The Goldilocks Zone

November 7, 2022
Earth from space with light flare to left side.

By Bob Buring, Naturalist and Nature Ranger

Whether you are a science fiction fan or not, you can probably imagine a very large vessel on a multi-year journey to another solar system. 

Given the hostile nature of space, surviving such a trip would require meticulous care of your ship, and the cooperation of everyone on board.

Our planet is hurdling through space at 67,000 miles per hour, much like the spaceship. We are protected by our atmosphere, held in place by gravity, and sustained by the environment’s ability to support life, both plants and animals.

Yet there are places where we cannot survive without extreme measures. On mountaintops, there is little oxygen and heat. Deep in the ocean, the pressure would crush us. In our arid deserts, there is no water. Antarctica is an unforgiving desert of frigid temperatures, violent winds, and storms.

Humans, most animals, and plants require a narrow range of environmental conditions to survive. 

We are all stewards on this ship we call Earth.

Most of us realize we inhabit a world unlike any other in our solar system. Earth is the perfect distance from the sun, allowing water to exist in liquid form, and temperate enough to allow our plants and animals to thrive. This fortuitous location is referred to as the “Goldilocks Zone”—not too hot, not too cold, but “just right.”

Another example of this analogy is our human geologic time placement.

When most of our sedimentary rock was formed, hundreds of millions of years ago, a large part of our continents was covered with a shallow sea due to a long warm period and little planetary ice. There was very little terrestrial life.

From 245 to 66 million years ago dinosaurs roamed the earth. As many were both massive and carnivorous, human proliferation at that time would have been nearly impossible. It was the demise of the non-avian dinosaurs that allowed mammals to evolve.

More recently, our planet has experienced a long “Ice Age,” beginning about 2.5 million years ago, with advances and retreats of large glacial sheets covering much of our continents. Within that period, the last advance was from 115,000 years ago until about 11,700 years ago, and the ice continues to retreat.

Man as a species has been on the earth only about 300,000+ years, long after the last period of continental seas and dinosaurs, but during the latest glacial periods.

During the last glaciation, all humans on earth were hunter-gatherers. Not until the last ice sheet began melting did our ancestors move toward organized cultures. 

It is safe to say modern man evolved and succeeded in part due to the absence of ice or water covering most land masses. We have been fortunate to have had maximum exposed terrain on which to grow our populations.

This is our biogeographic “Goldilocks Zone.”  

Assuming we need maximum real estate for the billions of humans to inhabit, we need the amount of ice on earth to be “just right.” Too much ice will result in glaciers returning and transforming much of our habitable areas into frozen wastelands. The other extreme will raise sea levels and partially cover the continents. 

Each of us plays a part in the preservation of our planet while it allows us to do so.