The purest, lightest, least polluting form of digital communication is text. Let’s assume for a moment that a picture does indeed “paint a thousand words”. 1,000 words weighs about 6 KB and typically will take up about two A4 pages. A picture—or set of pictures—taking up the same area of layout will weigh many times more than that. So, a picture has a much greater carbon footprint than an equivalent piece of text.

The text format used impacts the weight of text. Done properly, HTML is a light, environmentally friendly way to publish text. 1,000 words of text optimally formatted in HTML should weigh no more than 7 KB. However, if you simply save a thousand words as HTML using Microsoft Word, for example, that file will likely be more than 50 KB because Word introduces lots of unnecessary code. 1,000 words as a Word document will be about 16 KB. Saving 1,000 words as a PDF will be more than 60 KB. So, for the exact same piece of text, PDF can be nine times more polluting than optimized HTML. For this and many other reasons, optimized HTML should be the choice of the environmentally conscious communicator and designer.

When sending emails, always try and send using the text format. In a series of tests I did with Microsoft Outlook, I found that an HTML email weighed on average three times as much as a text email. Always think: what’s the lightest communication option?

Images taking up the area of two A4 pages will range in weight from about 180 KB to almost 1 MB, depending on how they are optimized. So, images can be up to 200 times more polluting than text. Choose images carefully. A huge number of images on webpages are pointless—cliché, ego and vanity. They don’t communicate anything useful. They merely strut and show off. These deeply embedded wasteful habits are part of the wider culture that has caused the climate crisis. We publish in order to show off rather than to communicate.

It takes about four minutes to read 1,000 words. Four minutes of audio can weigh anything from 3.6 MB to 66 MB, depending on the format. So, audio can be up to 11,000 times more polluting than text. Always avoid WAVs when dealing with audio (unless you’re doing music production). Audio can indeed be very powerful but we need to use it carefully and frugally.

Four minutes of highly compressed video can weigh about 31 MB. Saving it as 8K video can weigh an astonishing 2.4 GB. So, video is potentially an astonishing 400,000 times more polluting than text. Video must be used very sparingly. Every second that can be cut should be cut. One second of standard YouTube video weighs as much as 42,000 words of optimized HTML.

Remember: just because it’s the heaviest option does not mean that it’s the best and most effective way to communicate. Text is often far superior to images, audio or video. Choose your way to communicate intelligently and environmentally consciously. Do not be driven by fashion, misplaced cool or organizational vanity and ego. So much about modern human life is heavy on the earth. From our monstrous SUVs to our superficial, overblown communication, we extract vastly more earth resources than are needed simply because we can.