The Internet is a complex network of routers, switches, servers, firewalls, various types of endpoints, and wireless access points each of which require power. The amount of power required is obviously affected by the amount of data being transferred and processing power being used to render the graphics we all enjoy.
Just as citizens of various countries are also citizens of the world, users of the Internet are Netizens and we all have a responsibility. As individuals our collective usage of the Internet is growing and so is our power consumption and all the pollution, carbon emissions, and greenhouse gasses that go along with it.
On average, advertisements, unnecessary java scripts and tracking scripts make up approximately 40-60% of website traffic.
A nice side benefit to implementing network based ad blocking for security is the power savings gained by reduced data transmissions and reduced processor usage for rendering ads.