288 - Email Carbon | Scoins.net | DJS

288 - Email Carbon

I have come across several versions of a calculation showing the carbon footprint attached to an email and would like to address that as an issue.

The argument, as far as I can tell, originated with Mike Berners-Lee at Lancaster University (yes, that family; yes, pretty local). The thinking goes like this: you are using a computer and it has a carbon footprint. You are using electricity to power your computer, which has more carbon footprint. Just counting the CO₂ produced, we are anticipating around 4g of CO₂ per email. Obviously this is much worse if you're attaching pictures. Several arguments on the topic point also to the infrastructure that is required to keep the internet going, specifically server farms and their energy demands. Source [2] suggests the internet is responsible for around 2% of global emissions. That, says [4], exceeds the footprint for global air travel.

Many sources agree with this figure, but it seems that all connect back to a single source. Quite a lot of this tale could already be fairly accused of multiple counting, that is, counting the same consumption several times under different headings. Yes, we're consuming electrical power and yes, we're using our computers. But we would anyway, so it is not the email at fault, until we look at the additional storage and extra costs created by the traffic. Putting that in other words, if you're going to use your computer for a few hours, that usage—let alone the computer itself—has carbon costs attached; therefore it matters very little that what you did was an email. However, if we observe that very many emails are being generated and sent and dealt with at our receiver end (even if that is Delete), this is using facilities that could be being used for something more useful. Though all is relative. 

Many ask, quite correctly, whether—the extent to which—the sending of emails is necessary; I came across a suggestion just this week that we should stop sending texts that simply say "Thanks". I disagree, not that I do much thanking myself, but surely the waste lies in spam. I clear out more than 100 mails a day, but I don't think that uses as much electricity as in making a single cup of coffee and I suggest that my coffee (just in heated water) per day exceeds my computing per day quite significantly in terms of carbon footprint.

Source [5] says Brits send more than 64m unnecessary emails every day, and that if every adult in the UK sent one fewer “thank you” email a day we would save more than 16,433 tonnes of carbon a year – equivalent to 81,152 flights to Madrid or taking 3,334 diesel cars off the road. ¹

The pie charts (top of page until I find something better for a reference pic)  support the contention [7] that data centres already account for around a quarter of the energy consumed (and the carbon emitted) by the information and communication technology (ICT) sector as a whole. In other words, around half a percent of global CO2 emissions.

Tracking down the detail of the calculation is quite hard. ‘Brits sending 1 less email a day would save 16,433 tonnes of carbon a year’

  • x1 email = 1g carbon = 0.000001 tonnes CO2e per email (Source: Mike Berners-Lee)
  • 365 days per year / 12 months = 30.417 emails per month [this is days per month, one email a day]
  • 0.000001 tonnes of CO2e x 30.417 emails per month x 12 months per year = 0.000365004 tonnes CO2e saved per person, per year 
  • UK population of 52,351,213 adults (18 and over. Source: ONS)
  • 87% of adults use the internet daily and 86% of all adults use email (Source: ONS)
  • 86% of 52,351,213 = 45,022,043
  • 45,022,043 adults x 0.000365004 tonnes of carbon saved per person per year = 16,433 tonnes of carbon saved per year by total UK population

It is this first item that is giving me problems tracking down  x1 email = 1g carbon = 0.000001 tonnes CO₂e per email (Source: How Bad are Bananas?, Mike Berners-Lee). [9, 2010] gets us a little closer, but I note that the 'cost' has come down dramatically in 9 years. According to research by McAfee,² a remarkable 78% of all incoming emails are spam. Around 62 trillion spam messages are sent every year, requiring the use of 33bn kilowatt hours (KWh) of electricity and causing around 20 million tonnes of CO2e per year.

McAfee estimated that around 80% of this electricity is consumed by the reading and deleting of spam and the searching through spam folders to dig out genuine emails that ended up there by accident. Spam filters themselves account for 16%. The actual generation and sending of the spam is a very small proportion of the footprint. 

