Welcome to Meteorology Matters. Today we're looking
at something really quite strange, a real climate
puzzle. Imagine this, a huge part of the Atlantic
Ocean is a little cold. And it's actually getting
colder, even while the planet overall is hitting
record high temperatures. It does sound completely
counterintuitive, doesn't it? Like finding an
ice cube floating in a hot bath. Exactly. And
understanding this cold spot is, well, it turns
out it's pretty key to understanding the bigger
climate picture. So in this Meteorology Matters
podcast, we're going to explore these surprising
connections. Why is this happening? What does
it mean for our weather? And really, why should
you care about it? That's a great topic. For
years, this was a genuine scientific head -scratcher,
a real anomaly. But recent work, some really
intensive research has started to piece it together.
This cold blob, as people call it. It's a specific
spot in the sub -polar Atlantic south of Greenland.
And measurements show it's cooled maybe by up
to 0 .3 degrees Celsius over the last century
or so, while everywhere else is warming up. Right,
0 .3 Celsius or about half a degree Fahrenheit.
That's not tiny, especially when the waters right
next to it are warming. And like you said, there
was this debate for a while, wasn't there? Was
it just ocean circulation doing this or was the
atmosphere somehow involved too? Well, the latest
thinking, the newest research points pretty clearly
to both. It seems ocean and atmospheric processes
are. pretty much equally responsible. Okay, both.
And understanding that mix is vital because this
isn't just some local quirk. This cold patch
can actually disrupt things like the jet stream
and that affects storm tracks, you know, big
time. Okay, so let's break that down. The ocean
part. Yeah. That involves the AMOC, right? The
Atlantic Meridional Overturning Circulation.
That's the one. The AMOC is this absolutely enormous
system of ocean currents. Like a giant conveyor
belt moving water around the Atlantic. Precisely.
It brings warm, salty water up from the tropics
towards the north. Where it cools down. It cools,
gets denser because it's salty and cold, and
then it sinks, deep down. And then it flows back
south again, deep underwater. And this whole
circulation, this conveyor belt, is massively
important for climate, especially here in Europe
and North America? Hugely important. It helps
regulate temperatures, distributes heat. It's
a major climate driver. And the origin of this
cold blob... It's directly linked to a slowdown
in the AMOC. Ah, okay. So why is it slowing down?
The main culprit seems to be freshwater. Lots
of it. Melting ice from Greenland, mostly. This
freshwater pours into the North Atlantic and
it dilutes the salty ocean water. Making it less
salty and less dense. Exactly. Less dense water
doesn't sink as readily. So that sinking part
of the conveyor belt, the engine driving it,
it weakens. The whole system slows down. And
less heat gets transported north, leading to
that cooling south of Greenland. That's the mechanism.
And we have data going back over 100 years showing
this long -term weakening trend in the AMOC.
Plus, the climate models really back this up.
Only the models that simulate a weaker AMOC can
actually reproduce the cooling and the freshening,
the lower salinity that we've observed in that
specific region. OK, so that covers the ocean
side. But you said the atmosphere is equally
involved. How does a colder ocean surface affect
the air above it? Is it just, like, locally cooler
air? It's more than just cooling the air directly.
It's about moisture. Colder water means less
evaporation. Right. Less water turning into vapor.
And less water vapor in the atmosphere means,
well, water vapor is a greenhouse gas, isn't
it? It traps heat. Ah, I see. So less water vapor
means less trap heat locally. Precisely. You
get a drier... cooler atmosphere right above
that cold patch. And this drier, cooler air then
feeds back onto the ocean, helping to keep it
cool, maybe even making it a bit cooler still.
So it's feedback loop. The cold ocean makes the
air cooler and drier, which then helps keep the
ocean cold. Exactly. It amplifies and sort of
locks in the cold. It's like turning down the
local greenhouse effect just in that area. It
really shows just how tightly interwoven the
ocean and atmosphere are. It's such a delicate
balance. OK, so. Bringing this back, why should
someone listening right now, maybe miles away
from the Atlantic, why should they be concerned
about this cold blob? What are the real -world
impacts? Well, they're quite significant, potentially.
