You’ve heard it said that life is fragile. It’s true. When you stop and consider the precision necessary for life, you can’t help but realize how precarious life really is. Take earth’s position in our galaxy for example. Earth is located in what is known as the habitable zone (also known as the Goldilocks zone). This region is the perfect distance from our sun for liquid water to exist in our planet. If the planet was any closer to the sun, water would vaporize; any farther and water would freeze. Water is absolutely necessary for our form of life to exist so as you can see, our existence depends on us remaining in this very limited, habitable zone.
Remarkable as it may be, the habitable zone is not the only precarious situation enabling life to exist. On today’s list, we’re going to go over 25 precise things that show hos precarious life really is. A slight deviation from any of these examples could spell the end of life as we know it. It’s a bit scary when you think about it and it’s definitely a reason to pause and consider. Life is fragile. We’re literally hanging by a thread.
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We begin this list with the tropospheric ozone. In simple terms, the tropospheric ozone is ground-level ozone. As it currently stands, if it were to increase in quantity, animals would experience respiratory failure. It would also hinder crop yields and ozone-sensitive species would die. However, if it were smaller, biochemical smog would destroy most life.
Our galaxy’s shape
Galaxies come in roughly four shapes: spiral, elliptical, lenticular, and irregular. The Milky Way galaxy is a prime example of a spiral galaxy though there are many more spiral galaxies out there. Our case as of this moment is unique as we are the only galaxy (so far) know to harbor life. If our galaxy was too elliptical, then the formation of stars would cease before sufficient amounts of heavy elements had the chance to form and create life chemistry. On the other hand, if our galaxy’s shape was too irregular, then we would have been exposed to harsh radiation which would inhibit the formation of life-essential heavy elements.
The frequency and extent of ice ages
This may sound a bit odd but it’s believed that if there were no ice ages or even fewer than what have occurred then Earth’s surface would lack fertile valleys, essential for advanced life. Moreover, mineral concentrations would be insufficient as well. On the other hand, if ice ages had been more frequent, then Earth would experience freezing temperatures that wouldn’t allow for any form of intelligent life.
The distribution of continents
Even the distribution of our continents have a direct impact on life as we know it. If our continents were distributed more towards the southern hemisphere, then sea salt aerosols would not be enough to stabilize our planet’s surface temperature and the water cycle. As a result, “increased seasonal differences would limit the available habitats for advanced land life”.
Earth’s atmospheric pressure
Our atmosphere is responsible for containing the air necessary for life and it also protects us from the harmful radiation emitted by the sun. Earth’s atmosphere is about 300 miles thick (but most of it is within 10 miles from the surface). The further up in the atmosphere you go, the less air pressure there is. For example, at sea level, air pressure is about 14.7 pounds per square inch, and at 10,000 feet, air pressure is 10 pounds per square inch. If there was less atmospheric pressure, liquid water would evaporate too easily and condense too infrequently to support life. However, if air pressure was greater, the opposite would be true, there would be inadequate liquid water evaporation to support life. Furthermore, not enough sunlight and UV radiation would reach Earth’s surface.