wonderful name!) makes expensive reports on emails. One report says:
The total number of business and consumer emails sent and received per day will exceed 293 billion in 2019 and is forecast to grow to over 347 billion by the end of 2023.
That roughly fits with the data of 2.4 mio emails per day. You need to divide the daily number by the seconds in a day. Unfortunately, the Radicacti persons don't say how they got the number. Crystal ball? If they measured something, what did they measure? Did they extrapolate something?
Then I did a bit of goggling to find the source of the data for grams carbon by email. For instance according to twosidesna.org:
The footprint also reflects the kind of energy used by the infrastructure which allows that email to be sent. Data centers, for example, store our emails along with all their attachments, photos etc. In 2014, data centers in the U.S. consumed an estimated 70 billion kWh or about 1.8% of total U.S. electricity consumption. Data centers require a lot of electricity because rooms full of servers generate heat that must be cooled if the servers are to be kept running. This cooling comes from large air conditioning systems which vary widely in their source of energy and efficiency; it could be coal-fired power plants or renewable energy (like hydro, wind or solar) or some mix of both. This affects the footprint of the email that travels through that data center.
That makes sense. But how large is the carbon footprint of a single email?
The original numbers of the 0,3 - 50 gram/email CO2 comes from a book by Mike Berners-Lee: How Bad Are Bananas - The Carbon Footprint of Everything. In this book he lists - as the title says - how much carbon different things cost. From a text message to oil spills. The figure for emails is from a report by McAffee that I wasn't able to find.
What I was able to find were at least a half a dozen articles in the interweb who quoted either the book or the non-existing report!
What does this tell you? If you are a journalist make sure to read the original text.
Save the planet some other way
If you are concerned about storing your emails in data centers then off-load them to Mail Archiver. The local storage doesn't use much extra energy. And no, I’m not going to calculate the value
PS: Did you know:
- The more CO2 you have in the atmosphere the less fires you get.
- And the better the plants grow.