The UK's share of the Paris-compliant global carbon budget will run out in 3 years

The IPCC AR6 Report of 2021 indicates that the remaining carbon budget to remain within 1.5° of global warming is 400 billion tonnes CO2.

The UK's fair share of this will run out in 3 years (at the end of 2024).

Most UK citizens are unaware of the urgency of the situation.

Burning of fossil fuels needs to be phased out urgently.

The main points on this page have also been published:

The IPCC report of August 2021 (the AR6 WG1 report) [1] gave 400 billion tonnes (400Gt) as the maximum amount of CO2 that can be emittted globally without a major risk of devastating consequences. To be precise, this is 400 billion tonnes from 1 Jan 2020 to give 67% confidence of keeping global warming to 1.5°C. This is an update on the IPCC SR15 report of October 2018 [2] which gave 420 billion tonnes from 1 Jan 2018 for the same figure.

With the world population approaching 8 billion, this 400 billion tonnes is 50 tonnes CO2 per person when shared equally. This is a total lifetime limit.

The UK CO2 emissions are around 10 tonnes per person per year [3], and so its fair share of the carbon budget will run out in 5 years, i.e. at the end of 2024, i.e. in 3 years.

Most people are either unaware or in denial about the severity and urgency of the climate emergency.

Why the 3-year timescale should be common knowledge

Why the 3-year timescale is not common knowledge

Action needed

To stay within this budget, UK citizens now need to make radical reductions in emissions (as explained by the IPCC). Some simple maths tells us that reducing the UK average by 20% per year as an exponential decline will achieve this - see chart. A reduction of 20% year-on-year is about the same as halving every 3 years.


[1]IPCC (Aug 2021) AR6 Climate Change 2021: The Physical Science Basis (The IPCC is the United Nations body for assessing the science related to climate change.)
[2]IPCC (Oct 2018) SR15 Summary for policymakers
[3] (Figure 21, p46)

First published: 28 Sep 2021
Last updated: 15 Oct 2021