Uncertainty, coordination and climate change

Today I spent a couple hours reading two papers authored by Scott Barrett, an environmental economist. One paper is “Climate treaties and approaching catastrophes” and the other (co-authored with Astrid Dannenberg) is “Sensitivity of collective action to uncertainty about climate tipping points”. The first paper is purely theoretical, and the latter has theory and an economic experiment.

Barrett’s focus in these papers is on climate change treaties. Climate change treaties are a challenge because costs of CO2 pollution are externalized, but countries are inclined to ‘free ride’ since there is no global government to punish non-signatories, or countries that fail to meet their commitments. For this reason, many argue that global-scale climate treaties are doomed to fail.

These papers show that coordination can work to address this climate treaty problem. Coordination occurs when actors work in their self-interest towards a goal that is collectively beneficial. When coordination is possible, there is no need for an enforcement mechanism; the treaties work because adhering to commitments are in the private interests of actors.

A number of conditions must exist to see effective coordination in abating climate change, but the one of Barrett’s focus is the reduction of uncertainty at the threshold which a climate catastrophe would occur. In short, as uncertainty in the threshold gets smaller, the more likely that an actor will follow through with abatement measures–like reducing CO2 emissions. Provided the uncertainty is small enough (in proportion to the damages resulting from climate change, and inversely proportional to the difference between costly abatement and the benefits of climate change) then actors will choose to take measures to avoid catastrophe.

Lucky for you, I wrote some R code that you can use to experiment with the model he proposes!

In addition to demonstrating this theoretically, Barret and his co-author use some hypothetical choice experiments to test this theory in the lab. The experimental results are fairly consistent with their theoretical findings; the authors found that most people would choose to abate when the catastrophic tipping point is certain, and nobody would abate when it is very uncertain.

What this research shows is the importance of reducing scientific uncertainty, and specifically, that reducing uncertainty about thresholds of climate catastrophes may be key to getting useful and effective climate treaties.

Data, infant mortality and anti-abortion activism

The following question crossed my mind recently: how many lives are lost from excess infant mortality?

I asked this question because I wondered if anti-abortion activists couldn’t better spend their time saving the lives of children that died in their first year of life, rather than protesting at abortion clinics. Saving the life of a child who has been born seems like an easier political task, and will almost certainly be more effective.

We have a pretty good sense that this is theoretically possible because of the considerable variation in infant mortality that exists worldwide. Most poor countries have high infant mortality rates (IMR), and most rich countries have low infant mortality rates. There are a number of countries in Africa with IMR above 50 per 1000 live births (meaning 50 children die in their first year for every 1000 live births). There are rich countries with IMR below 5. The difference between these numbers–roughly 45 per 1000 births–tells us that preventing infant death could be very impactful.

In the US, there is variation in IMR across ethnic communities. The IMR among African Americans is 11.4, and 4.9 among whites. All of these babies are being born in the US, but white babies are much more likely to survive past 1 year of age. Preventing infant deaths in African American and other marginalised communities would save lives without the controversy.

In Canada, the IMR for the Inuit population is a shocking 17.7, three times the national average. Improvements to maternal care and access to quality health care in remote rural areas would save the lives of many living infants. Given that there is little popular or political appetite for outlawing abortion in Canada, reducing IMR among the Inuit seems infinitely more productive way to spend time for people who are concerned with preserving lives of children.

Globally, the potential numbers of lives saved would be much greater. I used World Bank data to estimate the number of infant lives that could be saved worldwide if we lowered IMR to 5 per 1000 for in every country in the world that currently has an IMR greater than 5. You can download the R code here. According to these calculations, we could save around 3.6 million children every year by lowering IMR to 5.

3.6 million children every year!

Practical solutions for lowering infant deaths in poor countries are fairly well known. Worldwide, many infant deaths occur because of preventable infection. Most of these infections could probably be treated with investments in medical infrastructure and better access to antibiotics. Other deaths are caused by an absence of simple medical interventions and lack of training. It seems that anti-abortion activists could put their time into lobbying pharmaceutical companies to increase affordable access to antibiotics in developing countries, or improving access to maternal care in the developing world.

Closer to home, we could do more to increase access to health care and support mothers living in poverty, particularly in rural and remote areas. There are many lives to save, and best of all, none of them come with legal wrangling or political and social controversy. It seems that anyone who genuinely cares about saving lives for their own sake could do a lot about it without entering the quagmire of anti-abortion activism.

No room for human error

Jaskirat Singh Sidhu caused the bus crash in Saskatchewan that killed over a dozen people. It’s a tragic event that received lots of media attention, in Canada, and elsewhere. The judge of the case recently handed Sidhu an 8-year prison term as punishment for causing the crash. A public transcript of the judgement can be found here.

