lost in the fog of a cosmic storm floating on
whimsical wavelengths is the norm dancing through
the stars chasing spectrums of light riding the
waves that are just out It's solo time. Time
to tackle a particular topic that is difficult
to explore as an interview. And I have enough
background to go down this rabbit hole solo style.
Volcanoes and climate. But it's also the last
episode of the season. So let's do some cleanup.
Season two was amazing. Learning the craft. Growing
as a podcaster, learning search engine optimization,
social media, and getting better at science communication.
Not to mention building networks and the wonderful
guests. I've learned so much from them, and I
hope so that you have as well. They're the real
stars of the show. It is their work that is presented
here. I wanted an outlet when I started this
to explore science. Learn new things. and have
new avenues to view the natural world. To be
honest, this process of making whimsical wavelengths
is harder than I expected, but at the same time
rewarding. I even won an award for podcast of
the year in the science category from the American
Writing Awards and PopCom conference in Indianapolis
as well in science and technology. In the many
seasons to come, I hope to continue to grow,
learn new things, get better at making engaging
deep -dive science content, maybe add a few new
tools, and perhaps find new ways to grow the
podcast. That process involves you as the listener.
We've had one podcast episode that was completely
spawned by a suggestion. Perhaps there will be
many more. Once there's enough of a community
surrounding the show, perhaps an Ask Me Anything
episode? I don't know. The point is that the
show will continue to evolve. So there will be
three Encore episodes to get through the rest
of summer. And come mid -September, Season 3
will start. The current peg or date for that
is September 14th. Hopefully I can stick to that
as long as real life doesn't get too much in
the way. But I'm pretty sure we should be able
to make that September 14th to be that seasonal
tradition for whimsical wavelengths. Today, though,
I wanted to look at one of the many climate myths
that is thrown out there by those who don't like
data. People who want to believe something. is
false because it's against their ideology. Well,
actually, I'm not entirely sure why people believe
this, especially because it can be disproven.
In this episode, we'll do just that, and we'll
learn a little bit about volcanology and climate
along the way. The claim that we are dealing
with today, which we know is scientifically false,
volcanoes emit... more carbon dioxide than humans
do. That is a complete and utter false statement.
Volcanoes emit way less than what we humans do.
Now where to start with this? I guess I should
state a USGS scientist, Dr. Terry Gerlach, detailed
this in stark detail in his 2011 paper. And to
be frank, this episode follows much of his paper.
And we'll probably be returning to his conclusions
several times throughout the paper. If not explicitly,
but then implicitly. So, let's begin with volcanoes
emit gas. And that gas can basically fumigate
the area downwind. A caustic mix of gases. The
three most important volatiles or gases in magma
are water, carbon dioxide, and sulfur dioxide.
In that order. There are other trace gases like
hydrogen fluoride, hydrogen chloride, but they're
at much smaller amounts, and we'll leave those
aside, as they don't affect the whole calculation
of trying to figure out how much carbon dioxide
is degassed by volcanoes worldwide. So to look
at how we know volcanoes have a smaller footprint
or factor when it comes to greenhouse gases than
human emissions, we need to understand several
things. First, how much carbon dioxide should
be in the magma? How much magma is degassed each
year? And thirdly, how much do humans emit? So
let's start with one. How much carbon dioxide
should be in the magma? Well, how much gas in
total? Like, the total number of volatiles. The
logic goes, if we can estimate the amount of
gas in the magma, then all we need to do is figure
out how much degas is every year on average,
and we'll have a good estimate of the number.
There's a lot of nuance in all of this data and
numbers, which will hopefully become apparent.
A common theme in... the volcano episodes here
on Whimsical Wavelengths, is that magma or lava
is not a simple liquid. Today we will bypass
the rheology or how magma and lava flows and
moves to look more at the chemistry. Because
this is not like, say, water from the tap. There
are many different chemical constituencies in
magma, the biggest of which is... sulfur dioxide,
taking up just less than half, so 50%, all the
way up to 75 % of the weight of magma. Gases
or volatiles make up somewhere between 1 and
7 weight percent, depending on the environment.
And we'll kind of dive into that in just a minute
or two. So, how do we know that, you ask? Well...