Spam [11]

• A year’s email at a typical medium-size business uses 50,000 KWh; more than one fifth of that annual use can be associated with spam

• Filtering spam is beneficial, but fighting spam at the source is even better. When McColo, a major source of online spam, was taken offline in late 2008, the energy saved in the ensuing lull — before spammers rebuilt their sending capacity—equated to taking 2.2 million cars off the road.

Spam is 80% of all email.

The average GHG emission associated with a single spam message is 0.3 grams of CO₂. 

Although 78% of incoming emails sent are spam, these messages account for just 22% of the total footprint of a typical email account because, although they are a pain, you deal with them quickly. Most of them you never even see. A genuine email has a bigger carbon footprint, simply because it takes time to deal with.

The average email has just one-sixtieth the footprint of a letter, according to a back-of-the-envelope comparison. That looks like a carbon saving unless you end up sending 60 times more emails than the number of letters you would have posted in days gone by. Lots of people do. This is a good example of the rebound effect — a low-carbon technology resulting in higher-carbon living simply because we use it more.

There's a general issue here; Mike B-L has produced a number and everyone is happy to copy it and play with the results, but not to share the detail by which the original number was generated. [10] is typical of this. Actually, How Bad are Bananas? fails to explain itself too, which you might see for yourself at [14]. Pages 243-7 explains that the calculations are hard, but honestly, I'd like a single example worked through so as to have a feel for the certainty of any figure.

One of the helpful figures comes form [15], Google themselves, via [14]:

Recently, though, others have used much higher estimates, claiming that a typical search uses "half the energy as boiling a kettle of water" and produces 7 grams of CO₂. We thought it would be helpful to explain why this number is *many* times too high. Google is fast — a typical search returns results in less than 0.2 seconds. Queries vary in degree of difficulty, but for the average query, the servers it touches each work on it for just a few thousandths of a second. Together with other work performed before your search even starts (such as building the search index) this amounts to 0.0003 kWh of energy per search, or 1 kJ. For comparison, the average adult needs about 8000 kJ a day of energy from food, so a Google search uses just about the same amount of energy that your body burns in ten seconds. In terms of greenhouse gases, one Google search is equivalent to about 0.2 grams of CO₂. The current EU standard for tailpipe emissions calls for 140 grams of CO₂ per kilometre driven, but most cars don't reach that level yet. Thus, the average car driven for one kilometre (0.6 miles for those in the U.S.) produces as many greenhouse gases as a thousand Google searches.

So the numbers buried in there suggest 1kJ approximates 0.2g CO₂. I found an emissions calculator, [16], which told me that 1 GJ of diesel produces 70kg CO₂, so 1 kJ (a millionth of 1GJ), produces 0.07g. this tells you quite a lot about Google's estimates of power consumption, since the same calculator has that  1kJ of electricity equates to 0.04g carbon. Which is already 20% of the figure Google reckons for it's search. Well, this is in the right order or magnitude, but I can't say any better than that.

I also note that the carbon footprint of yourself is around the same as the processing of a search, since I doubt we react at all quickly: Type in request for search, wait, see there is a response, attempt to read enough to decide what to do next — quite easily the ten seconds-worth of computing used by Google for the search result.


I have been amused that one apparent result of recognising climate change, in the sense that we are possibly able to identify a trend—though it is also true that trends are hard to genuinely recognise early—is that we would appear to have need to reduce our personal travel dramatically. Which in turn rather suggests that the old idea of something like a village, your locale, is a good idea. Your locale therefore becomes the provider of what it is that you think you need (perhaps, want), and in turn you are relying upon others to transport a variety of stuff from far away in some efficient manner so as to reduce overall costs. Instead of having delivery to your door, delivery is to some very local point, probably within walking distance, so that either you go fetch for yourself or some neighbour (previously known as postman or delivery boy) provides the last link in the chain. All of this is good for society, given a measure of trust and co-operation, both of which strike me as desirable things. Meanwhile the internet serves to remove the need for significant physical travel for many. All of this is possible already and we only need the will to make it so. Devolution writ large. Can I persuade myself to not have a car? Well, I could be persuaded if matters changed relatively little and honestly I'd want the ability to go to the mountains a few times a year but I could get around going to visit family thanks to Skype and equivalents. Of course loss of liberty apparent or real is not acceptable politically, but moving the cost of travel would probably be far more acceptable—making this a choice and an economic choice. To do that, in turn, we need to embrace working from home and we need to find ways of making trust or proving truth or simply providing transparency such that this can occur.

