As the pandemic continues to dominate public politics around the world, a single number – the reproduction rate (R) – has become the focus of policy-making and public communication. Keeping R below 1.0 appears to be the primary objective of public health policy. In the case of climate change the number 2°C (or 1.5°C) operates in a similar way. And there is a recent proposal to create a single number by which to direct biodiversity policy – less than ‘20’ species extinctions per year. Governing complex phenomena through managing a single number is alluring. But as these three cases all show, it is misguided – and also dangerous.
The Allure of ‘The Number’
Climate politics have long been dominated by numbers: per capita emissions rates, global warming potentials, atmospheric concentration of CO2, global temperature. Over the last decade, policy-making around climate change has increasingly been directed by the number ‘2’ – limiting global temperature rise to no more than 2°C above the nineteenth century baseline.
Two degrees – ‘The Number’ – has gained extraordinary power in the science, politics and public discourse of climate change. Diplomats negotiate and campaigners protest around The Number, which also fixes the size of the carbon budget and, by extrapolation, the target date for net-zero emissions. This obsessive focus on The Number risk the dangers of climatism.
The ‘success’ of The Number for governing climate change has recently prompted Mark Rounsevell and colleagues to propose a “single 2°C-like target” for governing biodiversity. In their case The Number is proposed to be 20 – the maximum average annual allowable rate of species extinction over the next century. According to a recent Nature editorial, the justification for their proposal is to “break nearly two decades of failure” in global biodiversity governance,
In the case of the SARS-CoV-2 pandemic, The Number is a reproduction rate (R) of 1.0. R is a measure of the spread of infection in a population, but is a number which can only ever be imprecisely estimated and whose calculation rests on many assumptions. As David Adam has recently argued, fascination with R has turned into “unhealthy political and media fixation”.
The defence of The Number for public policy-making – whether climate change, biodiversity loss or a pandemic – is that it offers a simple, clear focus for political rhetoric and public communication. Indeed, Rounsevell and colleagues are explicit about this. The Number, they say, must be “easy to measure and communicate” and is intended to “galvanize both political will and public support”. This is why we have seen Boris Johnson repeatedly scrutinising and communicating R to set and defend the UK’s pandemic policies.
Why Single Numbers Lead To Bad Policies
In his book Fetishism and the Imagination, literary scholar David Simpson explains that fetishism occurs when the mind “ceases to realise that it has itself created the outward images or things to which subsequently it posits itself as in some sort of subservient relation”. Put more simply, a fetish is any created object or activity to which one becomes excessively or irrationally devoted.
The Number easily becomes a fetish. 2°C is already a fetish, in that it exerts excessive power over our imagination of the climatic future and is allowed to direct our policy-making. R is in danger of becoming a fetish in that all policies have to be justified or attacked according to whether they decease or increase R below or above 1.0. And if 20 is adopted as The Number for biodiversity management, I suggest that it too would quickly become a fetish by directing the conservation policy gaze solely in this direction.
Or if not a fetish, then The Number becomes a monster. Thus David Adam quotes Mark Woolhouse, an infectious diseases expert at University of Edinburgh, “We’re concerned that we’ve created a monster. R does not tell us what we need to know to manage this [pandemic].”
The problem with governing by The Number, as explained by Jerry Muller in The Tyranny of Metrics, is that it encourages goal displacement. Goal displacement occurs when attention becomes focused on hitting The Number, instead of attending to a wider range of more important public policy goals that are either not measured or not valorised.
In the case of climate change, The Number leads to a narrowing of policy horizons – limiting global temperature becomes the sine qua non of climate policy – whilst also opening the door to the Promethean hubris of solar geoengineering. The Number obscures the real reasons why we are concerned about climate change in the first place, for example people either dying or left without livelihoods because of climatic hazards or the ecosystems being damaged. The Number becomes the end or is assumed to be the only means of achieving multiple ends.
With regards to biodiversity I believe similar dangers await if Rounsevell and colleagues’ proposal is adopted. There are many other desirable outcomes of conservation and land use policy that are entirely missed by The Number 20, for example maintaining ecosystem functionality and sharing the benefits of biodiversity equitably.
And we are seeing in real-time the distortions in public health policy caused by fetishising R. As Adam again observes, “Too much attention to [R] could obscure the importance of other measures, such as trends in numbers of new infections, deaths and hospital admissions, and cohort surveys to see how many people in a population currently have the disease, or have already had it.”
Drawing the sting of climate change will not be achieved by limiting global temperature to 2°C. Minimising the total social burden of a pandemic will not be achieved by suppressing R to below 1.0. Effective conservation management cannot be delivered by simply limiting the annualised extinction rate below 20.
Why Good Policies Need Multiple Numbers
So if fetishising The Number leads to bad policies what do good policies need? They need multiple goals that recognise the diversity of the social and environmental goods and values that are threatened by the three scourges of pandemics, climate change and biodiversity loss. A multiplicity of policy objectives are needed. And they should be crafted so that they are deliberately incommensurable. They must not be collapsible to The Number.
Other indicators for climate governance have been proposed other than 2°C, for example ocean heat content, rates of energy decarbonisation, atmospheric CO2 concentration, global sea-level rise. Even better for climate would be foregrounding the UN’s 17 Sustainable Development Goals, for the reasons explained here.
In the case of the pandemic, it is essential to recognise those aspects of disease transmission that are not captured by R. These include local and regional variations in transmissions, the absolute numbers of potential spreaders, the nature and location of superspreaders.
Public health policy needs to focus on other numbers that have significant bearing on the total health burden and that can counter the magnetic pull of The Number. These would include, for example, cancer treatment rates, referrals to mental health services, unemployment rates, child-days of education lost … all being indicators which are heading in the wrong direction even while the focus is on controlling R.
One shouldn’t govern a pandemic through the reproduction rate, just as one should not govern climate change through global temperature nor biodiversity and ecosystem services through extinction rates. 1.0, 2°C and 20 are alluring numbers for politicians because of their simplicity.
But they are dangerous because they reduce the complex world to a single number. They point only in one direction.
Far better is to assert multiple goals – reflected in multiple numbers – which cultivates governance for clumsy solutions. We inhabit a plural, diverse world where scientific knowledge is always incomplete and revisionable. It is reflexive governance that is needed, guided by multiple and adaptive goals, rather than precision governance directed by The Number.
The best way of avoiding the dominant power of a fetish is to not grant it power over one’s imagination in the first place. Rounsevell and colleagues’ quest to create The Number for biodiversity management should be abandoned before it begins.
Mike Hulme, 9 July 2020, University of Cambridge
[Minor updates made 10 July]