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OPINIONScienceMarch 22, 2021

Dear British friends: spare us the gassy lectures on emissions

(Photo: Getty Images.)
(Photo: Getty Images.)

Britain seems unable to shake the patronising habit of reproaching its friends on climate ambition, despite being on factually weak grounds, write climate change experts David Frame and Adrian Macey.

New Zealanders have a pretty good grasp of the different ways short- and long-lived greenhouse gases contribute to warming. Many people overseas do not, to judge from some recent advice they have handed us. New Zealand’s split gas approach, which applies different rules to CO2 and methane emissions, shows the government has been listening to scientists. The IPCC pointed out that staying under 1.5°C did not require methane emissions going to zero. In their submissions on the Zero Carbon Act, NIWA and SCION, as well as PCE and the Productivity Commission, also argued for treating methane separately from CO2

Others’ grasp of the science appears weaker. Last year, Laura Clarke, UK High Commissioner, lectured us on our climate target, and we have recently had the Chair of the UK’s Climate Change Committee, Lord Deben, tell us that we are wrong to treat long-lived and short-lived gases separately.

They are on weak ground.

The UK has pledged to get to net zero emissions in order to halt its contribution to warming by 2045. This is a great goal. New Zealand – if it meets its net zero long-lived gas target for 2050, and the mid-point of its methane target – would halt its contribution to warming some time in the 2030s. This would also be a good effort.

But if New Zealand followed the UK advice it would mean that we – apparently alone – would actually have reduce our contribution to warming as well as being well ahead of the UK in halting it. 

What makes this a particularly odd position is that the United Kingdom of Great Britain and Northern Ireland is the world champion of per capita contributions to global warming. When contributions to climate change from major emitters are normalised per billion people, the UK manages to beat out even the United States for first place. If the UK had a billion people, it would be responsible for 0.54°C, ahead of the USA on 0.51°C, with Canada and Russia behind 0.41°C. 

We are probably somewhere around the latter number, if you count warming from fossil CO2 and the agricultural gases N2O and CH4 since 1840. That’s a high number, and a good reason to work hard at climate policy. Nevertheless, it would be bizarre for the all-time per capita warming champs to suggest that New Zealand alone do more than halt our warming. So Clarke’s comments more likely reflect faulty reasoning than an intention to single us out.

 Let’s take a look a piece of that UK reasoning. 

Lord Deben said of our split gas approach: “It doesn’t really wash. I think you have to be a bit careful about the idea that somehow or other, because it is short-lived compared with long-lived, it doesn’t really count in the same way.”

But it doesn’t really count in the same way. The IPCC made that point very clearly when they said

Climate forcers fall into two broad categories in terms of their impact on global temperature (Smith et al., 2012): long-lived GHGs, such as CO2 and nitrous oxide (N2O), whose warming impact depends primarily on the total cumulative amount emitted over the past century or the entire industrial epoch; and short-lived climate forcers (SLCFs), such as methane and black carbon, whose warming impact depends primarily on current and recent annual emission rates. These different dependencies affect the emissions reductions required of individual forcers to limit warming to 1.5°C or any other level.

So the gases really don’t count in the same way. They all count, but in different ways. And this implies they need to do different things to contribute to stopping climate change, as the IPCC also noted:

Sustained net zero anthropogenic emissions of CO2 and declining net anthropogenic non-CO2 radiative forcing over a multi-decade period would halt anthropogenic global warming over that period.

So Lord Deben is simply uninformed on this point. There are thousands of New Zealand – and UK – farmers who could put him right, or he could talk to the excellent UK scientists who have done pioneering work in this area. This happens to be an issue that matters to developing countries – think of rice farmers in Thailand or ranchers in Uruguay — who have significant proportions of methane in their emissions. 

Also wrong is Deben’s implication that New Zealand is departing from a global norm by moving away from a single, all-gas target. A recent paper from the group of Piers Forster, member of the UK CCC, observed:

NDCs [nationally determined contributions] vary in form and content. NDCs can be categorised by absolute targets, emission intensity targets, reductions from business as usual and policy measures. […] Coverage of pollutants is incomplete, with varying levels of clarity as to what is included. Where a metric is specified it is usually GWP100 from a single, but not necessarily the latest, IPCC assessment report. 

The paper goes on to show that the ambiguity in warming arising from NDCs relying on Deben’s preferred approach could amount to around a third of the remaining warming between current temperatures and the 1.5°C lower bound of the Paris temperature target. 

A European feature that the UK has not left behind post-Brexit is the propensity to somewhat patronisingly lecture their friends on climate ambition, it being assumed that the EU/UK is the gold standard for others to emulate. But all countries need to be cautious about claiming climate virtue. Take Norway – world leader in electric vehicles and renewable energy, strong targets, – but currently expanding oil drilling in the Arctic. We in New Zealand certainly deserve a hard time about our on-going emissions growth, not least in the transport sector — but this is a failure of policy, not targets.

When translated into additional warming, our long-term target is actually rather strong. If we achieve the current Zero Carbon Act range, the cooling from methane reductions more than masks the warming from the LLCPs by 2050. If New Zealand actually meets these targets, New Zealand will no longer be warming the climate by 2040. 

This may be unique among developed countries. Other countries have net zero targets but these countries’ emissions profiles are overwhelmingly dominated by LLCPs, so they will continue to warm the world until 2050. In our case, the extent of reductions in SLCPs, which reduce temperatures, more than offset the warming implied by our LLCP warming.

If we meet our targets, we stop adding to global warming earlier than the UK, Germany, and the EU, as well as Japan, Canada, Australia and the US. In New Zealand it is sometimes asserted that we have a duty to go beyond this, and to undo the warming we have already caused. If this is so, then it ought to occur as part of a broader initiative, explicit and applying to developed countries as a whole.

Understanding evolves, and the next report by the IPCC due this year will shed further light on these issues. In the meantime, we do not need to be too concerned about being singled out by Europeans who haven’t understood the science very well, or who generalise from their experiences without taking adequate account of respective capabilities and national circumstances. In the long run, they and global carbon accounting will catch up with the emerging science, and climate policy will reflect contributions to warming. 

An irony in all this is that it was British scientists who first observed that the targets in our Zero Carbon Act would imply an early finish to our warming. In contrast to the views expressed by Clarke and Lord Deben, Dr Michelle Cain — an emerging global leader in this field – said “New Zealand has prioritised science over institutional inertia in recognising the need to differentiate short-lived climate pollutants such as methane from cumulative pollutants such as CO2 in climate policy.”

UK and New Zealand scientists have a great record of working together on climate change. Perhaps British political figures could learn to listen more to their scientists – that’s a lesson New Zealand could happily share with them. 

Professor Dave Frame is Director of the New Zealand Climate Change Research Institute at Victoria University of Wellington. He has been a lead author on Intergovernmental Panel on Climate Change reports. Dr Adrian Macey is adjunct professor at the New Zealand Climate Change Research Institute and a senior associate of the Institute for Governance and Policy Studies. He was New Zealand’s first climate change ambassador, and chaired the UN Kyoto Protocol climate change negotiations in 2010-2011.

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