This is the why I wanted to do this episode,
to explain how we get to the conclusion. It isn't
built in a vacuum or a black box. It's based
on a series of real -world discoveries and advancements
that were completely unrelated to climate change
or climate science. It really was all about the
volcanoes. For this first rung of the ladder
that gets us towards the final conclusion, let's
continue with the geochemistry of the rocks and
then... melt inclusion geochemistry. So we can
get whole rock geochemistry grinding up the rock
into a powder and then running it through an
x -ray fluorescent spectrometer. Basically, we
hit it with wavelengths. You can think of the
result here of what the magma chemistry would
be if the rock was melted. For volcanic rocks,
would it be the actual magma chemistry? The answer
is no. Without getting into the weeds about how
magmas change and evolve as they move towards
the surface, what is really missing is the volatiles.
The gas. Like a pop bottle that you shook. When
the magma gets close enough to the surface, it
is like the lid is unscrewed and gas is released.
Because the pressure dropped. The material after
an eruption has much less gas in it. It came
out of solution and was carried away in the wind.
I think I did a pretty good job back at the beginning
of this season, Season 2, Episode 1, when discussing
Messiah Volcano with this topic. So if you want
a deep dive with respect to volcanic behavior,
revisit that episode. Unfortunately, magma is
much more complicated than a bottle of soda.
Soda, we only need to worry about water, pressure,
and carbon dioxide. Magma has lots of different
chemical constituencies and volatiles, and it
changes. As far as volatiles or gas, they all
have different solubilities as well. So that's
the ability of a particular substance to stay
in solution inside a liquid. Sulfur dioxide,
for instance, comes out of solution quite late.
If you detect sulfur dioxide, you know magma
is close to the surface. Carbon dioxide, on the
other hand, is less soluble. Not too long ago,
we looked at carbon dioxide flux with Gaetano
in episode 18 for Kilauea and its deep magmatic
system. And in Kilauea, the carbon dioxide starts
to exolve and come out of solution around 35
kilometers beneath the Earth's surface. And that's
deep. For today, and this topic, showing humans
are releasing more carbon dioxide than volcanoes,
this is a bit of a wrinkle. It's a lot easier
to monitor sulfur dioxide degassing. It happens
when everything is quite close to the surface,
so carbon dioxide... We need to dig a little
bit more. Remember, I have already divided this
episode into three, and this first part is all
about how much carbon dioxide should be in the
magma. I actually should have phrased it, how
much is in the magma, and how much gets degassed.
So, to get that number, we need a time capsule.
We need to find magma before it ever had a chance
to pop the top, or... get out close to the surface
and lose its gas. In volcanology, we look for
what we call primitive magmas. I've already alluded
to this, sort of. As magma travels through the
crust and cools and changes, different crystals
form and change the concentration of what's left
in the melt. Basically, all magma that erupts
onto the surface has changed somewhat on its
journey. A primitive melt rises quickly from
the mantle without significant changes to its
chemistry. The reason why these primitive melts
are so valuable is we can use them to understand
the original chemistries of the magma. And for
this topic, we can get close to the original
concentrations of carbon dioxide because of melt
inclusions. Imagine a crystal, usually olive
ink, growing deep underground. As it grows, it
occasionally traps a tiny droplet of the surrounding
liquid magma inside its structure. Because that
olivine crystal is incredibly strong, it acts
like a microscopic pressure vesicle. It keeps
that little drop of magma under the same intense
pressure it felt many kilometers or miles below
the surface, preventing the volatiles like carbon
dioxide from escaping. But even these little
time capsules... Kind of a bubble problem. As
magma is erupted, it cools. The liquid inside
that little time capsule of a crystal shrinks
and a tiny vapor bubble forms. Because carbon
dioxide is so unhappy or incompatible or insoluble
in the liquid, almost all of it, sometimes up
to 90%, comes out of solution into that tiny
little bubble. And quite frankly, for a long
time, we were underestimating volcanic carbon
dioxide. that comes from these volcanoes because
we're only measuring the carbon dioxide in the
glass in the melt inclusion and ignoring the
bubble. Today we use Raman spectroscopy, basically
hitting that bubble with a laser, I mean wavelengths,
to measure the density or concentration of the
gas inside. By adding the gas in the bubble back
into the gas in the glass, we get a truer concentration,
original concentration of carbon dioxide. when
that magma was entrapped by the olivine crystal
it is important to note that this must still
be treated as a minimum as carbon dioxide could
have degassed before it was captured from the
melt one would think that primitive melts something
that can go from the mantle to the earth's surface
relatively quickly with very little changes are
rare so what happens when we can't find good
primitive melt inclusions. Well, now we have
to use different techniques, like the geochemical
buddy system. We look at the ratio of carbon
dioxide to elements that behave similarly but
don't turn into a gas, like niobium, Nb on the
periodic table, or barium. In the mantle, the
ratio of carbon dioxide to niobium is fairly
consistent and constant. Since niobium doesn't
degas when the pressure drops, we can measure
the niobium in an erupted rock and use that mantle
ratio to calculate exactly how much carbon dioxide
should have been there before the eruption started.
