As the ongoing devastation around Houston, TX continues to unfold from Hurricane Harvey flood waters, it is crucial that we begin learning lessons to better mitigate these risks in the future — for Houston and elsewhere.
Inevitably, both scientific and political discussions have turned their focus towards climate change, and to what degree changes in the climate may have played a role in this and other disasters.
Here, I do not intend to develop an argument about whether or not anthropogenic climate change is real or not, nor whether it has been adequately demonstrated scientifically (importantly, those are two separate issues).
Rather, this is an argument about how to best mitigate the risks of such disasters moving forward regardless of whether or not the culprit is climate change.
The crucial question is: given our current state of knowledge and capacity to act, what should we do?
There is a deep problem in our underestimation of extreme events under fat-tails. This problem is being both technically addressed and made famous by Nassim Taleb, and remains a central point regardless of climate change effects. We must get better at anticipating and addressing extreme events.
For the sake of discussion, let’s assume that climate change is real, and has caused an increase in the frequency of extreme weather events.
In that case, there are two pathways to addressing the problem and reducing the impact of extreme events:
1) Adjust the climate such that there are fewer extreme weather events
2) Adjust infrastructure and behavior to lessen the impact of extreme events
Let’s consider two aspects of each: (1) our capacity to affect, control, and engineer, and (2) the risks associated with such an undertaking.
Climate controllability and risks
The controllability of climate is low. This is most essentially due to our poor understanding of it. Most policy proposals intended to influence climate are focused on reduction of CO2 emissions. This is wise in the sense of the sensibility of a via negativa approach (that is, remove rather than add), however it suffers from our inability to control this variable immediately and directly (shall we use Houston as leverage for negotiating with China?). Moreover, there is uncertainty as to how effective this approach would be even if it were practically achievable.
Geo-engineering approaches are an alternative approach. These again suffer form our poor understanding of the system we are attempting to control or influence, and are likely to induce unintended consequences at the scale of the engineering, that is the global scale. There is the very real possibility we would make things worse, not better, with such an undertaking.
Infrastructure and behavior controllability and risks
The controllability of local infrastructure is high. It demands buy-in from a much smaller number of stakeholders. Construction methods are well-established and can be modeled reasonably well.
Moreover, controllability of behavior is high. Individuals and city planners can reduce the number of residents in known flood zones.
The risks associated with unintended consequences are at the local scale, so even where they occur, their impact will be bounded.
due to uncertainty and difficulty of buy in
due to uncertainty and global scale
due to well-established methodologies and achievable buy-in
due to well-established methodologies and local nature of intervention and higher-order effects
Scientific and policy discussions about the role of climate change are reasonable and appropriate following a devastating weather event like we are witnessing in Houston. However, they should not be the primary focus of effort and attention. We would be well-advised to learn how better craft our exposure to extreme events, and to better anticipate their eventual occurrence through non-naive risk analysis incorporating studies of tail-behavior.
These issues are not mutually exclusive, and I don’t intend to portray them as such. Nevertheless, for long-term mitigation of the impact of extreme events, it is vital to focus on our exposure to them rather than trying to control them.
In other words, don’t try to change the random variable X, instead change your exposure, f(X) (credit for this framing to Nassim Taleb).
For more on climate and precaution in the face of uncertainty, see our letter in Issues in Science and Technology here.