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What If #001: What if the Earth’s oxygen level doubled?

Team StoryWeavers|August 24, 2020, 07:54 IST| 11

Presenting a new series ‘What If?’ where you, the students, get to ask us your questions. It can be anything in the whole wide world but there’s just one condition: it should start with ‘What if?’ We’ll pick the most intriguing questions and feature it along with an illustrated explanation on The Learning Tree Blog. 

To ask your question, fill-up the form here:

Submit a ‘What If’ question

The first question in the What If? series comes to us from 11-year-old Manav Variar of Bengaluru. He asks:

What if the Earth’s oxygen level doubled?

The Earth’s atmosphere is made up of about 21% oxygen. Most of the air we breathe is actually Nitrogen – around 78%.

The Earth's atmosphere contains about 21% oxygen and 78% nitrogen

The thing about oxygen is that not only is it an essential gas for life as we know it to survive, but it is also the gas that facilitates all forms of burning and combustion. So would your birthday candle glow twice as brightly if the Earth’s oxygen was increased to 42%? Maybe. But there are bigger implications here!


With double the oxygen levels, your birthday candle would burn twice as brightly

Our human lungs have adapted perfectly to our current atmospheric setting. Just because oxygen is essential for respiration, it doesn’t mean too much of it is an improvement. Our bodies and indeed all life forms on Earth are finely tuned to the 21% Oxygen supply in the air. But it wasn’t always like this.

Scientists have discovered that around 300 million years ago, during prehistoric times oxygen levels were as high as 30%. During that time, insects were much, much larger! This means spiders were the size of eagles. And lizards were the size of dinosaurs! Scary, right? If the Earth’s oxygen levels would double, at 42%, these creepy-crawlies would be even bigger than before.

More oxygen means bigger creepy crawlies everywhere!

But don’t worry! Double the oxygen ensures that you can out-run all of these scary spiders! Due to the availability of more oxygen to the lungs, with every breath you take, your stamina would increase tremendously. Oxygen-rich blood would pump through your veins, fueling your muscles with energy, while increased blood circulation will give you greater agility and focus!

More oxygen means you will be able to run away from creepy crawlies much faster!

But don’t get too happy yet! Wait till the excess oxygen starts to weigh you down! With double the oxygen, the air density would also vastly increase. This means we will all experience increased air pressure and our ears will pop way more often! But that’s not the only problem.

While running away from all the giant creepy crawlies, we’ll have to watch out for something called ‘oxygen toxicity’. Too much oxygen in your bloodstream will cause rampant harmful oxidation in your cells causing them to die. So with double the oxygen levels, deaths due to fatigue and exhaustion will be more common than deaths from diseases!

With double the oxygen, deaths due to exhaustion will be more common

A higher oxygen concentration would lead to a thicker atmosphere, which would scatter more sunlight. So the sky would look beautifully bluer but you may feel colder as the overall temperature drops.  

Going back to our birthday candle, one of the most significant changes will be the increase in the rate of fires and combustion. Forest fires will spread much faster and flames will rise much higher than usual. Meanwhile, plants will get lesser carbon dioxide from the atmosphere so photosynthesis will slow down. Most of the earth’s green vegetation might be replaced with moss and fungi.

We should actually consider ourselves lucky to find ourselves at a time with such a finely balanced atmosphere. Too little oxygen and harmful radiation from space would have burnt everything crisp. Too much oxygen and all the dreadful possibilities described above could become a reality. We are, in a way, extremely lucky to have just the right amount of oxygen and we should do everything we can to keep it that way!

Do you want to ask your own ‘What if?’ question? Fill the form below and stand a chance to be featured on the Learning Tree Blog.

Submit your own question!



Leave a Comment




January 22, 2021
2 big asteroid will paas close to the Earth in next 5 days.


September 5, 2020

It is
Amazing knowledge Thank you byjus ☺️?

Analin Jacob

September 1, 2020

I liked the way how they teach and explain different topics and also respond to our doubts. It is so nice and wonderful. Love the way of learning from Byjus

Damanveer Kaur Chahal

August 30, 2020

Uh!I worried to listen about so many problems while oxygen gets doubled . Thanku God! That this was not true and we fell very lucky also .Thank you Byju’s to share such a beautiful fact!l


August 30, 2020

One thing more : if the temperature drops too low forever then we’ll face another ice age! Now we are not accustomed to low temperatures like the Neanderthals so it would be a really dangerous situation.
By the way, interesting possibilities BYJU’S and equally intersting series!

Sammi Kumar

August 29, 2020

Wow!I liked the new information that I got. I have submitted my doubt . I would also like to tell to everyone and my doubt is
Why does apes still exists in the nature if all of them evolved into homosapions.

Manashvi Singh

August 25, 2020

Woah nice information 😀 I have submitted my “What if” question , I hope it gets featured. Amazing information.

Amogh Kottada

August 25, 2020

Interesting. I already posted few questions. I liked the idea very much.

Alokendra Mandal

August 24, 2020

Wow! This is a great series as it reveals the impact and characteristics of the element in the remaining part of the question after ‘What if’!!??

Astha Bhardwaj

August 24, 2020

It is amazing. Thank u byjus for this interesting knowledge vine?


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