if you've been following the channel since the early days
you may remember me talking about a natural phenomenon called the latent heat of fusion
essentially it means in order to warm something up enough to change from one state to another
like changing these ice cubes from solid ice to liquid water
you have to shove in quite a lot of extra energy to convince the molecules to start jiggling around
in a more liquidy kind of a way so as these ice cubes take in energy from their surroundings
they warm up towards zero degrees celsius which is the freezing point but they're still solid ice to
make them change from solid ice to liquid water still at zero degrees celsius you have to put in
an extra 334 joules of energy for every gram of ice and that extra energy is what they call the
latent heat of fusion but here's the thing once you've done that and you've got liquid water at
zero degrees celsius if you put in another 334 joules of energy for every gram you'll
heat that water up from zero degrees celsius to 79 degrees celsius which is basically scalding
water so if we say this glass of water represents the arctic ocean and these ice cubes represent
arctic sea ice and this spotlight represents a heat source you know like the sun then you can
start to see why the climate scientists are suggesting we might have a bit of a problem
hello and welcome to just have a think now just for clarity i don't think the scientists
are suggesting that the arctic ocean is going to suddenly heat up to 79 degrees celsius but
then again you don't need anything like that kind of warming in a body of water
as big as Canada Alaska and Greenland combined to cause a pretty significant change to the entire
global atmospheric temperature what the scientists are very sure about is that the metaphorical spark
that lit the fire of global warming over the course of the last 150 years or so
it's a rapid increase in the concentration of carbon dioxide in the planet's atmosphere and that
increase is down to us humans now our planet has warmed up and cooled down loads of times over the
vast geological time scales going back millions of years that's why we get ice ages and interglacial
periods which is what we're in right now and it's absolutely true to say that carbon dioxide hasn't
always been the initial cause of the warming in many cases the graph shows us that warming started
before CO2 concentrations began to increase but in every case when the CO2 levels did start going
up they amplified the heating by setting up a feedback loop a bit like this microphone
sound goes in here passes through an amplifier and comes out of there but if i was to put this
microphone next to that speaker then the sound going in here would come straight back out of
there effectively doubling the noise going in here then twice the noise is coming out of there
and going in here so now you've got four times the noise and so on and so on and very quickly
you get that telltale feedback screech that the metal heads love so much our planet's been in
an interglacial period for about 11 000 years now during which time the overall global temperature
has never varied by more than about half a degree celsius above or below the long term
average and it's that remarkable climate stability that's allowed human civilization to flourish on
almost every available land mass right now the earth should be starting to cool down towards
the next glacial period and it would be too if it wasn't for those pesky humans the carbon dioxide
we've pumped into the atmosphere since the start of the industrial revolution is now leading the
warming of our atmosphere rather than following it like it has done on so many occasions in the past
and that means just like the feedback loop this system produces with noise we humans have
now sparked off a heat feedback loop up in the arctic which is impacting all sorts of variables
up there causing what the scientists refer to as arctic amplification here's what's going on
the industrial revolution gets into full swing towards the end of the 19th century
industrial societies burn oil coal and gas for fuel releasing hundreds of billions of tons of
carbon dioxide into the atmosphere over the course of the 20th century during that time we also clear
country-sized areas of forestry land to provide grazing pasture for industrial-scale livestock
farming and agricultural space for cereal crops all of which removes trees and plants that
suck up carbon dioxide and breathe out oxygen so towards the end of the 20th century the global
atmosphere starts to warm a little bit and our oceans start to warm up too research published
by the U.S National Academy of Sciences in 2019 found that the oceans have absorbed as much as 90
percent of the extra heat caused by CO2 emissions since 1870. according to this Forbes article
that's about a thousand times more energy than the global population uses each year the warming seas
cause an increase in the amount of melting ice up in the arctic sea and as we saw earlier with
our glass of ice water once the energy of the sun hits liquid water it heats it up pretty quickly
not only that but when there's ice covering the water its bright white surface reflects much of
the sun's energy back out into space that's the albedo effect that climate scientists talk about
so now you've got less reflection and more absorption of energy and as the channels
between the arctic ocean and the pacific and atlantic oceans on either side start to lose
their permanent plugs of ice the warm waters of those two vast oceans start to infiltrate the
arctic ocean and warm up the water even more some of that extra warmth is picked up from the water
by the prevailing arctic winds which increases the local atmospheric temperature then things
start getting a bit funky the warmer air causes the huge ice sheet sitting on top of greenland
to start melting faster that means more exposed land to absorb heat and less ice to reflect it
a similar thing starts to happen over in Siberia and on the East Siberian Arctic Shelf which sits
below a very shallow layer of arctic water barely 50 meters or so deep all these landmasses are made
up of large amounts of permafrost or permanently frozen earth containing organic material from
plants and animals that got buried and compressed over geological time periods as the permafrost
thaws out all the tiny microorganisms in the soil start feeding on organic matter and as they do
that they release enormous quantities of methane which is a greenhouse gas many times more powerful
than carbon dioxide so that adds another dollop of warming to the arctic atmosphere
on the 21st of June this year the town of Koyansk in Siberia which sits even further
north than Fairbanks in Alaska hit 38 degrees celsius or just over 100 degrees fahrenheit
that's not normal and those freaky temperatures are causing wildfires that are not just burning
trees and plants but also huge swathes of peatland which is extremely rich in carbon so more CO2 goes
up in smoke and the mercury rises still further all that arctic warming starts doing strange
things to the jet stream we've looked at the jet stream in detail in a previous video and you can
