This is a commentary on a report on the UK's CO2 budget titled Zero carbon sooner by Prof Tim Jackson of the Centre for the Understanding of Sustainable Proposperity (CUSP) at the University of Surrey.

It was published in 2021 following the publication of the IPCC's AR6 WG1 report.

• At the current trend (line (a) in the chart), or via the net zero 2050 steady reduction (line (b)), the UK's per capita "fair share" of the residual global CO2 budget will be used up in 3 years, i.e. in 2025.
• By reducing emissions rapidly, the UK's fair share of the CO2 budget can be made to last to 2027, if the pathway is a steady (straight line i.e. linear) decline - line (c).
• The UK's fair share of the CO2 budget can be made to last beyond 2027, but only if emission cuts are even steeper, e.g. a 27% year-on-year decline - as in line (d).
• The UK Government's Net Zero 2050 strategy would lead to the UK emitting several times its fair share of the residual CO2 budget.
• To merely specify the net zero date of a strategy is insufficient, the pathway of emission cuts is crucially important.

• the aim is to keep global warming below 1.5°C with 67% likelihood
• the IPCC gives 400 billion tonnes CO2 as the remaining global carbon budget for this aim [1]
• this global carbon budget should be divided between countries on a per capita basis, with a reduction for the UK of 14% to allow for its current emissions being well above the average

• all emissions due to UK residents should be included, including via purchase of imports.

• There is a wide disparity between the UK Government's Net Zero 2050 approach and what it is committed to via the Paris and other agreements.
• Many campaigning groups are out of step with the climate science - exceptions are the youth climate activists and Extinction Rebellion (with its net zero 2025 demand).
• Society in general is unaware of the urgency of the climate emergency, and of the size and speed of changes needed.

• The Tyndall Climate centre has produced reports for each UK local authority, with broadly similar conclusions [2]
• The website https://carbonbudgetcalculator.com gives pathways for various starting points and countries (but does not include imported goods).
• Charts similar to the one shown from the CUSP report have been published at frequent intervals for many years. This chart [3] was published in 2018 in the Global Carbon Budget 2018 [4].

• Prof Tim Jackson's introductory text: https://timjackson.org.uk/zero-carbon-sooner-update/
• PDF: https://cusp.ac.uk/wp-content/uploads/WP-29-Zero-Carbon-Sooner-update.pdf.

References