Okay, we can also do this with hydrogen -3 ratios
as well, but we need to really make sure we understand
something because the steps to back out carbon
Dioxide concentration of magma only really works
in your typical basaltic systems. Think mid -ocean
ridges like the Atlantic Ridge or the Nazca Ridge
or ocean island basalts, like hotspots, so Hawaii,
Galapagos Island, Piton Franais. And when we
apply these methods to primitive basaltic magmas
globally, we find mid -ocean ridge basalts come
up between 0 .05 and 0 .25%. carbon dioxide.
And for hot spots, like Hawaii, somewhere between
0 .5 and 1 .5 weight percent CO2. It might sound
like a lot, but when you do the math on how much
magma actually reaches the surface each year,
don't worry, we'll get there. But let's go back
to subduction zones, because subduction zones
are a lot trickier. First, getting primitive
melt inclusions are basically never found, because
the chemistry is so different due to the way
melting is caused. In mid -Atlantic ridge or
ocean island hot spots like Hawaii, it's primarily
due to depressurization. Either as you split
the rocks apart, you lower the pressure and you
cause melting, or in the case of a hot mantle
plume, not only do you have the increase of heat,
but you also are moving hot material up towards
the surface through the plume and depressurizing
and causing some melting. However, for... Subduction
zones, it's the addition of volatiles, namely
water. So, a quick refresher. Subduction is where
one ocean plate is pulled under another. The
subducting plate is carrying a lot of water,
locked up into the minerals as well as just into
sediments and the like. When the plate is plunged
beneath the other, it gets pushed into the hot
mantle below. It's heated up and put under incredible
amounts of pressure, the lithostatic pressure.
because of all that weight of the rock above
you. This causes the water to be released and
rise into the mantle above the subducting plate.
Adding water to the hot mantle reduces its melting
point and causes it to partially melt. The resulting
chemistry from this process is also different.
That is an important point. There will be material
in the subducting plate or slab that will leave
with the water and other volatiles. What? because
those elements are extremely soluble in the released
fluids or volatiles from the slab. One of the
knock -on effects of this is increasing the oxidation
of the melt. I'll throw out a term here as a
bookmark if you want to go further on your own.
Oxygen fugacity. The fluids change how the melt
behaves and what crystals or minerals are stable.
For our story here, we care about titanium oxide
or rutile. It is this mineral that gives niobium
a way out of the melt. It can substitute into
the crystal structure, meaning we cannot treat
it as a geochemical buddy to carbon dioxide like
we can for the basaltic systems. It can also
add carbon dioxide. See, the subducting slab
is carrying more than just water, as we are potentially
adding significant carbon dioxide from the slab
volatiles. So, we need to go back to the slab.
As volatiles are expelled, it carries with it
large ion lithophile elements like barium and
strontium. Well, yes, these are present in the
mantle as well. They're only in really quite
small quantities in comparison to the slab fluids.
The resulting melt here, though, from this process
of adding volatiles and melting the mantle is
then significantly enriched in these elements.
