Some housekeeping before we start. I'm going to update the blog every Monday and Thursday. Those posts will always be aimed to further the goal of the blog, simply explain the science of climate change. I will try not to do more or less, just exactly Monday and Thursday!
The secondary goal of the blog is to show people that Science and Math aren't terrifying, and are more like games and puzzles than water torture. So weekend posts which I will throw in sporadically will be much less focused and just discuss whatever I feel like. Hopefully these are interesting as well.
Anyway on to the post! This post has way more bananas in it than I ever intended.
In my opinion
there are two facts about Climate Change:
1- It is an incredibly complex problem with maybe millions of inputs and millions of outputs.
2- The climate was shifting drastically before any sentient being ever burned a fossil fuel
This second fact doesn't relieve us of our responsibility to discover what we are doing to the planet, but gives us a framework to base our results on. Just because your ship sinks in the roughest waters doesn't mean you stop trying to make your ships float all together...
Out of all of the factors that affect the climate there are three powerful ones we have no control over. All three have to do with how the earth makes its way around the sun. All three affect each other; constantly adding and subtracting energy from our climate. These effects are called the “Milankovitch cycles” and have been changing the climate of the planet for millions and millions of years without any help from us.
1- It is an incredibly complex problem with maybe millions of inputs and millions of outputs.
2- The climate was shifting drastically before any sentient being ever burned a fossil fuel
This second fact doesn't relieve us of our responsibility to discover what we are doing to the planet, but gives us a framework to base our results on. Just because your ship sinks in the roughest waters doesn't mean you stop trying to make your ships float all together...
Out of all of the factors that affect the climate there are three powerful ones we have no control over. All three have to do with how the earth makes its way around the sun. All three affect each other; constantly adding and subtracting energy from our climate. These effects are called the “Milankovitch cycles” and have been changing the climate of the planet for millions and millions of years without any help from us.
Orbital Shape
One of the
first things we learn in science class is that the earth goes around the
sun. They show us a picture with the sun
in the middle and 9 (now 8 I guess?) circles representing the order of the
planets from the sun. The earth doesn’t
go around the center of the sun however (take that Capernicus); two masses actually
rotate around their center of mass.
Imagine Center
of Mass as an average in space (The red square in the image above). If you
and I were the exact same size (first set of circles), our center of mass would be exactly halfway
between the two of us. If I was twice
the size of you our center of mass would be 1/3 of the way from me to you (second set of circles). If I were the sun and you were the earth I
would be ~ 330,000 times as massive as you and our center of mass would be
somewhere super close to my center, but not exactly my center. Therefore as you moved around me it wouldn’t
be exactly around my center, but we would both rotate slightly off my center
and make an ellipse (third set of circles)! Simultaneously all
of the other stuff in the universe is technically all revolving around each
other’s centers of mass. Since the sun
is so massive and close to the earth in comparison to everything else this will
only change the center of mass of the system slightly but this will change our
orbit constantly. It will become slightly
more, and slightly less elliptical. As
it becomes more elliptical parts of the orbit get closer to the sun obviously
warming up the earth, parts of the orbit are further from the sun – cooling the
earth.
A+ art! Also this picture represents a much more dramatic change than what actually happens
Axial Tilt
Another early
fact we learn about the planet is that the earth is “tilted” when compared to
its daily rotation. This is what makes
our seasons. When the top of the earth
is tilted towards the sun, it is both closer and receives more direct sun light causing Summer. The opposite is true for winter. It is like you leaning
closer and further from a fire. This
tilt is caused and also affected by all of the other things in the universe
constantly pulling on the earth. The
axis of the earth changes from ~21.5o to 24.5o. At a higher degree we see more drastic summers and winters (close/further and more direct light) than at a lower degree.
This process
takes 41,000 years to complete.
Mathematically Axial Tilt is expected to have the most effect on global
climate.
Axial Procession
Axial
procession gets the honor of the coolest name, most confusing effect to
explain, and least effect on the climate.
The effect is most easily described in the following two pictures:
Basically, as the earth spins on its axis it is not always pointing in the same
direction. Imagine you are playing dizzy
bats (Warning Dizzy Bats is Dangerous!); you place your head on the bat and
start spinning in a circle. The bat does
not stay perfectly perpendicular though because you are most likely intoxicated
and as you spin in the circles the top of the bat also travels in a
circle. This is basically what the earth
does. In conjunction with the changing orbital shape we now get different types
of “Summer”. When the earth is tilted directly at the sun (either North or South
Pole) and its orbit brings it closest to the sun we get the most direct light
possible, and are closest to the sun (marked as “Hottest Summer!”). The
opposite of all of that is also true for winter.
Axial Procession has never been the most dominant of the three cycles, it makes the effects of the previous two more or less drastic. A full procession takes 26,000 years.
