Five years after Hurricane Katrina, the BP oil spill offers a chance to learn a lesson that we should have learned five years ago. Certainly, the two events differ in important ways – the hurricane itself was a force of nature, and the oil well blowout although powered by nature, was clearly the result of human activity. But the hurricane was not just a natural disaster. Its impact resulted from a series of human decisions and actions that exacerbated the hurricane’s effects and impaired the response effort. The lesson we should learn from these disasters is this: numbers may not lie, but they will fool us if we let them. Numbers – like those that predict how likely a disaster is, or the cost of taking steps to prevent a disaster – can be a helpful tool as we make decisions, like what kinds of levees to build and whether to allow oil drilling in a particular area. But the problem with numbers is the very thing we love most about them. They’re so precise. They seem to give us “the answer”.
The problem is that numbers appear much more certain than they are. They give you an answer, but it’s a mistake to assume the answer is the right one. There’s truth to the saying that statistics are like prisoners of war – torture them enough and they’ll tell you anything you want. For example, there are many different ways to calculate the odds of a disaster happening. As Professor Dan Farber of Berkeley has pointed out, the odds may be that a single oil well in the Gulf of Mexico will blow out only once every 8,000 years, which sounds pretty safe. But if there are 800 manned oil wells in the Gulf, that means that we should expect one blowout every ten years – a very different picture. The odds of Katrina hitting New Orleans were very low, but the odds that a hundred year storm would hit New Orleans at some point were quite high. So the fact that a catastrophe is of low probability is not an answer to the question ofwhether we want to risk the consequences. That requires an exercise of judgment. The odds that your house will burn down are very low. But most people buy homeowners insurance because of just that risk. When we make important policy decisions, we need to act the way prudent homeowners do – consider the worst case scenarios and decide if we’re willing to risk the downside.
If we do consider the worst case outcome, then, when we try to calculate how bad that worst case is and whether the cost of preventing it is worth it, numbers may again lead us astray. Both the BP blowout and Hurricane Katrina showed us that it is impossible to capture in a number – let alone a dollar figure – the cost of disasters of this scale. Yet it is extremely common for government officials to do just that. Agencies and private companies routinely engage in cost-benefit analysis to weigh the “benefits” of avoiding a disaster against the cost of taking extra safety measures. These numbers can be useful, but again, they are a dangerous crutch if we rely on them too heavily. They seem to provide us “the answer” – take the risk or don’t. But it’s clear that these numbers have lots of problems, as Lisa Heinzerling and Frank Ackerman elegantly showed in their book.
Among other problems, we’ve seen that numbers claiming to tally up the potential harm to humans and the environment inevitably leave way too much out. There’s no way to measure the cost of the massive human suffering, death, and dislocation from an event like Katrina, or the human and environmental cost of the BP oil spill. Yet when the Army Corps of Engineers made decisions about levees for New Orleans and BP made decisions about safety on the Deepwater Horizon, they were relying on just these types of flawed numbers. The Corps had to decide how high and strong and where to build the levees; BP decided not to perform a number of required tests and to cut corners to save money in the days and hours before the blowout. And as Robert Verchick points out in his recent book, Facing Catastrophe: Environmental Action for a Post-Katrina World, just as we fail to consider the costs of our actions’ impacts to health and the environment , when we do these cost-benefit calculations, we routinely fail to recognize the value of what is now being called green or natural infrastructure – like the wetlands that could have protected New Orleans from Katrina’s force, or the remarkable estuaries and wetlands that make the Gulf of Mexico an incredibly valuable fishery.
This illustrates another problem. The numbers – the risks of a disaster, the cost of avoiding a disaster – usually only paint a picture of the risks associated with one decision. Yet both the damage Katrina caused and the BP blowout were the product of many decisions. The Corps didn’t just build levees, it also constructed the Mississippi River Gulf Outlet that brought floodwaters into the heart of the city. And the Corps and other agencies made many decisions over a period of years that destroyed wetlands that could have protected the city from the hurricane’s force. And it’s now clear that a whole series of decisions by BP and the Minerals Management Service contributed to the risk of a blowout, not just one fatal error. But it’s almost impossible to calculate the costs or risks associated with these cumulative risks for a lot of reasons. And were we to try, the numbers about costs and benefits and risks become even less accurate as we try to add them all up.
The lesson these disasters teach is simple: the numbers don’t tell us everything we need to know. They are not a substitute for judgment. Why is this an important lesson to learn? And what can we do about it? Many Americans have responded to these tragedies with the message “never again.” If we really mean that, first, we need to stop allowing the numbers to fool us as individuals. Second, we need to demand that our government exercise judgment to protect us from this type of disaster rather than painting by numbers. We need laws that direct government officials and industry to take reasonable steps to avoid harm when faced with consequences that are disastrous or may be irreversible, what is often called a precautionary approach.
There is an even more urgent reason to wean ourselves from overreliance on numbers. We have spent years arguing about whether climate change is already happening, when it will happen, how likely it is to happen, how serious the impacts will be, and the cost of legislation to avoid the worst impacts – all arguments about the numbers. The argument for doing nothing relies entirely on numbers. But there are a lot of unknowns, so it’s hard even to assign a number that tells us how likely the worst case outcomes are. And we can’t come close to assigning a number to the devastating impacts of what people are now calling “mega-catastrophes” – truly unimaginable worst case scenarios – we are potentially facing. And since the worst case scenarios are so terrible, most of us would rather just ignore them, which the numbers conveniently allow us to do.
The public as well as government has allowed the numbers to lull us into inaction, to assure us that it’s okay to do nothing. But the reality is that there will never be a set of numbers we can look at that will tell us climate change is happening or has caused a particular catastrophe until there is no turning back. We may already be past that point. Whether we are or not, the prudent step would be to adopt a precautionary approach to the threat that climate change poses to our life, health, economy, and environment, not to mention that of our children. If we don’t, we may look back at the BP disaster and Katrina as wake up calls we ignored while we continued to paint by numbers. The result may not be the pretty picture we had hoped for.