What's in a number? The small print behind the UK's NDC

By Richard Black, Director @_richardblack

Published:09 November 2020

In the UK’s climate change community there’s been no more talked-about number in recent months than that which will form the centrepiece of the UK’s NDC, or Nationally Determined Contribution.

The NDC will be the first international test of Boris Johnson's claim to be a climate leader. Image: Number10
The NDC will be the first international test of Boris Johnson's claim to be a climate leader. Image: Number10

This is the pledge that the UK will put forward, as will many other countries, ahead of COP26, the UN climate summit that should be taking place in Glasgow this fortnight but which Covid-19 has shunted into the tail-end of next year.

In the Paris Agreement of 2015, governments requested each other to put forward new NDCs this year containing, among other things, enhanced national targets for cutting emissions to 2030.

On 9th December the Climate Change Committee (CCC), the Government’s statutory advisor, will formally declare what it thinks the number should be. Government may or may not take the CCC’s advice, though it generally does, and could publish its NDC on 12th December, the fifth anniversary of the Paris Agreement.

Whenever the NDC comes, analysts and observers will naturally be taking a view about how ambitious it is; and there’s some crucial small print to go through in order to make sense of it.

Re-calculating history

The UK already has a national target for emission reductions by 2030. It is the figure given in the Fifth Carbon Budget (5CB) covering the period 2028-2032, which was agreed by Parliament and is legally binding on Government.

The UK’s carbon budgets are given in tonnes of emissions, not as a percentage fall from baseline. Over the five years of the 5CB period, total emissions of all greenhouse gases from all sources except the UK’s share of international aviation and shipping are limited to 1,725 million tonnes of carbon dioxide equivalent (MtCO2e). Per year, that works out at 345 MtCO2e.

That equates to a fall, from the 1990 baseline that nearly everybody uses for such things, of 57%.

Or rather… it did.

Emissions from peatlands have turned up to be higher than previously thought, changing the calculations. Image: Tero Laakso, CCL
Emissions from peatlands have turned up to be higher than previously thought, changing the calculations. Image: Tero Laakso, CCL

A few things have happened which change that percentage.

One is that it now looks certain that the UK will come out of the EU Emissions Trading Scheme (ETS) at the end of the year. The ETS covers emissions from big sources like power stations and factories and allows them to trade ‘pollution permits’ with each other.

Recalculating the baseline... changes in science mean the UK's emissions were higher in 1990 than previously thought, hence the percentage emission reduction higher
Recalculating the baseline... changes in science mean the UK's emissions were higher in 1990 than previously thought, hence the percentage emission reduction higher

The existing method for totting up emissions inside the ETS is based on the allocation of ‘pollution permits’ to UK facilities, not on the actual emissions of those facilities.

On the basis of actual emissions, meeting the 5CB target, in the CCC’s words, ‘requires a 61% reduction from 1990 to 2030’ rather than a 57% reduction. That doesn’t represent any additional ambition from Government – it just reflects the real-world way of counting emissions.

Another issue is that the UK’s emissions in 1990 are now known to have been higher than previously thought. And there are two separate reasons for that.

One is that in 1990, there were serious flaws in measuring emissions from peatlands – not just in the UK but worldwide.

The other is that methane is now known to be a more potent greenhouse gas than was believed in 1990 – 34 times more potent than CO2, rather than the previous estimate of 25 times.

Together, these two factors push the figure for UK emissions in 1990 up from 818 MtCO2e to 863 Mt – higher by 45 Mt, or about 5%. That in turn means that the emission cut needed to meet the existing 5CB target is not 61%, but about 64%.

So if the UK were to submit an NDC that simply turned existing national policy into UN climate convention form, the number on it would logically be around 64%.

The net zero context

The existing 2030 target was set in law in 2016, when the UK’s long-term target was an 80% emissions cut on 1990 levels by 2050.

Since last year, the long-term target has been net zero… so, what should emissions be in 2030 in order to get on track?

One approach to answering that question is simply to plot a straight line on a graph, starting at current levels of emissions and reaching net zero in 2050.

In fact the CCC did this in last year’s Progress Report to Parliament, plotting a line from the real 2018 level of emissions and reaching zero in 2050. This gave the level of emissions in 2030 as around 307MtCO2e.

However, this calculation was prior to the introduction of the new metrics for peatland and methane. Because the UK has reduced methane emissions, especially from landfill sites, these add less than they did in 1990 – an estimated 35MTCO2e, making the logical path to net zero pass through about 342 Mt in 2030.

This equates to a cut of about 60% from 1990 levels – or, if you add on the 4% for coming out of the ETS, again, 64%.

Straight to zero?

