Earth Hour: What is the carbon footprint of an e-mail?

  • TECH
  • Saturday, 28 Mar 2015

ENVIRONMENTALLY FRIENDLY: People around the world are getting ready to mark Earth Hour by turning out the lights on Saturday.

PARIS: Sending a text message or e-mail, eating an apple or watching TV – each of these activities has a different carbon footprint. 

People around the world are getting ready to mark Earth Hour by turning out the lights on March 28, but a long list of seemingly harmless everyday actions also contribute to emissions of carbon dioxide (CO2) and other planet-harming greenhouse gases. 

Total global emissions in 2010 were estimated at 49 gigatonnes (Gt or billion tonnes) of CO2 equivalent (CO2e). 

E-mail and Internet 

Even a short e-mail is estimated to have a footprint of four grammes (0.14 ounces) of CO2e (gCO2e) – including greenhouse gases produced in running the computer, server and routers and a part of their manufacture. 

An e-mail with a large attachment emits about 50 gCO2e, and a spam message, not even opened by the recipient, is responsible for 0.3 gCO2e. 

The annual global footprint of spam is equivalent to 3.1 million passenger cars on the road in a year, using two billion gallons (7.6 billion litres) of gasoline. 

A web search on an energy-efficient laptop leaves a footprint of 0.2 gCO2e, and on an old desktop computer some 4.5 gCO2e. 

A cellphone text message comes at a cost of about 0.014 gCO2e. 


A plastic carrier bag leaves a footprint of 10 gCO2e, and a paper bag 40 gCO2e. 


A pint (473 millilitres) of water from the tap generates 0.14 gCO2e compared to 160 gCO2e for a 500 ml store-bought bottle. 

A large cappuccino comes at 235 gCO2e, compared to 21 gCO2e for a cup of black coffee or tea for which just enough water was boiled. 


An hour of TV watching on a 15in (38cm) LCD screen yields 34 gCO2e, compared to 88 gCO2e on a 32in LCD screen, and 220 gCO2e on a 24in plasma screen. 

A mile of cycling powered by a meal of bananas would be responsible for 65 gCO2e, compared to 260 gCO2e for a mile powered by cheeseburgers. – AFP 

(Sources: How Bad Are Bananas by Mike Berners-Lee, Fifth Assessment Report of the UN's Intergovernmental Panel on Climate Change, McAfee study Carbon Footprint of Spam.)

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