# Bevy of Black Swans

Cliff Mass likes to refer to the recent heat wave in the Pacific Northwest as a “black swan” event. The term refers to “Black Swan Theory,” developed by Nassim Nicholas Taleb, which wikipedia describes as a “metaphor that describes an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight.

Here’s how Taleb himself defines a “black swan” event:

What we call here a Black Swan (and capitalize it) is an event with the following three attributes.

First, it is an outlier, as it lies outside the realm of regular expectations, because nothing in the past can convincingly point to its possibility. Second, it carries an extreme ‘impact’. Third, in spite of its outlier status, human nature makes us concoct explanations for its occurrence after the fact, making it explainable and predictable.

I stop and summarize the triplet: rarity, extreme ‘impact’, and retrospective (though not prospective) predictability. A small number of Black Swans explains almost everything in our world, from the success of ideas and religions, to the dynamics of historical events, to elements of our own personal lives.

I stop and emphasize the phrase “not prospective.”

Taleb means that there’s only retrospective explanation, there’s an absence of prospective (i.e. predictive) explanation. I’d like to remind Cliff Mass that extreme heat waves, of greater frequency and severity than seen before, has been a prediction of climate change science for decades. Therefore, according to Taleb’s own definition, the recent heat wave in the Pacific Northwest is not a black swan event.

Taleb emphasizes the folly of “explaining” an extreme event with major effect which nobody saw coming, as though we should have known all along. He’s got a point. I’ll emphasize the folly of the opposite mistake: to use “Black Swan Theory” to dismiss what scientists have been warning us about for decades, as nothing but an unpredictable outlier.

Perhaps Cliff Mass will insist that the heat wave in the Pacific Northwest was so severe, that nobody predicted a heat wave this strong. It was so much an outlier, we have to call it a “Black Swan.”

If we’re going to do that … then there are a whole lot of Black Swans popping up these days. All over the world. With a frequency, and of a blackness, far beyond what we’ve seen before, a veritable population explosion of Black Swans. The heat wave in the Pacific Northwest is far from the only example, but it is the one which Cliff Mass can’t ignore.

This blog is made possible by readers like you; join others by donating at My Wee Dragon.

### 11 responses to “Bevy of Black Swans”

1. Dan Riley

Perhaps we could call these black peppered moth events, after the moths that drastically changed their color distribution as a response to environmental changes.

2. Philippe Chantreau

So far this year we are at several heat waves around the Northern hemisphere, with all time high records in US, Canada, Northern Ireland, Turkey, Northern Japan.
This is accompanied in the Western US by extreme drought, water shortages and wildfires of which the largest is now 400,000 acres (Bootleg fire, OR).
We also have seen multiple extreme rain events with catastrophic floods in Europe, China, Australia, New-Zealand.
Australia has been hit with unique severity, getting several years of severe droughts and catastrophic fires, followed now by equally catastrophic rains and flooding.
There is probably no good way to assert the probability of such a combination of events to happen in the first half of any given year but really, who cares?
As Tamino pointed, what is unfolding is exactly what the scientists who know what they’re talking about predicted literally decades ago.

3. Philippe Chantreau

How do you call a large flock of Black Swans?

4. Tom Dayton

In a new post, Mass doubled down on his previous assertion that “This situation is a good example of the golden rule of climate attribution: the more unusual and extreme the event, the greater the proportion of the event is due to natural variability rather than global warming.”

At some point, bias and ignorance are inadequate explanations for such persistent and elementary wrongness.

• b fagan

Tom, I’d never paid any attention to him before, but I read Mass’ new post twice, and was struck by how carefully he set HIS definition of the effect that warming would have on precipitation (a foot more water behind the dam due to annual average), simply to then pretend he was obliged to attribute the bulk of an extraordinary flood as simply too much natural variability at once.

It could be a really handy technique to deflect attention.
a – redefine and distort the potential effect of an aspect of climate change
b – use that minimized version for your own, customized Mis-attribution analysis when events clearly imply the climate is changing.

Is he trying to create a new version of the Uncertainty Monster?

• Thomas P

When I see statements like that I always think of the old movie ‘Arsenic and old lace’ where a murderer is bragging about how many people he have killed:
Dr. Einstein: You cannot count the one in South Bend. He died of pneumonia!
Jonathan Brewster: He wouldn’t have died of pneumonia if I hadn’t shot him!

• b fagan

Off to Panama again!

5. Al Rodger

The ‘Black Swan’ concept begins with Taleb’s 2007 book which kicks off considering their existence within the world of the financial markets, perhaps exemplifying the concept’s dodgy origins. Further, its originator, Taleb, is descibed as ‘shipwrecking’ his concept when trying to show it in the ‘real-wold’ settings. by made up fake people/events to illustrate the alleged ‘real-world’ existence of ‘Black Swan’ events rather than using proper ‘real-world’ examples. He has also been a bit mouthy about climate change being recorded in an interview as saying “I don’t want to mess with Mother Nature. I don’t believe that carbon thing is necessarily anthropogenic.”

I think the first application of the term ‘Black Swan’ with regard to AGW was an item from 2009 by a Michael Ferrari describing how climate has an impact on financial markets and thus it is worth anticipating unexpected outlier events which Ferrari correctly describes saying “Empirically, these patterns should not be considered Black Swans.”

So the dodgy ‘Black Swan’ concept was just the sort thing for swivel-eyed denialists to adopt within their dodgy argument.

6. I think the context of using conditional probabilities to estimate the likelihood of a biased coin in a run of tosses is a good setting for Black Swan considerations. Consider an experiment where we are jointly estimating the biasedness value for a coin, that is, $p(\text{head}|\text{run of 1000 heads})$. But given an informative prior $\pi(head)$ which admits the possibility of bias in the coin, with the observation of 1000 heads in a run, more mass density is going to show up in the posterior density on the side of a biased head than exactly on $p(\text{head}|\text{run of 1000 heads}) = 0.5$.

Accordingly, could a cluster of extreme events be due to natural variability? Or or Long Range Dependence? Theoretically, yes. But irconically that’s too complicated a possibility. It’s vastly more likely that there really is something to the mechanics of greenhouse gas warming, lapse rates, and the predictions of climate models.

7. STK

Exactly, these aren’t black swans, they’re the less commonly-known “grey rhino” –

A “gray rhino” is a highly probable, high impact yet neglected threat: kin to both the elephant in the room and the improbable and unforeseeable black swan. Gray rhinos are not random surprises, but occur after a series of warnings and visible evidence. The bursting of the housing bubble in 2008, the devastating aftermath of Hurricane Katrina and other natural disasters, the new digital technologies that upended the media world, the fall of the Soviet Union…all were evident well in advance.
https://www.wucker.com/writing/the-gray-rhino/