What is Green Tech and Green Software Development?
Microsoft Refactor 2021 · Europe
by Asim Hussain · 19 May 2021
I was interviewed by James Wollard for a Microsoft Reactor session, run as a free-flowing Q&A, about what green tech and green software development actually are — starting from the climate basics, working through all the carbon jargon companies throw around, and landing on why I think software is one of the best levers we have to pull right now.
AI-generated summary of my talk
Jump into the talk
- 4:05 Defining climate change: mitigation vs adaptation
- 7:07 Carbon-neutral, net-zero, carbon-negative
- 11:10 Avoidance vs removal offsets, and Microsoft's shift
- 18:13 Where software fits in
- 20:14 Principles of Green Software Engineering — not a checklist
- 24:15 The Green Software Foundation
- 26:16 The numbers: 15% utilisation, 30 million developers
- 33:20 Policy as the tipping point, and climate tech beyond software
What we mean by climate change
The climate’s always changing — it’s been changing for millions of years and always will. The problem right now is that it’s changing too fast for animals, plants and humanity to adapt. So in the climate community there are two halves of the conversation: mitigation and adaptation. Mitigation is pumping the brakes a little, slowing things down so we can keep up. Adaptation is how we cope with what’s already coming — and, unfortunately, that conversation is almost entirely about how humans adapt. Nobody’s drawing up plans to help the dolphins.
Underneath all of it the root cause is simple. On my podcast I ask every founder what problem they’re solving, and most of us — me included — give long, complicated answers. The founder of a US startup called Nori gave the best one I’ve heard: there’s just too much carbon in our atmosphere, and we need less of it. We’ve already caused roughly one degree of warming over pre-industrial times, we’re on track for something like three-and-a-half to four degrees by the end of the century, and in the 2016 Paris Agreement we all agreed to try to hold it to 1.5.
Carbon-neutral, net-zero, carbon-negative — and the offset trick
People throw these terms around and they are not the same thing. Carbon emissions get accounted for under the GHG Protocol — think of it like a monetary accounting standard, but for carbon — split into scope 1 (stuff you directly burn, like a diesel engine), scope 2 (the electricity you buy) and scope 3 (your whole value chain). Scope 3 is the big one: for an Xbox it’s every emission from every component, plus all the electricity someone burns playing it at home.
Carbon-neutral has a famously loose definition — you offset scope 1, scope 2 and however much of scope 3 you feel like, with very little said about what kind of offset you use. That last bit matters enormously, because there’s a world of difference between an avoidance offset and a removal offset. Avoidance is “I’ve got this forest, I was going to chop it down, but pay me and I won’t” — or going round buying up old refrigerant so it doesn’t leak. It stops new carbon, but it doesn’t take anything back out. Removal does: you grab carbon out of the atmosphere and put it back in the ground.
Net-zero raised the bar — for every molecule you emit, you pull one back. The Science Based Targets initiative is even stricter: you can’t just buy your way clean, you have to cut your emissions as hard as you possibly can and only then buy removals for what’s left. Carbon-negative goes one further — remove more than you emit. Microsoft committed to carbon-negative by 2030, and the part buried under that headline is the hard part: cut our own emissions by half first, not just offset today’s number. We also went all-in on removals — buying the entire market for removal offsets in a year, deliberately, to force that market to grow.
Why software, and why it’s a whole discipline
When James asked where software actually sits, here’s the honest answer: everyone has to do their share. Every country agreed to halve emissions by 2030, and that has to land on every sector — the farmer, the coffee producer, the hardware engineer, the software engineer. My job is to work out what software engineers can do, and it’s oddly under-explored. Loads of research has gone into more efficient hardware and more efficient data centres; almost none into software. When I started there were maybe three books on software sustainability in existence, all about web development.
So we started building training — the Principles of Green Software Engineering. My first instinct was to write the 12-point checklist: tick the boxes and your software’s green. After hundreds of conversations I realised that was hopeless. The advice is deeply contextual — web is different from machine learning, and one corner of ML is different from another — so what we’re really doing is creating an entire new field of computing. The very first principle is carbon, partly because I kept discovering that my definition of “green” and the next person’s were completely different, and you can’t optimise together until you’re speaking the same language. Funnily enough, it forced me to learn how electricity actually works — something my entire job depends on and I knew nothing about.
This is also why we were about to launch the Green Software Foundation — a vendor-neutral, non-profit body run under the Linux Foundation, a vehicle for companies to collaborate on standards and best practice rather than each going it alone.
The numbers, and where I think this is heading
Two stats I always give. First, from the Uptime Institute: average server utilisation across the world is around 15%. Most servers are sitting idle. That’s a huge upside — getting from 15% to 30%, or 30% to 60%, is genuinely achievable, and unlike hardware tweaks that buy you single-digit percentages, software changes can be 2x, 3x, 4x. Second, ICT is projected to grow to somewhere around 3–8% of global emissions by 2040. That might not sound like much, but the entire transport sector is about 15% — so it’s significant. And the real point is leverage: to move transport you have to change the behaviour of billions of people; to move software you need to reach 30 million developers, and realistically only about a million of them, to make a real dent.
The biggest lever of all, though, is policy. A standard is something a company voluntarily adopts; a policy is a standard made mandatory by government. I’ll put money on the first real green-software policy coming out of France — there are too many hints, from a draft law that could be read as banning infinite scroll, to Macron musing about whether every app should have to report its carbon intensity. The day a government mandates that, every company will suddenly want to hire a green software engineer, and that’s the tipping point for the whole field.
And it’s worth zooming out, because software is one slice of a much bigger climate-tech picture: electric vehicle fleets that are smaller, shared and self-driving rather than one-for-one swaps; meat replacements (I’m an amateur mycologist — a lot of this is fungus); direct air capture, where one of the best places to bury the carbon turns out to be the very holes we pumped the oil from; and concrete, which on its own is about 8% of global emissions, now being reinvented to actually absorb carbon as it cures. We’ve even passed the point where human-made mass on the planet outweighs all living matter — which tells you something about the scale of what we’ve built, and what we now have to fix.