Oxygen is a gas that most animal and insect life on earth needs to survive.
Without it, we would suffocate.
But what if, lets say, the oxygen levels in the atmosphere decreased by 50 percent?
How would that affect life on earth as we know it?
That’s the question we’re asking right now on life’s biggest questions.
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Now that that’s settled, lets get into this question.
Can you imagine an earth without oxygen?
Well, the fact is, there was no free oxygen in earths atmosphere for the first couple
billion years of its existence.
Photosynthetic prokaryotic organisms began producing oxygen as a waste product and contributed
to the gradual build up of free oxygen in the atmosphere.
Then, there was the Great Oxygenation event.
Around 2.4 billion years ago, earths atmosphere and the shallow ocean experienced a rise in
oxygen.
No one knows exactly what caused this event, all we know is that from this point onward,
o2 started to accumulate in earths atmosphere and it changed a weakly reducing atmosphere
to an oxidizing atmosphere.
And many scientists cite this as a possible reason for large scale evolutionary phenomenon;s.
Over the course of history, the amount of oxygen in earths atmosphere has changed many
times.
During the Carboniferous period, 300 million years ago, the earths atmosphere contained
35 percent oxygen, and this likely was the reason why insects and amphibians were so
large at the time.
And by large I mean yuge.
Amphibious vertebrates were up to 20 feet in length.
Amphibians breathe through their skin, and in doing so they can take in far more oxygen
and grow to much larger sizes.
So by looking at what happened to the earth and its life forms when there was a lot of
oxygen, the exact opposite would be true if it had far less.
The current concentration of oxygen in earths atmosphere is between 16 to 21 percent, and
the rest is nitrogen, around 78 percent.
So decreasing it by half would mean that the earths atmosphere would be made up of 8 to
11 percent.
That’s not a whole lot.
We can also look at places on earth with far less oxygen, and how that affects humans.
Places at higher altitudes like mount Everest, where climbers need oxygen tanks to reach
high altitudes..
Ever been to macchu pichu in peru?
When you’re travelling to places like maccu picchu, tourists are warned about something
called altitude sickness.
Most people don’t have a problem ascending to sea levels of 2400 meters, but beyond this
height, changes in oxygen and pressure start to affect human physiology.
A few hours after arriving in cusco peru, you will notice the thinness of air, and you
will be out of breath after walking short distances.
Human bodies do adjust to lower oxygen.
Your red blood cell count will increase, your breathing will become faster and deeper even
when you’re resting.
From this information, we can assume that If the atmosphere even consisted of even 15
percent oxygen instead of 21%, humans would have a lot of difficulty breathing.
10 percent oxygen in the atmosphere is the minimum concentration for maintaining human
life on earth, and even with 10 percent oxygen in the atmosphere, most people would not survive,
especially not long term.
Larger animals that require more oxygen would likely die off, and smaller animals that require
less oxygen would flourish because of that.
There have also been studies done that suggest that the amount of oxygen in the atmosphere
affects the climate.
Oxygen actually affects how much sunlight reaches the ground.
Reducing oxygen levels thins out the atmosphere results in more sunlight reaching earths surface.
More sunlight means hotter temperatures and more water would evaporate, and that would
increase humidity and more humidity means more precipitation.
Needless to say, the earth would be a very hot, rainy, humid place with less oxygen.
It would also depend how quickly our atmosphere lost oxygen.
If it were to suddenly drop by half—that would cause significantly more damage than
if the oxygen in our atmosphere decreased over time.
A gradual decrease would somewhat permit some time for humans and other wildlife to adapt.
It should be noted that If the oxygen on earth decreased by half, that would mean something
else would have to replace that oxygen.
Something like carbon dioxide or methane gas.
If carbon dioxide replaced oxygen, then plant life very well could survive.
And without animals to consume that plant life, it would likely flourish.
There were many life forms on earth that existed without oxygen for millions of years.
That life then started to use the CO2 in the atmosphere, expel oxygen, and then other oxygen
breathing life forms would start to pop up again.
Removing half the oxygen in the atmosphere would cause mass extinction, but eventually,
life would begin again.
But if the oxygen in our atmosphere was replaced with something toxic like methane gas, life
forms, including plant life, would have a lot harder of a time surviving.
The scary thing is, the overall level of oxygen in the atmosphere is decreasing.
According to a study published in the journal science by Princeton university’s professor
Daniel stopler, oxygen levels have decreased by o.7 percent over the last 800 thousand
years, and it keeps declining.
Scientists don’t know why this could be happening, it could be a variety of factors.
an increase to erosion rates is one hypothesis.
The global cooling that’s taken past over the last 56 million years is another.
But the drop in o2 rates is happening very slowly, tens of parts per million per year,
which is far too slow to affect climate for the organisms who call earth their home.
In another million years however, the earth might look very different.
Well there you have it, thanks for making it all the way until the end of the video,
but we’re not quite done yet.
Lets look at some of your questions and comments from my last video on this channel, What if
SCP 3199 was real?
Raoizai red fox – what if humans could spit acid.
I think that would be fun!
Just me?
Kujamon – can you stop with these scp videos.
Sure, As soon as you stop clicking on them Darth Vetega – what if all the psycopaths
and narcissists in the world suddenly died.
I would assume there would be far less people.
Everyone’s a narcissist these days.