So you can treat the concentration of strontium
or... Barium has a proxy for the slab component
of the volatiles. I went back and forth about
the best way to explain this. The more simple
case is when the mantle melting due to depressurization
and heat. Nubidium and things like helium -3
ratios work. As described, we can fairly accurately
peg the primitive carbon dioxide and check it
via melt inclusions. This slab component of adding
volatiles and changing chemistry? I think I need
a two -step explanation. So I'm going to leave
the slab discussion behind for just a moment.
Let's look at the volatiles themselves. Active
volcanoes are degassing carbon dioxide and others
like sulfur. In fact, sulfur stays locked up
in the magma until it's quite close to surface.
The resulting gases are also easy to detect in
volcanic plumes using wavelengths. A little further
into this quick aside. Similar to what is done
in astronomy studying nebula and other planets
to observe what gases are at present, spectrums,
absorption lines. Each gas will absorb different
wavelengths, and if we know the original spectra
of the light source, we can back -calculate what
the material was in between. We volcanologists
use the same principle. We use a light source,
usually the sun, but sometimes we can use a lamp,
and we look at... parts of the spectrum that
are absorbed between whatever we're using to
measure and the light source. And typically,
we're looking at what spectrums were absorbed
by the volcanic plume to back out the concentration
of things like sulfur. And then integrate across
the whole plume, like say you're driving a car
or flying a helicopter underneath the plume looking
up into the sun, we can have a total emission
per unit time for sulfur. Okay, back on track.
Sulfur only degasses after the magma is quite
close to surface. We can get measurements from
the ground and from satellite -based instruments
on the total sulfur emission rates. Now, we can
play a game of ratios. Assuming one can find
a hot primary fumarole on the volcano, that is.
Because that hot primary fumarole, using it,
we can get a sample of the volatile breakdown.
of what's coming through the magma system at
the time. We use what is called a Gigenbach bottle.
Named after Werner Gigenbach who first introduced
them. The bottle essentially has a vacuum in
it using hoses that are shoved into the fumarole.
They have to be hoses that are going to withstand
that kind of temperature. The valve is opened
and the vacuum provides the force to suck up
the escaping gas from the fumarole. This gas
is sampled carefully to represent what is coming
out of the volcano. which can be taken back to
a lab and analyzed for its chemical constituents.
Now, even here there are some assumptions, like
the hydrothermal system has no interaction, the
degassing is linear, tapping only the magma body,
and probably a few others that I'm neglecting
to mention off the top of my head. There's also
other ways of doing this in situ using wavelengths
in a similar way to what we've already described,
but they have much higher air bars as you're
looking above the fumaroles or the vent, and
it's all mixing within the atmosphere instead
of being concentrated within the fumarole itself.
Okay, so we have a ratio of carbon dioxide and
sulfur. Based on this very hot, ideally primitive,
it's coming straight from deep within the Earth,
and... because of all that monitoring at the
earth's surface we have total sulfur so now we
can use a ratio to back out a total carbon dioxide
but wait there's still problems sulfur doesn't
fully degas from the melt after eruption some
stays behind and gets locked up in the volcanic
glass so the total sulfur measured via the emissions
isn't the total in the magma There's also other
processes that can cause sulfur to be left behind
near the bottom of the magma chamber. So the
air bars at this point are actually quite large.
Yes, we can correct or estimate the amount that
stays behind in the glass, in the rock, but those
deeper processes are really out of sight. We
don't really have a good way of measuring them
and figuring out just how much is being scrubbed
out of the system. So let's bring back. Our large
ion lipophile elements. Oh, and melt inclusions
too. To overcome these large bars that we have
encountered so far requires two things. And some
math and trend lines. First, measuring the barium
and lanthium a whole bunch of times across eruptive
products. Barium and lanthium elements, they're
non -volatile. And stay in the melt until the
very end. These ratios are locked in and shouldn't
change. And the interesting thing here to note
is that barium, as we've talked with strontium
above, comes from the slab. And lanthium does
not. It will not increase due to the volatiles.
It's coming from the mantle and not the slab.
So this means that increasing barium, or increasing
the ratio, means increasing the slab component.
It's really, really important. We're playing
a geochemical sleuthing game here. Now, all we
need is melt inclusions. Finding an olivine melt
inclusion that we can use for the official sulfur
concentration. In arc or subductive settings,
this is not easy. Many volcanoes in this setting
do not erupt lava with the right chemistry to
form olivine. They're too, quote -unquote, evolved.
which just means too much change from the primary
melt or the first melt produced in the mantle.
