This week climate minister Nick Smith and international negotiator Tim Groser start their 2020 emissions target roadshow, ostensibly taking the pulse of the nation on the question of what target New Zealand should commit to in the run-up to Copenhagen in December. Much of the argument will undoubtedly centre around the costs of taking action. The government has already signalled it wonâ€™t commit to targets likely to damage the economy, but there is a bigger question to consider — what emissions cuts does the world have to consider in order to avoid the worst effects of climate change, and how should New Zealand play its part? Any cost to the NZ economy is only a small part of that overall equation, and (arguably) not the most important. I want to examine what â€œthe scienceâ€ is telling us about a global goal and how we get there, and what that means for New Zealand. The leaflet produced to accompany the consultation process is pretty feeble in this respect, so I make no apologies for going into some detail here.
The first question is the hardest to answer: what level of atmospheric greenhouse gases can we live with? In UN-speak, the international community is committed to avoiding â€œdangerous anthropogenic interferenceâ€ with the climate, and this has come to mean a target of limiting warming to 2ÂºC above pre-industrial temperatures. However, there is no guarantee that 2ÂºC, even if it were achievable, would be â€œsafeâ€. Consider this graph:
This comes from a paper by Ramanathan & Feng last year (On avoiding dangerous anthropogenic interference with the climate system: formidable challenges ahead, PNAS Sept 2008, here), and shows the likely equilibrium warming (ie the eventual warming, as the climate system catches up over the course of decades) expected to result from 2005 greenhouse gas levels, if the cooling caused by man-made pollution (aerosols, the Asian Brown Cloud, for instance) is ignored. The peak of the probability curve lies at 2.4ÂºC above pre-industrial temperatures. Forget the aerosols for a moment (Iâ€™ll come back to them), the main point is that weâ€™re already well past our target. We can cut emissions all we want, but weâ€™re just adding to the eventual warming over 2ÂºC. Look at the danger points in blue above the curve. The Arctic summer ice is most vulnerable, followed by the Himalayan and Tibetan glaciers, then Greenland and so on. The take home message? There are already enough greenhouse gases in the atmosphere to cause significant and damaging change to the global climate system, and the reason weâ€™re not yet seeing the full effect is because our pollution of the atmosphere with aerosols is doing us a very big favour.
In the international negotiations under way for the successor to the Kyoto Protocol (Iâ€™ll call it K2), the 2 degree target has become associated with a 450 ppm CO2-equivalent â€œcapâ€ to atmospheric greenhouse gas concentrations. This is derived from the lowest set of greenhouse gas stabilisation scenarios considered by the IPCC (summarised in Table SPM6 of the AR4 synthesis report [PDF]), but in this context CO2-equivalent is not simply an expression of the total amount of greenhouse gases in the atmosphere, but factors in the cooling effect of aerosols. This can be referred to as CO2e(total), but gets shortened (somewhat confusingly) to plain old CO2e, and in 2005 this was 375 ppm. In other words, CO2e(total) is roughly the same number as CO2 (no e), because aerosols and pollution cancel out current levels of methane, nitrous oxide and other minor gases. Hereâ€™s the table from the IPCC:
The scenario being considered when the government refers to a commitment to 450 ppm CO2e is the top line in the table. Look at the column second from the left: it gives the peak concentration of CO2 (not e) considered — 400 ppm. Weâ€™re currently in the high 380s and rising at 2 ppm per year. Then look at the date when emissions have to peak. The range is 2000 – 2015. In other words, global emissions have to start declining over the next six years. Even if by some miracle we manage to achieve that, weâ€™re still committed to warming of up to 2.4ÂºC, and weâ€™re also relying on the continued cooling effects of aerosols… If that sounds like a tough ask, it is. I donâ€™t believe thereâ€™s any chance that the international community will get anywhere near to that sort of action — but itâ€™s where the negotiations are starting. The table also provides the most commonly used starting point for the target debate — where we need to be in 2050. The scenario suggests that global reductions of 50% to 85% will be required. In practice, this seems to have become 50% by 2050 for global emissions — an assumption at the optimistic end of the spectrum — and is what our National-led government had as its pre-election policy for New Zealand emissions.
