The notion of the black swan came from the traditional belief that all swans were white. When a single black swan was found, so the story goes, the swan world was transformed. If you haven’t already, you might want to read Nassim Nicholas Taleb’s excellent book, The Black Swan. Hint: it’s not about swans.
Chaos theory is also tied up in this concept.
The important truth of chaos theory for our purposes is that we are inherently limited in what we can predict about a complex system. Two good examples of complex systems are the stock market and the weather. In both cases, thousands of events can affect outcomes. Suppose some minor dealer in Iowa decides to sell a certain stock. The event is meaningless in a market where billions of dollars are traded within seconds. But suppose someone elsewhere noticed the sale, and maybe another one like it, and decided to follow suit. Probably nothing would happen, but we cannot say that it wouldn’t cascade into major changes in the market, maybe even a crash. We simply can’t predict, any more than we can predict whether that fabled South American butterfly wing would lead to tornadoes in the Midwest. In fact, we can only tell in retrospect what things had an effect.
The weather is similarly complex. That’s why weather forecasts are nominally accurate for less than a week. After that, many possibilities could come about, and we have no way to tell which ones would materialize.
Climate change is like that too, only much more complex. Every day we get more data, barge-loads of it, which increases our predictive powers, but the elements themselves that rule global climate number in the millions. Not only can we not measure them all, let alone measure them accurately, their immense complexity is by itself enough to sharply limit our predictive abilities.
In the case of climate change, the daily barge-loads of data tell us where things are going, but not how or when. We are left to imagine the frightening detail.
And that’s before a black swan presents itself.
We don’t know what a specific climate black swan might be because “black swans” cannot be foretold. That’s what black swan means. Let me suggest a possibility.
Greenland has been covered by ice a couple of miles thick for more than 100,000 years. That’s a long time, half of our existence as a species. Now, there is no reason at present to suppose a disastrous event in the Greenland ice sheet is imminent, but worried scientists point out that meltwater courses over the entire surface, forming fast rivers that disappear into holes in the ice. But suppose this melting accelerated because of some other event, which itself might occur because of a previous third change, which might… You see what I mean. What would be the “butterfly wing” that would lead to a catastrophic change in the Greenland ice cap?
Suppose the ice cap became weakened at some crucial spot we didn’t know about, and a major chunk of Greenland ice slid into the ocean. We have no reason to expect this to happen, but if it did, it would be a true black swan event. This black swan would precipitate catastrophic change that affected the entire planet. What’s more, it might even become a cascade, causing, say, similar changes at the South Pole, where the ice cover is bigger, and stability is already fading fast.
If you haven’t already seen it, you must watch the biggest glacial calving event in history, from a large glacier in Greenland. Over a period of 75 minutes, an area the size of lower Manhattan roared into the sea, spewing chunks of ice several times larger than the biggest skyscrapers there, some of them suddenly jutting many hundreds of feet into the sky. It’s astonishing, frightening, but this event was nowhere close to the scale of the black swan event I imagined for you.
Such black swans would not be limited to melting ice, of course. Something like sudden temperature elevation in agricultural areas, or die off of rainforest trees might be black swan events, or cause a black swan.
What is frightening about climate change is that we have created instability and uncertainty everywhere on the surface of our little blue planet. We can hope and pray that we as a species are wise enough to realize how thin the ice we cross has become, so that we can back quickly away to keep such catastrophic events at bay. Our wisdom so far is not reassuring.