But in every arc, there are usually a few volcanoes
that erupt basalt, and these elusive olivines
with melt inclusions can be found. To name drop
a bit more, shoulders of giants, it was geochemists
like Terry Plank and Alessandro Iuppa that plotted
the surface gas ratios of carbon dioxide to sulfur
dioxide against the whole rock of barium and
lanthium ratios of global volcanoes. They observed
a striking, tight, linear correlation. The volcanoes
with the strongest slab signature in their rocks
constantly had the highest carbon dioxide to
sulfur ratios in their gas. The slab components
matter. So putting it into practice, this two
-step geochemical trick or empirical relationship
together. Step one, we take those rare primitive
olivine melt inclusions from the anchor volcanoes,
as we'll call them right here, and use them to
measure the true deep sulfur concentration of
the magmatic source before it hits the surface.
Step two, we pair that deep volatile data with
whole rock trace element chemistry specifically
the ratios of barium which is going to represent
the slab to lanthium which represents the mantle
to act as our geochemical slab meters by plotting
many of these values for an arc trend lines are
built with a robust trend line we can take the
ratio of barium and lanthium from any volcano
or eruption within a particular arc and use the
trend line to obtain the carbon dioxide total
to sulfur dioxide total ratio. Now we can use
the average sulfur still in the glass of erupted
products because sulfur doesn't completely degas.
So we can get that total sulfur that is being
degassed and match it to what we measure on the
Earth's surface. and therefore obtain a reasonable
value of the carbon dioxide budget for a particular
arc. Over the years, this data was collected
to understand volcanoes. Primitive mountain inclusions,
chemical ratios, empirical relationships, they
were developed to understand volcanoes and Earth
processes, not climate change. That was never
the goal, but once you have it, Now you can start
asking questions because it has a direct application
as an input for the atmosphere. It just becomes
abundantly clear. I don't want to get sidetracked
into looking at aerosols and sulfate and the
expected cooling that happens from explosive
volcanism. Perhaps one day I'll walk through
a super volcano and what an eruption would do
to climate as a solo episode. The point is volcanoes
can have large impacts on climate. We know looking
back through geologic time, the volcanic activity
was one variable changing long -term climate.
And obviously in very large eruptions, it will
have a punctuated short -term climate change
as well due to the sulfate. So we have our volatile
weight percents. So applying this analysis to
mid -ocean ridges and ocean island basalts, like
hotspots, like Hawaii, we get estimates of our
carbon dioxide concentration. And I'm going to
be giving it here is grams per kilogram of magma.
So at mid -ocean ridges, we have 0 .5 to 1 .5
grams per kilogram. We can have an extreme high
of about 2 .5, really, for mid -ocean ridges.
For ocean island basalts like Hawaii, we get
5 to 15 grams per kilogram. The extreme side
of this is 30 grams per kilogram. And arcs, 5
to 20 grams per kilogram. In the extreme, it
can be up as high as 40. Yay, numbers! Well,
that is the first part. All done. Now we're on
to part two. How much magma degasses each year?
So we have the concentrations. There's two different
games we can play here. We can calculate an average
per year eruptive flux, i .e. how much is on
average erupted per year in each geologic environment.
Or we can try estimating via measuring... sulfur
degassing flux and use ratios developed above.
Here on the podcast, though, it's easier to talk
and walk through the first one. So let's do that
and present values for sulfur estimates. For
some volcanoes, we have great constraints on
eruptive output due to how active they are. The
Hawaiian volcanoes, Etna, Masaya volcano as location
examples. When we start to deal with broader
arcs like the Cascades or the Andes, there are
areas that go thousands of years between eruptions.
So detailed mapping of the eruptive products
and averaging over the entire arc is the game
we need to play. For mid -ocean ridges, spreading
rates and averaging the required output for the
entire length is what we'll do. So let's take
the Cascades as the first example. It has one
to two eruptions per century, which works out
to 0 .001 to 0 .01 kilometers cubed per year
for the whole arc. Yeah, there's going to be
a lot of numbers. The point is, is that it's,
you know, quite a small percentage or quite a
small volume in the grand scheme of things. Expanding
this to a global scale, the above sea level volume
of subduction arc magmas is just 1 .8 to 4 cubic
kilometers per year. That's for the entire globe.