Getting to national targets from global ones is not easy, however. You canâ€™t just ask everyone to cut by half, because developing countries — the biggest being China and India — point out quite correctly that the gases in the atmosphere causing the problem were not emitted by them. Current levels of CO2 have accumulated in the atmosphere as a result of fossil fuel burning in the developed world over the last 150 years, and only a tiny fraction of that has come from the less-developed countries. The argumentâ€™s simple. You got rich by emitting this stuff at no cost. If you want us to cut emissions, you need to give us room to grow. And so you arrive at the only game in town: contraction and convergence. In its purest form, this means setting a per capita emissions level for some point in the future, and then allowing countries to converge on that figure. Those with low emissions will be able to grow towards the new average, while the developed world will have to make cuts — and for the richest, they will have to be steep cuts. From this, we get to calls for developed nations to commit to cuts of 80% by 2050, and there are encouraging signs that the most powerful countries are ready to sign up to that. New Zealand, despite being tiny, is a part of that rich club, and has per capita emissions among the highest.
The question of 2020 targets flows on from consideration of emissions in 2050. If youâ€™re going to get to 80% or thereabouts, you need to start cutting back soon. In the real politik of K2 negotiations, the developing world has been calling for the richest nations to commit to targets of around 40% by 2020 in order to show good faith, and to encourage important new emitters like China and India to take on some serious emissions commitments. The governmentâ€™s overview leaflet provides a few examples, but omits the biggest — Britainâ€™s commitment to cuts of 34% by 2020. All fall short — far short in most cases — of 40%.
The cuts that are so far on offer also fall a long way short of achieving the 2ÂºC target the world has adopted. In this monthâ€™s NatureReports: Climate Change, Malte Meinshausen et al pull together all the commitments made to date, and plug them into a model to see what impact theyâ€™ll have.
As this figure from the paper shows, current commitments effectively guarantee a 2ÂºC rise by the middle of the century, and 3ÂºC or more by the end. The authors propose an alternative strategy, that of adopting a carbon budget — a cap on the total amount of carbon that can be emitted up to 2050. They propose a figure of one trillion tonnes of CO2, and their model shows that this would give a very good chance (75%) of meeting the 2ÂºC target. Unfortunately, though one trillion tonnes is certainly a big number, applying that to global emissions implies global cuts of 70% by 2050, and therefore significantly more than 80% by the developed world
OK, letâ€™s pause a while in our thoughts about targets, and return to the really hard question — what level of atmospheric greenhouse gases must we hit if weâ€™re to avoid the worst effects of warming. As weâ€™ve seen, even the lowest cap being considered does not guarantee we can come in under 2ÂºC, and there are aspects of dangerous change that might happen at or before that point. There are also positive feedbacks not considered in the IPCC scenarios — things like an increase in methane from melting permafrost and sea floor methane hydrates — that could kick in. At the same time, we have to remember that the sort of action that will reduce emissions will also tend to clean up aerosols (by cutting coal burning, for instance), “unmasking” some warming. Should we therefore be aiming under the 450 ppm CO2e that’s on the table at the moment? The answer, according to James Hansen, is yes. Hansenâ€™s 2008 paper, Target atmospheric CO2: where should humanity aim? [PDF] proposed 350 ppm CO2 (not e) as a â€œsafeâ€ upper limit — one that would maintain a planet with ice at both poles and a climate system at least similar to the one we have now. 350 ppm has since become an important number for people campaigning for action on climate change, and prompted Bill McKibben to set up 350.org as an organisation aiming to mobilise political thinking, to focus minds on something more ambitious than the cuts on the table in K2 negotiations. If politics is the art of the possible, then 350 ppm — which means going beyond 100% emissions cuts and actively removing carbon from the atmosphere — is probably too difficult, at least for the here and now. The fact that people are considering steeper targets does however carry an important message for policy makers here and overseas.
