If you live in the Midwestern United States,
you might have noticed last week was
really cold.
Like, colder than some parts of Mars cold.
Chicago, for example, dropped to a low of
around minus 30 degrees Celsius
and with the wind chill, it felt as low as minus 50.
Schools were closed, postal services were suspended,
flights were cancelled.
It got so bad that dozens of people died
and many more lost toes and fingers to frostbite.
Now, with all that cold, some people
[not naming names here]
have argued that this winter
is evidence against global climate change.
Well, we’re here to tell you that is, obviously
just a bunch of hot air… or cold air or
whatever I don't care anymore...
The point is...there’s actually growing evidence
that a warming Arctic means colder winters.
Now, first things first.
Climate is not the same as weather.
Weather is what’s happening in the atmosphere
over a short period of time, while climate
is long term patterns in weather.
So just because it’s particularly hot or cold
one week doesn’t necessarily mean that
the climate is or isn’t changing over years or decades.
But long term changes in the atmosphere
can lead to more fluctuations in weather or extreme
weather events like what we saw
in the last couple weeks.
To understand why, you have to understand
what actually caused the sudden deep freeze.
You’ve probably heard the term
polar vortex being thrown around.
That’s a large area of low pressure
and cold air that hangs out
near one of the Earth’s poles.
There are actually two polar vortexes—one at each pole.
But the one in the North is the one that everyone
is talking about because it's the one that
Chicago can sometimes get enveloped by.
It’s usually kept in place by the polar jet stream—
a fast moving river of air flowing
in a counterclockwise direction
high above the earth’s surface.
When the jet stream slows down—
like it often does in winter—
it becomes weaker and wobblier,
and that can let the polar vortex
poke down into parts of the northern hemisphere.
As frosty air moves southward,
warm air from the equator moves northward.
And that means some areas freeze their tuchuses off,
while others are sweltering.
Sled dog races, for example,
had to be cancelled in Alaska
because it was too warm.
And the Southeastern US has been
dealing with a heatwave.
This push and pull of air leading to
extreme winter weather
isn’t a new thing.
In fact, the term polar vortex is
thought to have first be coined in 1853.
What is unusual is that these vortex-driven bouts
of extreme weather are happening more
often and lasting longer.
And rather than being proof positive that
global warming isn’t a thing,
that’s actually entirely consistent
with our understanding
of a changing climate.
Climate models predict that if the Arctic gets warmer,
there will be less of a temperature difference
between the air there and the air in mid-latitude regions
those between the equator and the poles.
That temperature contrast is part of what
fuels the winds,
so less of a difference would
mean slower winds high up in the atmosphere.
And slower winds make the polar vortex
less stable and the jetstream wavy-er,
so this kind of extreme winter weather
would be more likely.
It also means such weather events
would hang around longer, since the cold air isn’t
shoved back up North again as quickly.
And all that is exactly what we’ve seen happen.
The Intergovernmental Panel on Climate Change reports
that the Arctic is warming faster
than anywhere else on the planet
because of arctic amplification.
Basically, when sea ice melts, it leaves larger patches of
dark water that absorb sunlight
better than the ice sheets, causing further warming.
And a 2015 paper published in Science
showed that the speed of winds in the polar vortex
have decreased by 4 to 6 percent in the past 35 years
and the kinetic energy of those
winds has gone down by 8 to 15 percent.
This year, daily temperatures in the Arctic have been
up to 20 degrees higher than average.
And that undoubtedly made the vortex
even more likely to move southward.
Also, we can see evidence for climate change
all over the globe right now.
While there were two record lows in January—
both in Illinois—there were 35 record highs,
mostly in Australia.
Australia’s average temperature exceeded
30 degrees last month.
And such record-setting isn’t just happening this year.
If you look back over the past decade,
there have been a lot of records set, and a lot
more record-setting hot days than cold ones,
which is a pretty strong hint that our planet
is warming overall.
And I'd just like to point out that the US,
though we think of it as very big and important
is only around two percent of the earth's surface.
So no, a lot of ice and snow in one part
of this one country does not refute climate change.
In fact, this is kinda exactly what models
predicted would happen.
And those models suggest there’s a lot more in store.
A 2016 paper in the journal Nature Climate Change
found that the vortex has been getting
weaker and shifting eastward towards Eurasia
since the 1980s.
That means in the future, it’ll will likely dip down
over the East Coast more often—
and Europe, as well, is more likely to be hit by
arctic-like blasts.
But how often these extreme weather events
happen, or how long they will last in the
future, is of course still uncertain.
Weather is really hard to predict,
and we need more data on just how climate change
impacts the vortex and
other features of our atmosphere.
Still, it’s probably pretty safe to say
we haven’t seen the last really bleak winter—
or the last really scorching summer.
Thanks for watching this episode of SciShow News!
Before we go, we wanted to let you know
that we’ve added some fun perks for channel members,
including a way for members to submit
quick questions we might answer in videos!
To become a channel member,
just click the “Join” button below this video
or on our channel page,
and select which level you’d like to be part of.
All members get badges that show up next to your name
in comments and live chat,
as well as sweet custom emojis like these emojis.
You’ll also get a monthly behind-the-scenes photo
featuring some of our shenanigans we get up
to around here, and access to our QQ inbox.
This is a private form we will share with you,
and you can submit your quick questions there.
We’ll search this inbox for questions
each month, and if there’s a good one,
we’ll make a QQ video about it!
Higher-level members will get a monthly science fact
that we’ll post in the community tab.
These are fun graphics featuring very cool science facts,
provided in multiple sizes so you can
use them as backgrounds on your devices
and share the knowledge.
And finally, you can be a science ambassador.
Science ambassadors are credited as
cosponsors of the channel in the end screen credits of
our videos, because you are awesome
and we want to recognize what a huge contribution
you’re making to science education.
Whatever level you choose,
we really appreciate your support.
And of coursre if you can’t be a channel member right now,
that is absolutely fine,
and we’re all so very happy to have you watching SciShow
and getting smarter with us.
{♪OUTRO}