What about the underwater arc volcanism? Think
island arcs where the volcanoes are still below
the waves. Well, for our numbers, these eruptions
get fuzzier. We still only get additional half
to one cubic kilometer, though, even though the
air bars are slightly large. Using a maximum
volume here of five cubic kilometers, that's
a fair bit of magma, representing five Mount
St. Helens eruptions in 1980. What about the
gas? Going back to the high end of the estimates
above of 20 grams per kilogram. And let's just
keep it as grams per unit volume as it's much
easier to estimate. We get 53 ,000 grams per
meter cubed. Unit conversions arrives at 53 million
metric tons of carbon dioxide per cubic kilometer
of erupted material. So we have 265 million metric
tons of carbon dioxide for arc volcanoes. using
our high -end estimates for volatiles that last
part is important so far the numbers being used
here are near the maximum for volume and co2
concentration using minimum numbers drops that
value by a factor of 10. now ocean island basalts
best estimates based on the data is two cubic
kilometers going back to our carbon dioxide flux
and again choosing the maximum 15 grams per kilogram
of magma and again using the same unit conversions
arrives with 81 million metric tons of carbon
dioxide finally mid -ocean ridges where plates
are pulling apart this gets a bit problematic
first and foremost most of these eruptions occur
deep beneath the ocean CO2 erupted there doesn't
degas to the atmosphere. There are chemical reactions
and the like that will bind it earlier, but for
this exercise, we're just going to keep it simple.
Based on observations and models, ridges erupt
3 to 4 .5 cubic kilometers of magma. They intrude
or stuff magma beneath the crust at a rate of
18 to 21 cubic kilometers a year. Adding it together
and taking the maximum and ignoring the fact
that essentially zero would directly interact
with the atmosphere, we get 26 cubic kilometers
of magma being erupted or emplaced. Again, going
back to the concentration for the mid -ocean
ridges, we get 1 .5 grams per kilogram. And then
running the same unit conversions arrives at
105 million metric tons of carbon dioxide. Adding
all of these together. 105, 81, and 265. For
the mid -ocean ridges, the ocean island basalts,
and the arcs across all of the world, we get
a grand total of 451 .3 million metric tons of
carbon dioxide degassed per year. So given, throughout
this, I've chosen values near the max every single
time. The real number will be smaller. In fact,
let's look at those published values that take
a longer view, breaking it down more granularly
instead of just taking the values near max like
I did here, doing a lot more estimates, if you
will. The maximum published value is 440 million
metric tons. The minimum is 130 million. The
value from the paper I introduced at the very
beginning, the 2011 seminal paper by USGS scientist
Dr. Terry Gerlach, arrived at 260. metric tons
as the best value. So my more simple method based
on estimates of global magma flux is very close.
Not super rigorous. I chose to do something different
than just reproduce Dr. Garalex to show that
the same conclusion can be arrived at using different
measurements. This is important. This is how
we test science. This isn't just... I am taking
somebody else's numbers and reproducing the exact
same thing in the paper. Oh no, I took numbers
that represent the globe instead of what Dr.
Terry Gerlach did, which was a bit more granular
and a lot more accurate, given the numbers that
he had at the time that he published. I tested
the same hypothesis and got basically the same
result. So we have the number 451 metric. Million
metric tons. And we're going to keep going with
this number. A true maximum. So, step one and
step two are done. We have a value for the volcanoes
of the world. Now for the human emissions part.
