Editorial - Special issue: green photonics

The power consumption of communication systems and networks has continued to increase over the recent past driven mainly by growth in Internet traffic. This is currently growing at 30-40% annually, leading to traffic growth predictions of 30 ?? in 10 years and 1000 ?? in 20 years (for example figures predicted by GreenTouch). ICT systems and networks currently have a carbon footprint that is comparable to the global aviation industry (2% of the world??s carbon footprint); however, unlike aviation, they continue to grow at an incredible rate. The situation is therefore not sustainable and there is an urgent need for energy efficiency and a reduction in the network´s carbon footprint. Although in some cases the use of ICT can be beneficial to the environment (for example by reducing journeys and introducing more efficient business processes), countries are becoming increasingly aware of the very large growth in energy consumption of telecommunications companies.