ITU-T Recommendations: Green ICT Standards and Supplements

 https://www.itu.int/net/ITU-T/lists/standards.aspx?Group=5&&&&Domain=28 

Digitalization & Energy

https://www.iea.org/publications/freepublications/publication/DigitalizationandEnergy3.pdf

How to stop data centres from gobbling up the world’s electricity

https://www.nature.com/articles/d41586-018-06610-y

The Surprisingly Large Energy Footprint of the Digital Economy [UPDATE]

http://science.time.com/2013/08/14/power-drain-the-digital-cloud-is-using-more-energy-than-you-think/

What's the carbon footprint of ... email?

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

What's the carbon footprint of … the internet?

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