Science Behind the Fiction: Netflix IO's poisoned Earth is a real possibility

The new Netflix original movie IO begins bleak and gets bleaker. In an unspecific but recognizable near future, humanity faces the consequences of unchecked climate change. After decades of allowing pollution and human-driven climate change to go unabated, the Earth's atmosphere becomes suddenly toxic to humans and the whole of the species is forced to abandon ship or die.

The Exodus program is set up to get everyone offworld and to a space station around Jupiter's moon Io while we try to find a new habitable planet elsewhere in the galaxy. Meanwhile, on Earth, pockets of humanity have remained behind at the behest of Henry Walden, a famous scientist who believes the world is salvageable and should not be abandoned. But by the time the movie begins, we know his plans have failed and most of humanity has either left home or died as a result of starvation or the poisoned air.

Sam (Margaret Qualley), Walden's daughter, remains at his lab and continues his work with bees and other animals in an attempt to find genetic strains capable of surviving in the new atmospheric conditions.

The specifics of the worldwide apocalypse in IO are glossed over in favor of resultant narrative, but we get hints about what happened. We get the impression this all happened rather rapidly. There are several scenes of Sam outside, clad in an oxygen mask, using a lighter to test the contents of the surrounding air. The flame burns purple, and while this is never overtly explained, it suggests atmospheric composition is less than normal.

While these were likely just convenient narrative devices allowing the setup of a post-apocalyptic scenario in which a tale of sacrifice and survival could be told, the setup of IO and the later consequences, terrifyingly enough, aren't totally outside the realm of possibility.

RAPIDLY CHANGING ATMOSPHERE

We've been living with the reality of human-caused climate change for about as long as any of us can remember. In fact, Svante Arrhenius, a Swedish scientist, recognized the changes occurring as a result of burning coal as far back as 1896, though his conclusions weren't quite so apocalyptic.

More recently, however, we've known that burning fossil fuels would come around to bite us sooner rather than later. It's been the slow scourge just over the horizon for a long time, but we have, collectively, been slow to react. There are many factors that contribute to our resistance to change. There are economic influences, political leanings, and there's also the fact that those groups most responsible for fanning the environmental flames are also those least likely to be negatively impacted in the short term. Probably the biggest hurdle to effectively tackling climate change, though, is how slowly it progresses.

Climate change is unlike any other problem humanity has encountered. We're used to easily quantifiable threats. But climate change has no single face, no definable territory, and it works on timescales of decades and centuries. For a species evolved to face down sharp-toothed predators who growl and pounce, climate change is the perfect enemy. It comes on slowly, can't be boxed in, and can't be slain. It is the proverbial slow-boiling pot and we are the frog. We're content to relax in the warmth because, even though the water is beginning to bubble, it likely won't do us in today. But what if it did?

While the level of greenhouse gases being introduced to the atmosphere increases every day, as a result of modern living, we're moving toward a previously unexpected sudden increase not accounted for in previous projections.

Large stores of organic carbon are locked in arctic permafrost, soil that is frozen year-round. As temperatures continue to rise, that soil will thaw and microbes will convert that carbon into carbon dioxide and methane at rates previously unseen. Moreover, this process is self-reinforcing. As the permafrost thaws and ancient greenhouse gases are released, temperatures will rise higher, driving additional thaws and releasing more gas pockets.

Right now, the Arctic is actually a carbon sink. Plants absorb more carbon during the growing season than is emitted in the region, but that could change as permafrost thaws. According to the National Snow and Ice Data Center, there is an estimated 1,400 gigatons of carbon frozen in the Arctic, more than one and a half times the carbon present in the atmosphere worldwide. If the thaw cycle were to reach a tipping point, it could have drastic implications with relatively rapid consequences, and there is evidence this is already happening.

THE COLOR OF FIRE

Sam Walden, the protagonist of IO, uses a lighter to test the air for toxicity. In the film, her lighter burns purple, warning her that the air is not safe despite the survival of at least one pig. While her method of testing might seem quick and dirty, the color of fire is actually a good indicator of what's being burned.

