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

The urgency of the climate emergency can be quantified by the carbon budget:
  • how much more CO2 can be dumped into the atmosphere
  • how long this budget will last at current emission rates.

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

This timescale is very far from what UK citizens have been led to believe, so the calculations are set out here in detail so readers can check for themselves.

Burning of fossil fuels needs to be phased out urgently.

How urgent is an "emergency"? After the 2019 street protests, many national and local administrations declared a climate emergency but have since failed to implement the "rapid and far reaching transitions" recommended by the Intergovernmental Panel on Climate Change (IPCC) 2018 report [1], which sparked the protests. Some governments, including the UK's, have even encouraged fossil fuel use by measures such as further road building.

The residual carbon budget
The urgency of the climate emergency can be quantified by the carbon budget how much more CO2 can be dumped into the atmosphere and by how long this budget will last at current emission rates. It turns out that the UK's fair share of the global carbon budget will be used up in just 3 years. The maths are simple, but this timescale of 3 years is so far from what is being discussed that it is worth explaining the calculations in detail, as follows, so that readers can check for themselves.

The calculations
1. The residual global carbon budget is 400 billion tonnes CO2. This is the amount from January 2020 given on page 38 of the 2021 IPCC report [2] as the global carbon budget to limit global warming to less than 1.5C with 67% confidence.
2. Dividing the 400 billion tonnes CO2 between the 8 billion world population gives 50 tonnes CO2 per person on the planet as a personal lifetime carbon budget.
3. Since the UKs emissions are around 10 tonnes CO2 per person per year (document 23), the UKs fair share will last 5 years from January 2020, that is until December 2024 just 3 years away.

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.



The main points on this page are also online:


References

[1]IPCC (Oct 2018) SR15 Summary for policymakers https://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf
[2]IPCC (Aug 2021) AR6 Climate Change 2021: The Physical Science Basis https://www.ipcc.ch/report/ar6/wg1/ (The IPCC is the United Nations body for assessing the science related to climate change.)
[3] Tyndall Centre The Tyndall carbon budget tool (2019) https://carbonbudget.manchester.ac.uk/reports/

First published: 28 Sep 2021
Last updated: 3 Nov 2021