Studies show that many animals understand some concept of numbers, such as one, two, and many. For example crows have been shown to be able to count to about seven. Arguably humans understand numbers better than any other inhabitant of earth, but it is without doubt that we lose our sense of scale at some point, perhaps in the hundreds of thousands or maybe a million.
However, there is much in the world that requires dealing with numbers in the millions, billions and trillions. Scientists deal with far greater numbers of course. I believe that the inability to understand scale is a major reason people fail to grip many important concepts and issues. The purpose of this series is to use simple math to re-analyze big numbers to show them on a scale we can easily relate to. Please feel free to check my numbers and my math!
For example, common sense would seem to dictate that humans cannot have a great effect on the planet as a whole, since earth is quite clearly a very big place. I believe this is a major factor in why many people reject that human activity could result in climate change. Let us break down the really big numbers into something we can more easily grasp.
The land area of planet earth amounts to 57.3 million square miles. If we subtract deserts and remote mountainous areas this drops to 24.6 million habitable square miles. (1)
The human population of planet earth is on the order of 7.5 billion human beings. (2)
7.5 billion humans divided by 57.3 million square miles = 131 humans per square mile of the planet!
7.5 billion humans divided by 24.6 million square miles = 305 humans per “habitable” square mile of the planet!
But the above numbers are still not too easy to grasp. A square mile is beyond easy comprehension for many of us! So let’s break this down further. 1 square mile = 27,878,400 square feet.
Therefore we can convert the numbers above into clearer numbers:
131 humans per square mile of planet = 131 humans per 27,878,400 square feet of planet
27,878,400 square feet /131 humans per square foot = 212,812 square foot of land per human
or if we disregards mountain and desert:
305 humans per habitable square mile of planet = 305 humans per 27,878,400 square feet of habitable planet
27,878,400 square feet /305 humans per square foot = 91,404 square foot of habitable land per human.
An American football field is 120 yards (360 feet) x 53.3 yards (160 feet) = 57,600 square feet.
So here is what the really big numbers are telling us:
If we look at the habitable landmass of the planet earth, there is roughly one human for every two football field-sized units of area!!! That demonstrates there are a LOT of humans, or not very much planet!
This is explains why we discovered, over 50 years ago, that just our excrement could cause major local environmental impact! If you consider that each of us is consuming food, burning wood, gasoline, etc etc, it suddenly becomes entirely plausible that our activities over hundreds of years could affect the planet! In the past few decades we have started seeing our impact on the oceans, which are far larger than the land area of the planet.
It also points to the fact that slowing (or reversing) population growth is essential to limit further damage to this surprisingly small planet
Tune in next time for more really big numbers and what they mean!
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NOTE: I apologize for the USA-centric units of measure. I am assuming my target audience is in the USA (the rest of the world accepts human-induced climate change).
Footnotes:
(1) www.zo.utexas.edu/…
(2) www.geohive.com/...