Are Current UK Greenhouse Gas Emission Limits Fit For Purpose?

by Carl Edward Rasmussen, 2023-03-30

Greenhouse gas emission targets for the far future, such as 2030 or 2050 cannot stand on their own. If they do, we risk arriving at those dates without having achieved the targets, and being out of time to correct our actions. Instead, future targets must be supplemented by frequent binding checkpoints along the way. The UK has been brilliant, and almost unique in the world, in legislating yearly emission limits starting in 2008.

The purpose of the yearly UK government targets for greenhouse gas emissions is to ensure that the UK is on track to reduce our impact on climate change. The 2050 goal is to reach Net Zero. One worry is that action now gets substituted with promises for the future. Such a substitution is undesirable because 1) it may turn out impossible to achieve at the time (but will then be too late to do anything about it) and 2) it commits people in the future to act, rather that taking action ourselves.

So, the emission limits are brilliant in principle, but are the actual values appropriate? Are the current limits set by the government fit for purpose? Do they make it plausible that we're on track to the 2050 Net Zero goal? Below I've plotted these limits together with the actual emissions for 2018-2022 for context, expressed in tons of CO2 equivalent per person per year.

UK Greenhouse Gas Emission Limits

In the plot above, I've taken the 5 year budgets from the Climate Change Act, normalised them by dividing by the UK population size, and plotted the individual yearly limit such that the year to year reduction is 6% (and that the 5 year total coincides with the legislated limit). For the third budget 2018-2022 I've plotted the actual emissions. For the 5th budget 2028-2032, I'm assuming that the NDC 2030 committment isn't supposed to be a one off isolated limit so I've extended to 2031 and 2032 and split the remainder of the budget 2 ways for 2028 and 2029. I've superimposed a hypothetical insufficient curve starting from the actual average 2018-2022, with a constant yearly rate of reduction of 6%. If we followed that line, we would reach 1 ton per person per year in 2050, and not Net Zero.

Are the limits set on target? The answer is no. Every one of the 15 targets set are above a curve of constant relative reduction of 6% per year, a curve which is insufficient to get close to Net Zero by 2050. The 4th budget 2023-2027 exceeds the insufficient 6% curve by more than 20%. The limits for 2028-2029 are so large, that they're practically vacuous. The CCC claim in their 6th Carbon Budget Report (chapter 10, section 3) that "It is our assessment that the Fourth [2023-2027] Carbon Budget is on track...". I think those limits are not on track, they're inadequate. The first two years of the 5th budget are nearly 100% in excess of the insufficient 6% curve. The CCC's opinion of the 5th budget is that it is not adequate. However, they say "It is for the Government to decide whether the currently legislated budgets are amended to bring them in line with the revised 2050 target or the 2030 NDC, but the Committee does not consider it to be necessary". I think it is highly necessary to amend those limits. The whole point of having limits is to keep the process on track, so how can inadequate limits be deemed adequate? Finally the 6th budgetlimits are also inadequate in meeting the insufficient 6% curve (but I acknowledge the extra complication that this includes international aviation and shipping, which for the purposes of all the other limits have been excluded).

One may perhaps criticise the use of even relative reduction of 6% for comparison. But I think even relative reduction is in fact quite a conservative strategy (at least up until very close to reaching Net Zero), as some reductions are much easier to achieve that others. Therefore, the reductions will initially focus on the "low hanging fruit", and will become progressively harder over time.

Sadly, while the principle is brilliant, the limits set are mostly not fit for purpose. The current limits are not on target even for an insufficient 6% reduction per year. These targets must be updated and strengthened, to make sure we are on track to our goals, and not merely promising that someone in the future will sort it out.

Last modified: Thu Mar 30 13:59:23 BST 2023