click up there to jump back to that one but in basic terms as the temperature difference between
the middle of the planet and the top of the planet gets smaller so the jet stream starts to get
slower and more wavy the upward waves drag even more warm air up from the middle of the planet
and the downward waves drag cold air away from the arctic all these feedbacks mean the arctic
isn't just warming up it's warming up as much as three times faster than anywhere else on earth and
that impacts all of us the polar regions act like gigantic thermal regulators for the entire planet
which is one of the reasons our atmospheric temperatures have remained so stable since the
last ice age and we humans have been able to build the civilizations and societies we live in today
and you can see from our feedback loop the arctic sea ice is a major factor in the climate stability
of the northern latitudes so tracking the ebb and flow of sea ice from its winter maximum in
march to its summer minimum in September has been a major feature of arctic research for
nearly 50 years in 2012 arctic sea ice reached its lowest summertime minimum surface area on record
at just 3.4 million square kilometers in 2019 we hit the second lowest extent on record
statistically speaking a summertime sea ice extent of less than one million square kilometers is
regarded as effectively an ice-free arctic ocean that's never happened in modern human history but
if it did then so much solar heat energy would be absorbed into the water that it's likely the ocean
would be ice free again the following summer and every summer from then on and as each subsequent
year went by the length of time that the ocean stayed ice-free would get longer and longer
until eventually there'd be no significant level of ice in the water at any time during any season
including winter so what's the state of play in 2020 well it's there again i'm afraid at the time
of filming this program on the 10th of September 2020 arctic sea ice had dropped to just under 3.8
million square kilometers very close to the 2012 record but there's a big difference between the
ice of 2012 and the ice of 2020 these are charts produced by the United States navy using upward
looking sonar from their fleet of submarines those submarines have to surface from time to
time so it's in their interest to know exactly how thick the ice is above them the key at the bottom
of the screen indicates ice thickness from zero to five meters if we zoom in on the 2012 chart
you can see that the coastal ice is all about four or five meters thick and even out in the middle of
the ocean there's still a good deal of multi-year ice more than two or three meters thick contrast
that with a zoom in on the 2020 chart all that multi-year ice has almost completely disappeared
leaving little more than 30 centimeters of slush it's covering a similar area but
it's nothing like the same kind of ice that was there only eight years earlier latest estimates
are that we may see an ice reality by 2035 but some researchers think it could be sooner than
that arguing that a covering of ice as thin and vulnerable as the one we're witnessing this year
could easily be smashed up and dissipated by a single violent arctic storm something that's
not unusual in that part of the world a raft of new research papers and articles were published
during the summer of 2020 pointing to a worse than expected acceleration of all these feedback
loops and tipping points including the faster than expected melting of the greenland ice sheet itself
which not only contributes to increasing arctic temperatures but also to global sea level rises
the general consensus of scientific opinion is that it's very unlikely we can now reverse the
process of climate change we're about 30 years too late for that but there's still plenty we
can do to slow it down and mitigate some of the worst effects that it'll bring that action starts
with our global leaders of course at the COP 26 climate conference to be held in Glasgow in 2021
all participating countries are legally obliged to present their updated and vastly improved
nationally determined contributions towards a rapid reduction in global greenhouse gas emissions
it remains to be seen whether those reworked numbers will achieve the target of limiting
global atmospheric temperatures to a maximum of 2 degrees above pre-industrial levels but one thing
is for sure nature doesn't care about viruses or economic shutdowns or political point scoring so
while those global leaders are preoccupied with a self-absorbed introspection our atmosphere
continues to get warmer and wetter and our planet continues to get less and less hospitable
to the way our societies are organized today no doubt you've got strong opinions on this
one so feel free to dive down to the comments section below and leave your thoughts there
now on a completely different tag before I go I want to let you know about a couple of
significant developments here at the Just Have a Think channel the first is the long-awaited
website that many of you long-term supporters will have heard me going on about for over
a year now well it's finally seen the light of day and you can visit it at www.justhavathink.com it's
a pretty straightforward site no floating parallax backgrounds or 3D virtual reality experiences
and it won't wake you up in the morning with a nice cup of tea or anything but it serves as an
online signpost to all of the channel's videos and it will also be where I post the transcripts
of each video which is something that a lot of you have asked for so that you can translate the
programs more easily into your own language in time it'll also become a blog post for me to talk
about more wide ranging issues that don't always make it into the main videos the second exciting
development is an exclusive Just Have a Think app that you can download to your phone or tablet I've
teamed up with a company called Bubblr who already operates a news aggregator app called Newsmine
as many of you know I don't do paid sponsorships or endorsements of this channel so no money has
changed hands in either direction on this project what I really like about the app is that you don't
have to register any of your information to use it so Bubblr don't exploit your data in any way
they also don't run ads on the app itself which is entirely in keeping with my ad free approach
to the channel videos so what you'll get is a completely free to use platform
from where you can jump directly to the Just Have a Think videos each week plus
news articles from thousands of sources around the world on climate and sustainable technology
categories that I've specifically chosen for the app you can also add your own categories
and you can turn notifications on and off for each category too so you only get notified
about the subjects that you're interested in it's simply called Just Have a Think and it's available
from the app store or google play i'll also leave clickable links in the description section below
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very much for watching have a great week and remember to just have a think see you next week
you