How Does the Butterfly Effect Work?

The term 'butterfly effect' was coined in the 1960s to help explain how complicated weather is, but it can be applied to many complex or chaotic systems. Learn more about the butterfly effect (and what we often get wrong about it) in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeart Radio, Hey
brain Stuff laurenvog Obam here. The butterfly effect isn't just
a movie from two thousand four. It's the idea that small,
seemingly trivial events may ultimately result in something with much
larger consequences. In other words, that small things have non

(00:22):
linear impacts on very complex systems. For instance, when a
butterfly flaps its wings in New York, that tiny change
in air pressure could eventually cause a cyclone in Beijing.
In the aforementioned film, Ashton Kusher's character finds a way
to travel back in time to his childhood. Every time
he makes the journey, though, he does small things differently,

(00:45):
and those tiny changes wind up having major and horrifying
effects on his adult life. The term butterfly effect was
coined the nineteen sixties by Edward Lawrenz, a meteorology professor
at the Massachusetts Institute of Technology who was studying weather
path turns. He devised a model demonstrating that if you
compare two starting points indicating current weather that are near

(01:06):
each other, they'll soon drift apart, and later one area
could wind up with severe storms while the other is
calm at the time, Whether satisticians thought you should be
able to predict future weather based on looking at historical
records to see what had happened when conditions were the
same as they are now, Lorenz was skeptical. He was

(01:28):
running a computer program to test various weather simulations, and
he discovered that rounding off one variable from zero point
five zero six one to seven to zero point five
zero six dramatically changed the two months of weather predictions
in his simulation. His point was that long range weather
forecasting was virtually impossible, in large part because humans don't

(01:51):
have the ability to measure nature's incredible complexity. There are
simply too many minute variables that can act as pivot points,
cascading into much bigger consequences. As The Boston Globe wrote,
the innumerable interconnections of nature, Lorenz noted, mean a butterfly's
flap could cause a tornado, or, for all we know,

(02:11):
could prevent one. Similarly, should we make even a tiny
alteration to nature quote, we shall never know what would
have happened if we had not disturbed it, since subsequent
changes are too complex and entangled to restore a previous state.
So while people often think the butterfly effect means that
tiny changes can have big consequences, and that we can

(02:34):
track this progression to see what change caused. What Lorenz
was trying to say that we can't track those changes,
and we don't really know exactly what would cause a
weather pattern to go one way or another. Lorenz called
this sensitive dependence on initial conditions when he introduced his
work to the public in a nineteen sixty three paper
titled Deterministic non periodic Flow. The term butterfly effect he

(02:58):
coined later in speeches about the topic. The paper was
rarely cited by other researchers, at least at first. Later on,
other scientists realized the importance of Lorenz's discovery. His insights
laid the foundation for a branch of mathematics known as
chaos theory, the idea of trying to predict the behavior
of systems that are inherently unpredictable. You can see instances

(03:22):
of the butterfly effect every day. The weather is just
one example. Climate change relatedly is another. For example, as
it turns out, warming climates are impacting appropriately enough species
of alpine butterflies in North America. We spoke by email
with Alessandro Philozola, a community ecologist and data scientist and

(03:43):
postdoctorate fellow at the University of Alberta. He said climate
change is expected to have some large impacts, such as
too hot for some species or too dry for others,
but there are nearly infinite amount of smaller indirect effects
that will also occur. In our research, we looked at
one of those indirect effects and saw how future climate

(04:04):
will slowly cause mismatch in spatial location of a butterfly
and its host plant. As a caterpillar, this butterfly only
feeds on this type of plant species, so any mismatching
range will cause a decline in the butterfly. He adds
that if we were to pause for a moment and
think of all of the other species in a food web,

(04:25):
suddenly there's the potential of many species being affected, not
just one butterfly, but everything that eats it or that
relies on the decay of its body for nutrients, and
everything that eats those animals and fungi and plants and
everything that's in competition with it for resources. That's the
butterfly effect in action on a large scale. When we

(04:46):
start to consider how one small change can quickly result
in a lot of unintended consequence. There's naturally cause for concern.
For example, limiting the construction of hydroelectric dams might reduce
certain types of environmental damage, but in eliminating this potential
source of clean energy, we tend to fall back on
fossil fuels that accelerate global warming, and biofuel subsidies meant

(05:11):
to reduce our dependence on fossil fuels have increased rainforest
destruction and freshwater waste, and have lead to increases in
food prices that have affected the poorest segments of the
human population. How can we possibly do much of anything
in our lives then, without fear of causing harm? Philo
Zola returns to the butterflies as an example. He said,

(05:33):
better understanding of indirect effects is probably one of the
most important steps in trying to mitigate those effects. More simply, though,
just keeping nature as close to its original state is
really the most important thing. Ecosystems are vastly complex, and
the loss of a single species might not have a
perceived effect, but it could have cascading effects on the

(05:54):
entire system. For another example, reintroducing wolves to yellow Stone
park where they had previously been hunted out of their
historical range, has wound up increasing beaver populations and increasing
the number of willow and aspen plants, and provided food
for birds, coyotes, and bears, among other benefits. Then we

(06:16):
have to consider how the butterfly effect can play into
our individual lives. With nearly eight billion humans on the planet,
can just one person make changes that echo around the earth?
Phila Zola says that he does wonder about the indirect
effects of his personal actions. He said, the items I buy,
the people I interact with, the things I say I

(06:37):
believe each can have their cascading effects that rippled through society.
That's why it's important to try and be a good
person to create a positive influence. One thing I also
think about is how these indirect effects are often not
as small and removed as I believe many would think.

(06:58):
Today's episode was written by an Than Chandler and produced
by Tyler Clang. For more on this and lots of
other small topics with big impacts, visit how stuff works
dot com. Brain Stuff is production of I Heart Radio.
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