It might seem odd to find supporters of climate action debating the merits of a concept that science shows to be essential for halting climate change, and which is accordingly embedded at the heart of the defining global agreement.
Yet that is where we find ourselves with the concept of "net zero" – the point at which any remaining emissions of greenhouse gases are balanced with absorption, halting further warming of the climate.
The necessity of reaching net zero emissions globally is abundantly proven in science, and governments pledged in the 2015 Paris Agreement to achieve "a balance between anthropogenic emissions by sources and removals by sinks" in mid-century, in pursuit of holding global warming to 1.5 °C.
This language was included in the Paris Agreement only because of a determined push by activists and vulnerable countries. And it's hard to think of a more successful recent example of activists' ideas changing the terms of debate.
In two years, the number of nations, sub-national governments and corporates setting net zero targets has mushroomed, with coverage leaping from 16 percent of global GDP in June 2019 to two-thirds now. It is no exaggeration to say that net zero is now the defining lens through which many governments, businesses, NGOs and other types of entity view decarbonization.
However, activists are not universally celebrating. Many have reacted by pointing out the flaws in some net zero targets, with particular fire turned on oil and gas companies that plan to pay for offsets in place of dealing with the emissions caused by burning their product.
In some cases, concerns about the implementation of net zero targets turn into criticism of the concept itself. Recently three climate change academics including former IPCC chair Bob Watson described net zero as a "fantasy" and a "trap", while Greta Thunberg said that "these distant targets" are about "making it seem like we're acting without having to change".
Net zero commitments: a mixed picture
To be credible, an entity proclaiming a net zero target should have certain measures of robustness in place: at the very least, a high-level commitment, a published plan, immediate emission-cutting measures and an annual reporting mechanism. It must ensure that all its attributable emissions are covered, and that any "netting" uses high-quality, verified and permanent removals.
In March 2021 we were among researchers publishing the first analysis of the robustness of net zero commitments made across 4,000+ national and sub-national governments and companies, accounting for 80 percent of global emissions.
We found the picture is mixed: while most entities with a net zero target do have some robustness measures in place such as interim targets (60 percent) and a reporting mechanism (62 percent), others do not. The picture on offsets (paying for carbon credits from actions elsewhere) is particularly concerning, with only 23 percent of entities either ruling them out or putting restrictions on their use.
Does this mean that the concept of net zero as a defining frame for decarbonization is itself a fantasy? We would argue that it absolutely does not.
The rapidly growing suite of net zero pledges comes with a coherent theory of change. Firstly, if an entity is serious, it will follow its pledge by putting robust measures in place, beginning with immediate actions to cut emissions: not doing so will quickly open up the entity in question to accusations that it is not serious.
Secondly, pledging a target means that the entity can be held to account by voters, shareholders or customers. Thirdly, to demonstrate credibility it may have to apply for accreditation from an impartial mechanism such as the science-based targets initiative, which can validate whether its plan is realistic.
Fourthly, such accreditation mechanisms evolve over time to follow the science. For example, the UN-backed Race to Zero recently published upgraded criteria (in which we were involved); further annual strengthenings await.
Each of these four steps makes the commitment more concrete – and if it is not serious, exposes that clearly.
Signs that net zero targets lead to stronger action
In Germany, the constitutional court has just ordered the government to increase its near-term action to ensure that the costs of meeting net zero do not fall disproportionately on future generations.
A survey of the new Nationally Determined Contributions (NDCs) that nations are due to submit before the next UN climate summit, COP26, shows that 32 of the 101 countries with net zero targets have enhanced their NDC, compared with 11 of 90 countries without a net zero target.
Climate advocates are right to highlight the loose nature of some pledges, particularly from fossil fuel corporates. Such scrutiny is necessary to protect the science from greenwash. As Thunberg subsequently tweeted, "the problem is of course not the net zero targets themselves, but that they're being used as excuses to postpone real action".
If you can't see that "net zero targets" risk leading to these things, then you either don't understand the problem or you have a very clear agenda.— Greta Thunberg (@GretaThunberg) April 27, 2021
The problem is of course not the "net zero targets" themselves, but that they're being used as excuses to postpone real action.
This is a real danger. If we allow disingenuous uses of net zero to discredit the concept as a whole, we risk giving up the hard-won gains secured by activists and vulnerable countries in Paris in 2015.
Rather than tarring all net zero pledges with the same critical brush, we would advocate differentiating serious targets from those set for greenwashing. Not all entities will embark on their journey to net zero with a fully fledged plan, but they should quickly clarify how they will reach their target: those that do so deserve plaudits if their plans are robust and viable, while those with unviable or absent plans deserve criticism.
Despite the imperfections, widespread strengthening of net zero targets, specifically to generate steep emission cuts in the next decade, offers the most viable route to implementing the Paris Agreement and so preventing the most dangerous impacts of climate change. We should get net zero right – not get rid.
Richard Black, Honorary Research Fellow, Grantham Institute, Imperial College London; Steve Smith, Executive Director, Oxford Net Zero, University of Oxford, and Thomas Hale, Associate Professor in Public Policy, University of Oxford.