The final part. We don't need to play a game
of melt inclusions and eruptive output. The methodology
is very different. I will go into some of it
here, but... It's all published by organizations
like the Intergovernmental Panel on Climate Change,
IPCC, the International Energy Agency, IEA, and
the Global Carbon Project. If you have in -depth
questions, send the show an email, or better
yet, jump into the source material. You don't
have to just take my word for it. That's why
we publish things as scientists. That's why if
you... Know enough and willing to take the time,
you can go derive it all from the first principles
and follow the same rubric that is set out in
these publications. So let's start with fossil
fuel. The organizations that I just mentioned
above estimate fossil fuel numbers from values
that are produced independently by legally binding
international trade data, customs ledgers and
national energy taxation registers. It's not
scientists trying to estimate something through
proxies. These numbers are accurate because of
the requirements of modern reporting. Scientists
just get to use the data. So using the type of
fuel being sold and what it will produce when
burned, we can account for nearly 90 % of human
emissions. There are, of course, non -fossil
fuel sources as well for carbon dioxide, and
those are a bit harder to pin down. Generally,
we're talking about cement. If this is a surprise,
it's because you don't know how it's made. We
take limestone, calcium carbon oxygen 3, that's
what limestone is, and heat it to get calcium
oxide. What's missing when you get calcium oxide
from CaCO3? Carbon dioxide. It also takes a whole
lot of heat to get limestone to break down like
that. The heat? Yeah, often we almost always
use fossil fuels. I don't want to get into the
weeds here, but we're looking at about 8 % of
human emissions. New technology could bring that
number way down. Building materials move slow
because of regulations. Regulations are very,
very important. I live in an earthquake zone.
I wish I could speed up the testing and adoption
of these technologies, though. The last bucket
of human emissions is land use, deforestation,
soil degradation. We can model this and make
measurements, but the data here is a bit fuzzy.
Then again, it is a very small factor than the
first two. We're looking around, you know, somewhere
in the realm of 2%. Breaking down. Fossil fuels
emissions clock in around 33 .3 billion metric
tons, leaving all the rest at 4 .7 billion metric
tons of carbon dioxide. Remember the volcanoes,
our number? 451 million metric tons, or if we
want to make it the same so we can compare it,
we're looking at 0 .45 billion tons. Just 1 .2
% of what we humans produce. So where does that
leave us? We've gone from the microscope pressure
vessel of an olivine crystal to the massive plate
tectonic reality of subduction zones. We've looked
at the bubble problem, played the geochemical
buddy system, and mapped out all the trend lines
of global arcs. After all that math, all the
sifting through the gas ratios, the trace elements,
we arrive at the bottom line. Yeah, volcanoes
emit carbon dioxide. Sure. They are, you could
argue, the heartbeat of the planet's natural
degassing. They are definitely one knob in the
whole climate system that the Earth just does
without us. But when you look at the total global
budget, the contribution from human industrial
activity is just different. It's... orders of
magnitude larger. The idea that volcanoes are
out emitting humans just doesn't hold up. The
data doesn't support it. I hate to say that it's
a myth because there's not much truth to it other
than volcanoes do emit carbon dioxide. And I
don't really understand the reaching for straws
to protect a viewpoint that falls apart when
we just look at the data. I hope this episode
gave you a bit of a window into how we actually
know what we know. Science isn't a black box
or a magical guess. So often it's a painstaking
process of cross -referencing different things
like bubbles, isotopes, and ratios to build a
clearer picture of reality. It's messy. It's
full of error bars. And sometimes it takes a
decade just to get one measurement right. But
it's how we move from I think to we know. So...
We know that humans emit way more carbon dioxide
than volcanoes. Okay, so this wraps up season
two of Whimsical Wavelengths, a science podcast.
And as I've already mentioned, it's been a wild
ride. I hope you've enjoyed peeling back the
curtain on how we make science as much as I have
for this final episode. To reiterate, I'm taking
a break for the rest of summer, planning to be
back on September 14th. Encore editions will
fill the gap to keep the feed fresh. It's also
a time to re -listen to some of my favorites
in the back catalog. So hopefully life doesn't
throw a wrench into everything I've planned for
the start of season three. And if it does, I'll
do my best to communicate about it should it
be delayed. Remember, leave a rating and a review
in your podcast app. Tell a friend about it.
This is literally the best way to... Spread whimsical
wavelengths and get it into other people's ears.
So much is planned for season three. Well, I'm
Dr. Jeffrey Zirk. I'm signing out. And I should
be back in your feeds with new episodes starting
September 14th. We have stories painting the
sky Swaying to rhythms as the galaxies fly by
J.