Here is a list of important facts concerning this case.

  1. Sidhu pleaded guilty to causing a collision that killed 16 people and injured 13. Specifically, he pleaded guilty to 16 counts of dangerous driving causing death, and 13 counts of dangerous driving causing bodily harm. These are criminal code offences in Canada, with a maximum sentence of 10 years in jail.
  2. Sidhu expressed remorse, and there is no evidence of any intent to have caused this collision.
  3. There were multiple stop sign warnings indicating that Sidhu was required to stop at the intersection.
  4. The visibility was not an issue (due to weather or time of day)
  5. Sidhu was not speeding at the time of the collision.

Here is some other information that is not specific to this case, but is important for context, and available to anyone who cares to look.

  1. Many drivers have driven through stop signs and other traffic controls. If your personal experiences don’t convince you of this, the empirical evidence is abundant. In a U.S. study a few years ago, 13% of drivers at a stop sign controlled intersection did not stop at all and 52% came to only a rolling stop [1]. Older data from Canada showed similar numbers [2]. In a 2009 study of older drivers in the US, almost 16% of drivers over 66 years of age failed to stop at a stop sign at least once over a 5 day period [3]. Stop sign violations are second only to speeding violations on a per-kilometre-travelled basis [4], and are responsible for between 5 and 10% of collisions involving casualties [5].
  2. Stop signs are not as effective as common sense might dictate. Multiple signs might even be counter productive, and changing controls from yield to stop may even increase risk of motor vehicle collision [7]. Some have argued that signs are a distraction, that we may become desensitised to them the more of them that there are, and we’re better off reducing the number and size of traffic controls [8,9].

On balance, this information shows that humans make mistakes–both in missing or ignoring traffic controls, and in assuming that traffic controls necessarily increase safety. Sidhu’s responsibility for the collision is not in question; what is in question is what punishment is appropriate when someone makes a fairly common mistake that leads to an incredibly unlikely and tragic outcome?

The judge’s view is to punish him with a jail sentence of 8 years. This is below the maximum. My gut tells me this is unfair, but I am not a judge, so I’m not sure my gut matters.

However, I do take exception with some of the reasoning offered by the judge. In her sentence ruling, the judge argued that it was “baffling and incomprehensible”  that Sidhu missed the stop signs that were posted. As noted above, it should be neither baffling nor incomprehensible to anyone who cares to consult research on the efficacy of stop signs, or reads local newspapers [10].

Humans make mistakes. Sidhu’s mistake was not unique, not uncommon, and not malicious. What was uncommon was the convergence of other facts surrounding this event–that a bus full of teenagers happened to be in the wrong place at the wrong time.

The fact that the judge was motivated to sentence him to 8-years at least in part because she can’t imagine how a person could not have seen the stop signs is simply ignorant. It is clearly possible for a person to make this kind of mistake, as well as a variety of other perceptual and judgement errors that leads a person to run through a rural intersection without stopping. It happens all the time.

Another problem I have with the reasoning of the sentencing seems to have been the magnitude of harm. In her decision, the judge writes “a sentence of more than six years is mandated due to the horrific consequences of his actions.”

On the one hand, the judge acknowledges that Sidhu had no intent to harm, but was simply very negligent and inattentive. On the other hand, she is holding him responsible for the gravity of the outcome; had he been equally inattentive but killed one person, it seems that he would have received a shorter sentence.

In legal circles this may make sense, but to me it seems illogical. Sidhu’s crime was dangerous driving, and his dangerous driving directly increased the probability of causing a collision. He is accountable for that. However, this increase in probability had no corresponding impact on the consequences once a collision occurs; the bus full of young hockey players would still have been at that intersection whether or not he stepped on the brakes in time to avoid the collision.

Obviously the bus driver and victims of the collision were not at fault here. But assigning fault to Sidhu that is proportional to the loss of life suggests that he was responsible for the severity of the consequences, in spite of him having no control over them. I’d understand this conclusion if the judge ruled that he intended to cause the collision. However, she accepts that Sidhu “did not deliberately drive through the intersection.”


Something in me is unsettled by the fact that Sidhu is being punished harshly partly because of the number of lives lost in the this tragic event. He was negligent, and punishment may be required, but was he really so much more negligent than the average truck driver, or even the average person?

I’d like to think all of us can relate to making mistakes. I guess we should just feel lucky that most of our mistakes are very unlikely to harm anyone, as it seems that the courts have little tolerance for human error.