In everyday encounters, the color of a flame correlates to the temperature of the burn, with red flames being the coolest (in terms of, y'know, fire) and blue or white being the hottest. You've likely seen this while sitting around the campfire. This same phenomenon can also be seen in the color of stars, with red stars being the smallest and coolest while blue giants are huge and raging, doomed to burn through their fuel in a cosmic minute.

But the color of fire can also be an indicator of the type of fuel being burned. This is the primary idea behind spectroscopy, the study of electromagnetic radiation. Anyone who has ever encountered a rainbow has been an unwitting participant in spectroscopic study; when light fractures through a prism or a raindrop, what you're seeing is the variation of radiation emitted along the visible light spectrum.

If you were witness to the recent lunar eclipse, you were treated to a moderately rare instance of at-home spectroscopy. During a lunar eclipse, the Earth completely blocks the path of light between the Sun and the Moon, so why doesn't the Moon go dark? The Earth's atmosphere bends the sun's light around it, filtering out all of the spectra but the red. As a result, only the red light reaches the Moon and reflects back. It's the same process that creates the sunrise and sunset you encounter each day. In effect, the Moon is receiving every sunrise and sunset the world over, all at once. It tells us something about the makeup of our atmosphere, and it looks incredible.

This same process is used by astronomers to determine the composition of atmospheres around exoplanets. When viewing interstellar planets, we are, in a manner of speaking, participating in a long-distance eclipse. Some of the light of the parent star passes through the atmosphere of that distant world and on to our telescopes. By measuring the light that passes through the atmosphere, we can infer its makeup.

The wonderful thing about physics is, what happens elsewhere in the universe happens here as well. By changing the type of fuel being burned in a fire, you can change the color of the flames. This is the process that allows us to create fireworks of varying hues. All that's needed is oxygen, a heat source, and something colorful to burn.

Hypothetically, a fire burning in an atmosphere different from our own might have different properties due to the amount of oxygen and other chemicals in the atmosphere. If the quantity of certain greenhouse gases were to change dramatically, it is feasible that the color of flames might change along with them.

GETTING OUT OF DODGE

When the world finally fills with toxic gases and the ground bursts into purple flame, it might finally be time for us to wipe our hands, admit we totally mucked this one up, and find a new place to live. It might be happening already, but where do we go? In IO, humanity camps out near Io and prepares to search for a new home around a distant star. If the human race really had to pull up stakes, where could we go?

Provided we had the will and the technological know-how to get there, there are a few places that might be ready and waiting for us to set up shop.

To date, almost 4,000 exoplanets have been discovered, with more than 5,000 more waiting to be confirmed. But of those many thousands, only 15 are considered potentially habitable, and some estimates put that number even lower.

Of that handful of potentially habitable planets, most are much too far away for us to ever hope to reach them. Kepler 186-f was the first Earth-like exoplanet to be discovered. The roughly Earth-sized planet exists within the Goldilocks zone of its parent star, where water could exist. But it receives only about 30 percent the solar energy as Earth, meaning it might be much colder. More importantly, it's about 500 light-years away, far beyond our reach.

Another possible location is the TRAPPIST-1 system, a group of seven planets orbiting a dwarf star. Each of these worlds is thought to be Earth-like, giving future colonists several options to choose from. It's even suspected that some of these worlds might hold 250 times the amount of water as Earth. It just might be a great place to investigate just as soon as we can figure how to traverse the nearly 40 light-years to get there.

Our best bet, in terms of distance, at least, is Proxima Centauri b. At only 4.2 light-years away, it is the closest exoplanet we'll ever find. Proxima Centauri is one of the stars that make up the gravitationally bound Alpha Centauri system, Sol's closest stellar neighbor. This planet is about 30 percent bigger than Earth and receives about 70 percent the solar energy we do. But Proxima Centauri B is no Eden. It's tidally locked, meaning there is no day-night cycle, leaving one side of the planet perpetually hot while the other remains forever in the frozen darkness of night. Additionally, Proxima Centauri is an active dwarf star prone to flares. It might be nearby, but it isn't exactly a nice neighborhood.

All things considered, we've got it pretty good here despite the current and upcoming environmental hurdles. While the exploration of the solar system, the galaxy, and the universe is something humanity should continue to pursue, we'd do well to ensure we remain happy and healthy at home long enough to reach the stars.

IO is available now on Netflix. Catch it before the world burns.