UK law currently requires us to reach net zero greenhouse gas emissions by 2050. ‘Net zero’ means that on balance we are not putting any more emissions into the atmosphere.

We know that net zero is our destination—but, actually, it is not so much when we get there that matters, but more the path we take. This is why the CEE Bill does not contain a specific net zero target date.


Instead, the CEE Bill draws on the idea of the “carbon budget”. This divvies up the emissions that each country can produce if we are to stay within safe global temperatures. 

The world’s leading UN climate scientists told us in 2018 that we must not put more than another 420 billion tonnes of carbon dioxide into the atmosphere if we want a reasonable (66%) chance of keeping the global average temperature rise within 1.5ºC. 

How long we can keep burning fossil fuels then depends on how quickly we get on with cutting emissions. Let’s look at three possible paths we could have followed from 2018.

Illustration - fixed % pathway to net zero from 2018


1. Faster at first

The IPCC strongly advised the world in 2018 to make ‘ambitious near-term cuts’ in emissions.

As you can see in the graph on the left, this would stop us eating through our 420 billion tonne budget too quickly, allowing us to continue burning fossil fuels until 2050. 

This would have required 8% annual cuts immediately from 2019.


Illustration - equal cuts pathway to net zero from 2018


2. Slower start

Cutting less steeply at first means the budget gets used up faster in the early years. So to stay within our 420 billion tonne budget, we must then reach net zero sooner!

Illustration - actual to 2020, with delay until end 2023


3. More delay

Here’s what actually happened up to 2020 where you see a dip due to the pandemic. But emissions in 2021 are now already back at 2019 levels.

If we fail to start seriously cutting until 2024 then, to stay within our budget, we will have to really hit the brakes - even more sharply than during lockdown…


4. Tunnel vision on 2050

Setting distant targets without a focus on reducing emissions right now is a recipe for disaster.

Here’s what could happen if emissions keep inching up until 2024. Look how easy it is to really overshoot our budget if we don’t get to grips with emissions right now! In this scenario, we use double the budget—840 billion tonnes—despite still reaching net zero in 2050.


Every extra day of delay means even steeper cuts will be needed to avoid blowing our carbon budget. Focusing exclusively on net zero by 2050 makes very little sense. 

That’s why the CEE Bill would require performance to be monitored annually against legally binding targets to make sure we stay on track.