Space

Study calculates how lucky we are to have a habitable planet

The odds of habitable conditions lasting long enough for the development of complex life are very long according to a new study
The odds of habitable conditions lasting long enough for the development of complex life are very long according to a new study

New research involving the simulation of 100,000 random worlds suggests that chance played a major role in allowing Earth to maintain a habitable environment for the three to four billion years needed for the evolution of complex life.

Earth hasn’t always been the most pleasant place to live. It’s history is riddled with ice-ages, periods of unpleasant volcanism and even the odd cataclysmic asteroid impact.

Cyclical mass extinctions and climate shifts have brought life on Earth to the brink numerous times. However, the extraordinary fact remains that our home planet has somehow managed to remain continuously habitable for the past three to four billion years – long enough for single-celled life forms to evolve into human beings.

In a new study, Professor Toby Tyrrell, a specialist on Earth system science at the University of Southampton, set out to shed light on how our planet has managed to remain habitable, and to what extent luck may have played a role in its continued success.

To this end Professor Tyrrell used the Iridis supercomputing facility located at the University of Southampton to model 100,000 randomly different worlds. He then simulated how their evolutionary paths, and therefore their temperatures, were affected by climate-altering events over the course of three billion years.

The evolution of each digital planet was simulated 100 times, and for each run different random events were inflicted upon the worlds.

It was discovered that out of the 100,000 planets, only one was able to maintain habitability for all 100 of its simulations. The remaining worlds that were able to maintain a temperature suitable for sustaining life for three billion years were only able to do so in some of their simulated histories, and thus had a probability of being habitable rather than a certainty of it.

Nine percent, or 8,710, of the digital planets were found to be habitable for three billion years in at least of their 100 simulated runs. Of these, roughly 8,000 worlds had a success rate of less than 50 in 100, and 4,500 of the planets were habitable less than 10 times out of their 100 simulations.

According to the author the results suggest that Earth’s habitability was not a simple inevitability, but rather that our planet, or rather every currently living species on it have been statistically lucky regarding the environmental calamities that life on our world has been forced to endure.

"We can now understand that Earth stayed suitable for life for so long due, at least in part, to luck," explains Professor Tyrrell. "For instance, if a slightly larger asteroid had hit Earth, or had done so at a different time, then Earth may have lost its habitability altogether. To put it another way, if an intelligent observer had been present on the early Earth as life first evolved, and was able to calculate the chances of the planet staying habitable for the next several billion years, the calculation may well have revealed very poor odds."

The paper has been published in the Nature journal Communications Earth & Environment, and Professor Tyrrell discuses his research in the video below.

Source: University of Southampton

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15 comments
Eezy
There is another simulation evaluation required. Not only has the planet been habitable, but the referenced evolution of life on the planet has gone from a cell to many varied life forms. You have a lucky habitable world inhabited by a lucky evolution of life. Combine the probabilities of both occurring. Is it probable without external intervention?
matt43
Yeah, "lucky"... Couldn't be that it was all created exactly this way to make scientism practitioners go absolutely insane... no, we need another few decades of them insisting we're all here by "chance". Nevermind the organic chemistry required to synthesize the necessary components is literally impossible to happen by "chance".
Bob Stuart
The recent ice ages were teeming with life. There was more exposed seabed in the tropics, and more oxygen in the surrounding seas. They only seem formidable in places that show glacial scars.
buzzclick
We are indeed fortunate to have this planetary orb as our home. Let's hope we don't blow it by the end of this century. It would make our alien overwatchers very disappointed.
michael_dowling
Chance it may be,but if we were on any of the other simulated worlds,we wouldn't know it,because we wouldn't have evolved. Yes,Eezy,it is possible. There are more habitable worlds in the universe than there are grains of sand on all the beaches of this world,and more uninhabitable worlds than all the sand on a million earths. The universe is bigger than our tiny minds can grasp.
TonyB
When you consider the billions of solar systems with planets in our galaxy, and the billions of galaxies in the universe, it seems very likely that the accident of life has occurred many times throughout the universe. Indeed, it has occurred many times on our planet. Nature is truly amazing.
Marco McClean
That's not the way to think of the odds. Life is nearly impossibly unlikely, sure, but the universe is very big and very old. Ours is the one chance out of uncounted quadrillions that /did/ end up with us developing. And our time is our timeframe. The odds are actually 1:1, /because/ we're here to marvel at how unlikely we are. In all the gazillions of places and times where there isn't and wasn't intelligent life, there's nobody doing any marveling (or praying) at all.
Signguy
When science looks at the incredible balance of required elements and "laws of nature", not to mention the incredible balance in space for the worlds to even exist; it's been DESIGNED that way, & we have not, and never will, discover any other inhabitable planet; God designed in this way in His plan.
Law of Entropy proves evolution to be crap.
Bruce H. Anderson
We are here by happenstance. What morality we assume to have is a product of our own hubris. When we die there is nothing. Kinda makes you feel all warm and fuzzy, doesn't it?
Kpar
"New research"? One might take a look at the book "Rare Earth, by Ward and Brownlee published in 2003. Truly comprehensive, it examines many of the truly rare characteristics that make our planet habitable. I am sure that was the original basis for this new work, combined with the many results of the Kepler exoplanet search- all those planets, but none (so far) have the necessary attributes. The original Drake equation was ridiculously optimistic.