However… the most logical pathway to net zero isn’t necessarily a straight line. Many factors including the changing cost of technologies can make it logical to decarbonise faster or slower in specific periods. The CCC could therefore propose, or Government decide, to go faster or slower than the ‘straight line 64%’ over the next decade.

It’s very unlikely to propose going slower, because that would imply not meeting the already legislated 5CB.

But a recommendation to go faster over the next decade is feasible – even logical. Apart from the obvious rationale that the need to tackle climate change is getting more urgent and public support more evident, it could for example be justified on the basis that in the unique circumstances of a Covid recession it makes good sense to invest quickly and heavily in jobs-rich measures such as insulating homes, installing EV charging points and restoring peat bogs.

Equity, politics and flying

There are three other factors that government and the CCC may take into account.

The first is that currently, UK carbon budgets don’t include the UK’s share of emissions from international aviation and shipping (IAS).

Emissions from aviation are rising - but not yet captured in UK carbon budgets. Image: Raquel Baranow, CCL
Emissions from aviation are rising - but not yet captured in UK carbon budgets. Image: Raquel Baranow, CCL

The government could decide to publish an NDC including aviation and shipping emissions in the headline number.

But that would mean having a smaller headline number. IAS emissions have risen since 1990, and there’s little prospect of them falling far over the next decade, as technologies such as electric aviation and ammonia-powered shipping will take longer to become mainstream.

Adding international aviation and shipping (IAS) emissions would decrease the headline number, so it might miss the flight...
Adding international aviation and shipping (IAS) emissions would decrease the headline number, so it might miss the flight...

If you add the IAS emissions onto the figures given above for 1990 and projected for 2030, you get a reduction of 62% rather than 64%.

As part of the aim of publishing an ambitious NDC is to encourage other countries to follow suit, it might be deemed that a bigger number without IAS is preferable to a smaller one with IAS – although in this case, the NDC would still have to contain some wording about constraining emissions from these sources.

The second issue is equity – essentially, is the UK doing its fair share compared with other nations to keep global temperatures below 1.5ºC?

As a developed nation the UK is pledged under the UN climate convention to move faster than developing ones. But how much faster is not easy to pin down.

The CCC says its 2050 net zero target is equitable, though some campaigners and less developed countries argue it’s not – they would be urging the UK to go substantially above and beyond the ‘straight line’ 64% on the basis that it has a hefty legacy of historical carbon emissions to make up for, and the economic health to do so.

Others might argue that the UK must move faster for the third reason in this list – politics.

The Government wants to be seen as a climate change leader. But as my colleague Alison Doig wrote last week, there is a good deal of disquiet among frequent observers of the UN climate negotiations about the dearth of visible evidence.

Well – doesn’t leadership entail setting the most ambitious NDC possible? And since this is the first NDC that the UK will publish unilaterally having previously been covered by the EU's, don’t Brexit politics demand that it certainly should not look unambitious beside the EU’s own new one?

On 11th December the EU is likely to announce an NDC pledging a 55% cut by 2030. As its emissions are currently 20% down on the 1990 baseline, this implies it will cut emissions by 35 percentage points over the coming decade.

If the UK went for a 64% NDC, it would be pledging to cut by around 15 percentage points over the same period.

The precise number is complicated by the fact that the UK's emissions have so far been counted in the EU total and now won't be, but the basic point is clear: as things stand, the EU is set to cut emissions a lot faster than the UK over the coming decade.

Context is everything

All of the above indicates that the CCC is likely to recommend, and Government likely to adopt, a number higher than 64%. How much higher will depend on how government advisors and ministers balance the various factors at play – in particular, whether ministers choose to show they believe their own story, that fast decarbonisation brings economic benefits, and how much of a diplomatic downpayment they’re prepared to make not only with the small, developing countries that are key to successful COP26 hosting, but, now, with Joe Biden’s climate change-prioritising United States.

Numbers up to 68% and 70% are being mooted – and while something of that ilk wouldn’t satisfy all campaigners, it would be among the biggest numbers laid down by any nation and be clearly compatible with the national net zero goal.

As I hope I have shown here, the one thing the government absolutely must not do is announce a number in the absence of context. The number on its own tells us little – we need to know what it includes and how it's calculated in order to be able to judge the underlying ambition.

One hopes that Whitehall will ensure that ministers are adequately briefed on the background when they come to make the announcement, and take pains to explain the nuances in advance to whichever political journalist they plan to give the story to.

An NDC can contain much more than a pledge on emissions cutting. It can discuss sectoral targets, climate finance, adaptation both nationally and globally. But the 2030 emissions target is the big one. It carries a welter of implications, nationally and for COP26… and the Government only gets one chance to get it right.

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