Axial Procession has never been the most dominant of the three cycles, it makes the effects of the previous two more or less drastic. A full procession takes 26,000 years.
Issues with the Cycles
Prior to ~ 1 million years ago for well over 2 Million years the earth saw periods of glaciation ~ every 40,000 years. Periods of glaciation refer to times when the planet cools and glaciers grow with varying severity. This matches up nicely with the Axial Tilt cycle we talked about earlier. This is also a comfortable result for a physicists or mathematician, they expect Axial Tilt to have a major effect on the planets temperature and if glacial periods occur every 40,000 years we would seem to have identified the cause of climate change.
“Joe at the beginning of this blog you said
there are all those inputs into the climate how can we just ignore all of
them!?” We do approximations like this all the time
in math and physics; if one part of an equation is so dominant we can
approximate the other parts as 0.
Imagine you were a Banana Tycoon and lost 1 banana out of every 100 million you ship due to your very cheap shipping containers. You lost 1 million more due to moisture in your ships hulls. Depending on your profit margins you may ignore both problems, address the moisture issue and likely never address your cheap containers. We do the exact same thing in science and engineering all the time when we solve problems.
Imagine you were a Banana Tycoon and lost 1 banana out of every 100 million you ship due to your very cheap shipping containers. You lost 1 million more due to moisture in your ships hulls. Depending on your profit margins you may ignore both problems, address the moisture issue and likely never address your cheap containers. We do the exact same thing in science and engineering all the time when we solve problems.
The last
million years have thrown a wrench into this result however as periods of
glaciation have slowed to almost exactly 100,000 year cycles. While this cycle does line up with our Orbital Shape cycle it does not explain no longer following the Axial Tilt cycle. Also while the Orbital Shape cycle varies from 90,000
years to 120,000 years, the periods of glaciation have stayed stagnant at
100,000 years. This result is basically
the opposite of our Axial Tilt
result.
Imagine now you are a small town Banana stand owner who sells 100 bananas a day. You lose 1 banana a day to rot. If you stay a small town Banana stand owner you'll just ignore this rot forever. As you grow into a Banana mogul however your 1/100 becomes 10,000/1,000,000 a real issue! When a physicists or mathematicians has used an approximation but the formulas do not reflect reality they have to go through and consider all of the effects they approximated away. We have all seen videos of old bridges that have gone wild in the wind (if you haven’t (see ya later bridge). This is the result of someone not understanding that when they scale there small models the itty bitty terms they treated as 0 become huge, bridge shattering terms.
Imagine now you are a small town Banana stand owner who sells 100 bananas a day. You lose 1 banana a day to rot. If you stay a small town Banana stand owner you'll just ignore this rot forever. As you grow into a Banana mogul however your 1/100 becomes 10,000/1,000,000 a real issue! When a physicists or mathematicians has used an approximation but the formulas do not reflect reality they have to go through and consider all of the effects they approximated away. We have all seen videos of old bridges that have gone wild in the wind (if you haven’t (see ya later bridge). This is the result of someone not understanding that when they scale there small models the itty bitty terms they treated as 0 become huge, bridge shattering terms.
Basically the climate
It is because of
these shifts in glacial periods that we must consider all of the factors
affecting the climate. Things like fossil fuel emission, deforestation, urban sprawl which you reasonably could approximate as 0 with a 40,000 glacial period need to be looked at much closer.
No matter what we do the planet will get colder, it will get warmer, crops will thrive and struggle, but being able to accurately predict the result, as well as trend our effect on the planet, is invaluable. While it would be naïve to assume our total control of climate change – it is also incredibly naïve to not see the merit in studying it.
Next UP: Not Simply Science: The Inverse Square Law; Simply Climate: How we Measure the Climate of the Past
Image Credit:
No matter what we do the planet will get colder, it will get warmer, crops will thrive and struggle, but being able to accurately predict the result, as well as trend our effect on the planet, is invaluable. While it would be naïve to assume our total control of climate change – it is also incredibly naïve to not see the merit in studying it.
Next UP: Not Simply Science: The Inverse Square Law; Simply Climate: How we Measure the Climate of the Past
Image Credit:
http://empowereddollar.com/money-in-the-banana-stand/
https://upload.wikimedia.org/wikipedia/commons/4/43/Earth_precession.svg
https://upload.wikimedia.org/wikipedia/commons/6/68/Precession_and_seasons.svg
http://www.engineergirl.org/what_engineers_do/FunFacts/TacomaNarrows.aspx
https://upload.wikimedia.org/wikipedia/commons/4/43/Earth_precession.svg
https://upload.wikimedia.org/wikipedia/commons/6/68/Precession_and_seasons.svg
http://www.engineergirl.org/what_engineers_do/FunFacts/TacomaNarrows.aspx
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