DJS 20191205

Small edits made 20200712. Please note this is before the coronavirus outbreak, though not by much.

Further thoughts

1. A 'solution' I found offered in several places is to impose a small tax on email, e.g.  [10],[11] Is this echo-chamber stuff? [17]. I found a number of sources claiming this was easy and a similar number saying it cannot be done, yet I found no extant examples of anyone actually succeeding in doing such.The more I read, the more I decided that this was about as unlikely as getting the big internet businesses to pay taxes in the nations where their business occurs.

A subsidiary thought for others to write to me about: if one can, for example, buy electronics from remote places such as China, at what point could such gadgets have possibly been approved (certified) for sale in the UK or the EU? How could such a position be achieved? Suppose a gadget is unsafe, not by design but by omission; how does anyone have recourse back up the supply chain? Which connects quite nicely to the next point, which 'should' supply a suitable methodology at least for tracking who did what and when. It doesn't resolve where the metaphorical buck of blame or fault stops.

Without recourse to any external source, can you distinguish between these three terms?



bitcoin                                          ³

2. A different patch of reading gave me yet another explanation of what blockchain is, [19, much of which is worth a read; I recommend the first 15 pages or so, which you might interpret as ten minutes of your time].   Part of the explanation of the future uses of blockchain is that it offers the opportunity to share data in ways that provide reliable transparency of transactions. Now rethink the term 'transaction' from something with meaning to bankers and accountants and turn it into something more akin to 'who did what'. So think of shared documents, shared databases, anything with multiple users each of whom is an active supplier of content. This transparency, I am told, serves to engender trust where previously it has been missing. That strikes me as a possible route to a wholly different way our society could function, with many more of us working remotely from our colleagues. Do not read 'transparency' as equal to 'blame'. Issues yet to be resolved have parallels with voting systems (yes, blockchain ought to be usable for voting, but read on). 

The issue here is much as happens now with postal votes and is to do with how secure, in some sense, the end-user is. Suppose we postulate a family unit where one family member is the boss in such a way that the postal votes for all the family members are, in effect, cast by one person. [20, perhaps] .This defeats the principles of (i) secret ballot and (ii) undue influence, but strikes me as all too possible under certain cultural conditions. No arrest is likely (it is that level of offence) since the environment in which either principle is broken is probably rich which sufficient fear of reprisal that no complaint will be forthcoming.

In the same way, one can have a terminal (let's say using blockchain for some purpose) and we have the potential for the same issue, not knowing if there is abuse of power at the end. Such as who is doing the work, operating the terminal. This is, in essence, why coursework has largely disappeared from school. To an extent, a business doesn't much care quite who is doing the work provided the work gets done to an acceptable standard. This remains an issue where there is some critical factor of ownership of what occurs at the terminal.    This issue is not yet resolved, though I have long thought that simply framing the question better makes dramatic progress towards an answer.

¹ The link to the OVO source fails, sending one only to OVO's website. Searching their site found https://www.ovoenergy.com/ovo-newsroom/press-releases/2019/november/think-before-you-thank-if-every-brit-sent-one-less-thank-you-email-a-day-we-would-save-16433-tonnes-of-carbon-a-year-the-same-as-81152-flights-to-madrid.html  down at the bottom is the detail you want.