First, as I mentioned, messing with the AMOC
and creating this cold spot disrupts the jet
stream. That directly influences weather patterns,
where storms go, how much rain falls across North
America and Europe. Think extreme weather events.
Okay, so more unpredictable weather. Potentially,
yes. And then, if the MOC were to weaken drastically,
or in a worst -case scenario, collapse. That
could trigger a really sharp temperature drop,
especially across northern Europe. We're talking
major changes. Wow. OK. What else? There's sea
level rise. Changes that AMOC can actually affect
sea level heights, potentially making sea level
rise worse along the US East Coast. Really? How
does that work? It's complex, related to ocean
dynamics and how the currents pile up water.
But a weaker AMOC can allow coastal sea levels
to rise more on the western side of the Atlantic.
And of course, changing water temperature and
salinity has huge impacts on marine life. fish
stocks, ecosystems. They're all sensitive to
these shifts. So understanding all this helps
predict future climate changes better, especially
for places like Europe. Definitely. Improving
our climate models with this understanding is
crucial for forecasting, especially regionally.
You know, just when it sounds like we're heading
towards a potentially concerning slowdown...
There's this other twist, right? Something about
a possible backup system in the Arctic. Ah, yes.
That's a really interesting, fairly recent line
of research. The idea of some resilience in the
system. So what's happening there? Researchers
are observing something called Atlantification
in the Arctic Ocean. Atlantification, meaning
it's becoming more like the Atlantic. In a way,
yes. The Arctic is generally becoming warmer.
less ice covered, and warmer, saltier Atlantic
water is pushing further and further into the
Arctic Ocean each year. Where is this happening
most? We see it strongly in places like the Barents
Sea. That's actually expected to be the first
part of the Arctic to become ice free year round
and also north of Svalbard. OK, so the Arctic
is getting more Atlantic like. How does that
help the AMC, which relies on cold, dense water
sinking way further south? Well, the twist is
As this warmer Atlantic water interacts with
the Arctic conditions, and particularly as sea
ice forms in winter, the remaining water becomes
saltier and denser. And it turns out the Arctic,
through this atlantification process, might actually
be starting to produce more dense water than
it used to. Oh, interesting. So it's creating
dense water in a new place. Kind of. It seems
to be partly compensating for the slowdown in
dense water formation in the traditional areas,
like the Greenland and Norwegian seas. So like
a backup generator kicking in? That's one way
to think about it. It suggests the system might
have more resilience than we thought. But, and
it's a big but, we need more research. There
are still questions about whether the dense water
formed in the Arctic is... quite dense enough,
or if it can effectively replace the really deep,
dense water formation that historically happened
in the Nordic seas and powered the strongest
AMO circulation. Maybe some resilience, but the
jury's still out on how much. Precisely. It's
an active area of study. So wrapping this up,
it's clear this seemingly simple cold spot in
the Atlantic is tied into these huge complex
planetary systems, ocean currents, the atmosphere,
melting ice. It's a really powerful reminder
of how interconnected and frankly how delicately
balanced Earth's climate really is. Absolutely.
And our understanding is clearly still evolving,
which hopefully helps us anticipate what's coming.
makes you wonder, doesn't it? What else are we
going to discover that shifts our perspective
on how all this works? That's the fascinating
part. This research really drives home that even
with global warming as the big picture, these
regional variations, these anomalies like the
cold blob, offer vital clues. They show us the
nuances, the intricate ways the planet responds.
It really underscores, I think, why we need to
keep digging, keep asking questions, and be open
to complex answers in this changing world. Indeed.
Well, this Meteorology Matters podcast is a collaboration
with meteorologist Rob Jones. You can follow
Rob's work. He's on Instagram at Meteorologist.
That's M -E -T -E -O -R -O -L -O -G -I -S -T.
On TikTok, look for TV Meteorologist. And over
on YouTube, search for Rob Jones Hurricane. That's
Rob Jones Hurricane, all one word. And you'll
also find the Meteorology Matters podcast playlist
there. Thank you so much for joining us today
as we explored this piece of the Earth's amazing,
intricate climate puzzle.