When deciding policy, itâ€™s helpful to have some idea of the balance of risk associated with any decision. If the climate risks were perfectly symmetrical, that is to say that the risk of there being no problem to address (and that therefore anything done is a waste of time and money) is equivalent to the risk that the problem will be worse than expected, then it would make sense to steer a cautious middle course. But the risks arenâ€™t symmetrical. The risk that the problem will go away of its own accord is essentially zero. There is a real possibility that the world will decide a cautious middle course (heading for something over 450 ppm CO2e) and then discover that itâ€™s really urgent that we head for 350 ppm at a wartime pace — perhaps because positive feedbacks are becoming all too obvious. At that point, having national policy in place that can respond quickly — or having aggressive targets in the first place — makes a lot of sense. This is the real strategic context for decision making on NZâ€™s emissions targets. It requires us to make an informed risk assessment — one based in the facts, not wishful thinking or economic forecasting — and take worst cases into account.
When you apply that logic to the National-led governmentâ€™s â€œ50 by 50â€ target it is obvious that it needs revision. At the very least it fails to match the long term targets of the club we want to part of — the developed world. As the most recent NZIER/Infometrics report noted, thatâ€™s a tent we very much want to be inside so that out exporters can continue to trade without carbon tariffs. At the very least, the government should adopt an 80% by 2050 target, and make contingency plans for that increasing to 90%. Better still would be to adopt the previous governmentâ€™s goal of carbon neutrality by the same date (preferably earlier).
With steeper long term cuts in mind, the focus for 2020 targets becomes clearer. This graph is taken from an earlier post about Solid Energyâ€™s suggestion that a massive investment in forestry could be used to create a national offset scheme:
The yellow line points to 80% by 2050, and (approximately) passes through 25% in 2020. Ignore the detail above the line. 25% looks to me to be the minimum credible target that New Zealand should adopt. It is a little more than the EU and a lot more than the US, but puts us on a credible emissions pathway. On the other hand, there is merit in aiming for a tougher target (350.org.nz and Greenpeace, for example, advocate 40% by 2020). This would put us in line with the demands of developing countries and the small island states in the Pacific, and could help us to play a bigger part in brokering a Copenhagen deal. Whatever the final target, of course, it is necessary to design credible policy that can get us there. Should we have different targets for different sectors, as the Greens have suggested? Thatâ€™s an open question as far as I am concerned. I havenâ€™t seen enough detail of what might be involved, and remain sceptical of moves to exempt or delay agriculture reducing its emissions. If there were to be a split target that gave agriculture (50% of our emissions, remember) a softer ride in the short term, then that would have to be balanced by steeper cuts in other sectors, or a more rapid expansion of forests as carbon sinks. There are therefore equity issues to be addressed, as well as questions relating to the sorts of policy levers a centre-right government is prepared to pull.
The governmentâ€™s information leaflet for the consultation process asks if NZ should consider conditional targets. The EU, for instance, has promised a 20% cut by 2020 whatever the outcome in Copenhagen, but will move to 30% if thereâ€™s agreement. Having said that I think the minimum credible target for NZ is 25%, that suggests that we could commit to, say, 40% in the event of a tough global deal, falling back to 25% in the event of failure. From our negotiator’s point of view, that ought to give our place at the table a little more weight and our exporters a place inside the tariff tent if a deal can’t be done.
I will be attending the consultation meeting in Christchurch on Wednesday. If I have the opportunity, I will try and articulate the above view, albeit somewhat more succinctly… But I am reminded of an old, old joke. With apologies to those of Irish heritage: A British couple are driving through the Irish countryside, trying to find the way to their hotel in Cork. They stop by a farmer on his tractor, and ask for directions. The farmer scratches his head and replies â€œAh now sir, if I was you, I wouldnâ€™t start from hereâ€. My feelings precisely.
And for the record: whatever the politics and practicalities of setting NZ’s targets, I endorse and support 350 ppm as a global target for atmospheric CO2. It strikes me as a difficult goal, but a prudent one.