² Eventually I found this. Amazing how little is still on the web from as recent as 2010—it makes one wonder whether we are indeed discarding babies with bathwater; far too much copied many times and very little of actual value actually available. McAfee study, "Carbon Footprint of Spam". https://www.demainlemail.com/wp-content/uploads/2009/04/carbonfootprint2009.pdf

³  I made this easy, since bitcoin is a subset of cryptocurrency which is a subset of blockchain. Putting the biggest idea first, as you'd expect me to.

blockchain  - a peer-to-peer computing system that maintains its records (such as those of a cryptocurrency) across several (often many) computers.

cryptocurrency - digital currency using strong cryptography to make secure financial transactions, which includes verification of transfers and creation of additional units.

bitcoin   - A commonly recognised cryptocurrency, worth, at the time of writing, some £5600 each

[1]  https://www.cwjobs.co.uk/insights/environmental-impact-of-emails/

[2] https://www.google.co.uk/search?newwindow=1&source=hp&ei=JNHfXYrYCZL1kwWn74XABA&q=carbon+footprint+of+email+calculation&oq=carbon+footprint+of+email+calculation&gs_l=psy-ab.3..33i22i29i30l10.2621.14219..15065...0.0..0.107.2335.36j1......0....1..gws-wiz.......0i131j0j0i324j0i22i30.iC1B-rewOco&ved=0ahUKEwiK-vfnho3mAhWS-qQKHad3AUgQ4dUDCAs&uact=5

[3] https://www.bcg.com/en-gb/publications/2018/economic-case-combating-climate-change.aspx

[4] https://climatecare.org/infographic-the-carbon-footprint-of-the-internet/

[5] https://www.theguardian.com/technology/shortcuts/2019/nov/26/pointless-emails-theyre-not-just-irritating-they-have-a-massive-carbon-footprint.  The link within the piece to Gartner's report fails. Searching their site failed to find any relevant content too.

[6] https://www.theguardian.com/environment/green-living-blog/2010/jul/01/carbon-footprint-banana

[7] https://www.theguardian.com/environment/2010/aug/12/carbon-footprint-internet

[8] https://carbonliteracy.com/the-carbon-cost-of-an-email/

[9] https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email   Oct 2010

[10] https://www.cornellrooseveltinstitute.org/env/is-email-bad-for-the-environment

[11]  https://www.demainlemail.com/wp-content/uploads/2009/04/carbonfootprint2009.pdf  McAfee study, "Carbon Footprint of Spam".

[12] The Global Economic Impact of Spam. February 2005. Report #409.  http://www.ferris.com/2005/02/24/the-global-economic-impact-of-spam-2005/   failed for me. Try here https://www.semanticscholar.org/paper/The-Economics-of-Spam-Rao-Reiley/94a91a68254f2cc52c4f331c7f029b3f366b914e

[13] http://www.radicati.com/wp/wp-content/uploads/2015/02/Email-Statistics-Report-2015-2019-Executive-Summary.pdf  Email data

[14] https://epdf.pub/queue/how-bad-are-bananas-the-carbon-footprint-of-everything.html may let you read MB-L yourself.

[15] https://googleblog.blogspot.com/2009/01/powering-google-search.html

[16] https://www.eecabusiness.govt.nz/tools/wood-energy-calculators/co2-emission-calculator/

[17] https://computer.howstuffworks.com/e-mail-messaging/e-mail-tax.htm irritating site.

[18] https://en.wikipedia.org/wiki/Internet_tax  and yes, I continue to subscribe by way of support. This is an unusually poor piece.

[19] https://static.cbsileads.com/direct/whitepapers/TR_SF-Blockchain_r1__1_.pdf

[20] https://publications.parliament.uk/pa/jt200203/jtselect/jtrights/186/18617.htm   I spotted re1evant, an unlikely typo, also at borne for 'at home'.. If you want to read more on this, the issues are (i) secrecy of the ballot and (ii) undue influence.  Well worth reading the numbered points in the Annex.

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