The first principle is to not create. Not doing anything with digital is the kindest thing you can do for the environment. The decisions that you make not to create that extra piece of code, that extra piece of content, these are the most important decisions you can make. If you must create then reuse and recycle code, content and designs. The more you can build from stuff that has already been created, the better for the environment.

The second principle is to make stuff that is reusable. Build stuff in a modular way so that others can easily use parts of it. How can you make stuff so that others who need it can easily find it? In practical terms this means that you have to carefully think about the metadata that will describe and help organize what you create. Without good metadata, digital stuff is not findable. When people find your stuff will they be able to easily understand what it does and how to reuse it? You need to carefully describe how the stuff was made, what rules, languages, procedures, processes it follows.

The third principle is to minimize waste during reuse and creation. The more waste you’re creating the more you are helping accelerate global warming. The less weight your design has, the less waste it’s creating. The less processing your design requires, the less waste it’s creating.

According to Mike Berners Lee, sending an SMS message creates 285 times less waste than sending the same message by email. I did some calculations and found that sending the same message by audio would create roughly 28,000 times more pollution. Sending the same message by standard video would create 214,000 times more pollution. These are massive, almost unbelievable orders of magnitude of difference.

At every part of your day, you can make decisions that will be gentler on the environment. Every time you save 15 minutes on a video conference, you do something good for the environment. Every time you choose audio over video, you do something good. Every time you choose text over audio, you do something good.

We were always a wasteful species but in the last 50 years our wastefulness has utterly, absolutely exploded. We are literally wasting the earth to death. The nature of digital encourages a waste mindset. Digital makes it so easy to waste that we don’t even think we’re wasting. By focusing on digital waste we begin to change our mindset. We must change our mindset because it is our culture of waste—of convenience, of disposability, of things being “old” when they are three years old, of “free” digital products and services—that is a huge accelerator of global warming.

What you save when you send an SMS instead of doing a video conference call may seem inconsequential in the larger scale of global pollution, but it is the cost closest to zero that is the most dangerous cost of all. And the most important thing is to realize that there is nothing remotely free about digital, that it is the digital mindset that is a great accelerator of global warming. Free costs the Earth.