Some changes to Sustainability by Numbers in the new year
It has been a busy year for me. I’ve still published a lot on this Substack, but not as much as I’d want. I do this in my spare time, and it’s truly an enjoyable outlet to think things through, dig into questions, and see if I can get my ideas across.
I’m extremely grateful to everyone who follows along, gets in touch, and engages thoughtfully with each of my posts (even if you disagree). There are now more than 67,000 of you.
As we move into another year, I’ve decided I’m going to broaden the focus of my Substack a bit. So far, it has mostly focused on environmental problems (and has been pretty broad within that category: everything from deforestation and fertilisers, to clean energy and artificial intelligence). This is something I’ve always been passionate about (and still am), but I also spend a lot of time trying to understand other pressing problems through the lens of data.
I already do this at Our World in Data (my main job), where I write about everything from foreign aid and demographic change to technology, tuberculosis, global health media bias.
I’ve often wanted to cover these types of topics on this Substack, but feel limited to sticking to strictly environmental ones. That is what I think a lot of my audience signed up for. While it’s also implied in the name — “Sustainability by Numbers” — as anyone who has read my recent article will know, all of the issues that matter for human development today also fall within my definition of “sustainability”. But my guess is that people automatically think about environmental problems when it’s mentioned.
In 2026, I’ve decided to take the leap and branch out a bit. I’ll still write a lot about energy, climate and other environmental stuff. But I’ll also cover other issues. That includes everything from demographics and technological change to global health and development. The approach of my work won’t change: it will be data-led and focused on what the numbers can tell us about a particular problem or its solutions.
I know that I might initially lose quite a few subscribers. That’s fine. I hope that those who follow me for discussion on environmental topics are equally as excited about other global developments, and will stick around, but I understand if that’s not for you. I don’t charge anything for my Substack (payments are switched off), and I do it for fun in my free time. I want to keep it fun and interesting, which means not limiting what I can write about.
To reflect this change, I’m going to rename the newsletter “By the Numbers” [note that you don’t need to take any action or subscribe elsewhere; this will all happen automatically]. Similar vibes, but it avoids people assuming that sustainability is only about environmental problems.
If you stick around, thank you.1 I’m excited to see what questions we’ll explore in 2026.
Wishing you all the best for the year ahead.
p.s. if you’re looking for some festive reading, my new book — Clearing the Air — is on offer at £1.99 on Kindle for the next 24 hours. Hope you enjoy!
If you don’t, thanks for following along this far. Note that you’ll have to do this on the app or on your Substack.com dashboard. I can’t do this for you via an email reply.
Thank you for your work! I suspect you won't lose many subscribers, if any, people want to read about the topics you find interesting/important!
Gracias Hannah! Agree w/your broad definition + both applaud and thank you for offering your thoughtful insights freely! Wishing you a very happy holiday and all the best for 2026!