Is Earth heading for extinction?

*From full-blown collapse to gradual die off, math models reveal three possible fates for planet *Innovative zero-emissions power plant begins tests on new approach to capturing carbon

SCIENTISTS have modelled the three possible fates for our planet as Earth’s population grows and the effects of climate change worsen.

Mathematicians modelled how advanced civilisations on ancient exoplanets might have survived or perished when faced with a similar changing environment.

They showed that humanity could go through a soft landing, a gradual die off, or full-blown collapse.

Experts said a die-off, in which, as much as seven in ten of a planet’s inhabitants were wiped out before stabilising, was by far the most common outcome.

A soft landing was the most positive outcome, and occurred when a civilisation adapted to its changing planet without a mass extinction.

During a full-blown collapse, the planet was too sensitive to recover from damage caused by its inhabitants, leading to a rapid annihilation of all intelligent life.

There is bad news for Earth. Even when planets switched to renewable fuels to save themselves from extinction, the damage done was sometimes still enough to wipe out the inhabitants, according to the models.

Scientists said the simulations reveal “a radical truth about the challenge we face as we push the Earth into its humandominated era.”

The team, led by scientists at the University of Rochester in New York, used models for population growth on Earth to mark out how alien planets may have grown.

Using statistical models they mapped out possible histories of alien worlds, the civilisations they grew, and the climate change that followed.

They called these societies “Exo-civilizations” and say that learning from their mistakes could help us prepare for the effects of climate change.

Writing in the Atlantic, coauthor Professor Adam Frank said: “Given that more than 10 billion trillion planets likely exist in the cosmos, unless nature is perversely biased against civilisations like ours, we’re not the first one to appear.

“That means each exo-civilization that evolved from its planet’s biosphere had a history: A story of emergence, rising capacities, and then maybe a slow fade or rapid collapse.

“And just as most species that have ever lived on Earth are now extinct, so too most civilizations that emerged (if they emerged) may have long since ended.

“So we’re exploring what may have happened to others to gain insights into what might happen to us.”

Also, a team of engineers in La Porte, Texas, has spent the past several weeks running tests on a prototype power plant that uses a stream of pure carbon dioxide (CO2) — not air — to drive a turbine. If the zero-emission technology developed by NET Power in Durham, North Carolina, succeeds, it could help to usher in an era of clean power from fossil fuels.

The company broke ground on the roughly 25-megawatt plant in March 2016, after raising US$140 million for the project, and completed construction last year. It is now running a battery of tests on the combustor that powers the plant, a one-of-a-kind device built by the Japanese industrial giant Toshiba. If the tests go as planned, NET Power will hook up the turbine and begin generating electricity later this year.

Officials say everything is running smoothly so far. “We’re still smiling,” says chemical engineer Rodney Allam, the facility’s lead designer. Allam is now a partner with 8 Rivers, a technology company in Durham that co-owns NET Power with Exelon, a major electricity provider in Chicago, Illinois, and Mcdermott International, an energy-services company in Houston, Texas.

Meanwhile, the University of Rochester in New York team’s calculations combined population statistics from Earth’s species with generic physics and chemistry that make up climates on other planets.

They applied the laws of these climates to scenarios in which an industrial civilisation arrived on a planet and began consuming its resources.

As the society used up resources for energy, it grew because its capacity to feed more people expanded, allowing it consumes more resources.

Eventually this loop had feedback effects on the planet that damaged it and began to make it uninhabitable.

This mirrors humanity’s relationship with Earth following the industrial revolution, during which we began to burn fossil fuels for energy, Professor Frank said.

As part of the simulations, researchers imagined the civilisation had two types of energy source: One with a high impact on the planet, like fossil fuels, and one with a low impact, like solar power.