Communicating risk and uncertainty in science
Speech by Sir Mark Walport to the Foundation for Science and Technology on the challenge of communicating the uncertainty in risk estimates to policy makers.
There are several aspects of risk that have to be borne in mind by scientists who advise government. The first concerns the terminology involved, specifically the distinction between risk and hazard, 2 terms which are often confused. Second, scientists must recognise that policy makers and, indeed, the public, look at issues through different ‘lenses’, including different values. Then, too, there is undoubtedly the challenge of clear communication.
The assessment of risk is at the heart of the work of the Government Office for Science. Among the urgent issues currently being studied by both the US and UK governments are the risks associated with space weather, specifically the possibility of another solar storm like the 1859 Carrington Event. What would be the consequences for telecommunications, electrical grids and satellites?
Flooding is extremely topical with questions being raised about the consequences of building on flood plains and the appropriate level of spending to make such housing safe to live in.
Those are natural hazards but there are also human threats - terrorism, emissions of carbon dioxide and other pollutants into the environment, for example.
The government produces a freely available National Risk Register. A simple and effective way to represent risk is to classify each according to both impact and likelihood. Risk registers can be utilised to help prevent undesirable events, as well as to mitigate, manage and clear up when they do occur. But can they also be used to decide the relative investment that one allocates to different threats? Can they provide a basis for evaluating investment options? Decisions have to be made about how public money should be spent, after all.
Risk and hazard
Risk is commonly defined as the product of hazard exposure and vulnerability. Yet there is a great deal of confusion about the terms ‘risk’ and ‘hazard’. The issue of pesticides illustrates this clearly.
The question involves pesticides, pests and pollinating insects. The EU has recently imposed a moratorium on the use of neo-nicotinoid pesticides in agriculture, but the UK opposed this decision. The issue is not whether neonicotinoid pesticides are hazardous to insects: they are designed to be extremely hazardous, hence the term ‘insecticides’! They should, though, kill the undesirable insects while having limited impact on the insects that society wants to encourage.
The key question, then, is: “Under field conditions, is the exposure of other pollinating insects to these substances unacceptable?”
If exposure is at a safe level, then the insecticide will achieve its aim, killing the unwanted insect, not the useful one. The problem, to be frank, is that the evidence available is not robust enough to answer this question.
In laboratory conditions it is possible to show how neo-nicotinoidal insecticides can have deleterious effects on bumblebees, honey bees and other insects. What is lacking is clear evidence that, when applied according to the manufacturers’ guidance, they still have toxic effects in the field.
This distinction between hazard (and many things are hazardous) and risk is a continuing challenge for regulators. There is a tendency to regulate by hazard rather than by risk.
With new technologies, there is the further issue of communication about the risks involved. There are risks associated with almost everything humans do: they have to be managed and not ducked. Unfortunately, there is too often a tendency to duck.
In the case of Genetically Modified Organisms (GMOs), the mistake was to talk about them in a generic sense, yet there is nothing generic about a GMO. By focussing on the specific purpose, the individual organism and the nature of the genetic modification, there can be a sensible discussions about hazard and risk. It is not helpful to treat a whole technology as though it poses a single risk.
The Precautionary Principle
The Precautionary Principle is often brought into these discussions. It is assumed to mean that if there is any possibility of anything harmful, then that choice should be avoided. However, this is only one interpretation.
The UK government interprets the EU communication on the Precautionary Principle as requiring the fullest possible scientific evaluation of the hazards, exposure and vulnerabilities associated with a particular choice. A decision to act or not is preceded by an evaluation not only of the hazard but also the consequences of not proceeding along this path – in other words, the consequences of inaction. The Precautionary Principle should be transparent; it must take into account the general principles of risk management (in other words being proportionate), it will involve thorough risk/benefit and cost/benefit analyses and include constant review as new evidence emerges.
Unfortunately, regulators are frequently subjected to asymmetric incentives. There will be trouble if something is allowed to go forward which causes harm. However, there is no consequence for stopping something happening that would actually have brought benefit. This is a profound problem because it means that the incentive system is loaded entirely in one direction. Society should recognise that harm can frequently flow from omission as much as commission.
The confusion between risk and hazard can lead to different parties in an argument talking at cross-purposes without realising it. The fracking debate is a very good example. On the one hand, there are legitimate scientific and engineering questions about hydraulic fracturing: will there be any damage to aquifer zones by leakage of contaminated fluids; will there be significant side effects; will fugitive methane be released? These are key questions. Now, the Royal Academy of Engineering has concluded that all of these concerns can be managed where best practice is applied.
Go and talk to the protestors in Sussex, though, and there is actually a different conversation taking place. Some of these people are totally opposed to the oil and gas industry, some simply do not like capitalism, while others are motivated by a ‘not in my back yard’ attitude.
To communicate effectively, it is necessary to look through the ‘different lenses’ that various parties have on these issues. Studies show that about threequarters of the population are fairly or very concerned about climate change; they believe the UK should reduce its use of fossil fuels. A similar proportion are concerned that electricity and gas will become unaffordable and a very similar proportion again (70 to 80%) are concerned about energy security. These are the 3 policy lenses which are important, of course, when talking about energy.
There is then work to be done in exploring people’s values around, on the one hand, the finite nature of resources, linked to people’s feelings about waste, efficiency, environmental protection, social justice and fairness. On the other there are the issues of availability and affordability, reliability, safety, as well as freedom of choice.
It is vital to understand the nature and interplay of these issues seen through different lenses if there is to be a sensible and constructive debate.