Fresh on the heels of the recent news surrounding the increasingly dire climate forecast for our planet, comes a possible warning from the cosmos: climate change in extraterrestrial environments is inevitable and, should life on hypothetically habitable worlds not act as a stabilizer for their environments, it serves as a “sell-by” date for all burgeoning lifeforms.
In new research published in the journal Astrobiology, astronomers of The Australian National University (ANU) pondered this scenario and realized that young habitable planets can become unstable very quickly. What once was a life-giving oasis becomes a hellish hothouse or frozen wasteland very quickly.
“The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens,” said Aditya Chopra, lead author of the paper. “Early life is fragile, so we believe it rarely evolves quickly enough to survive.”
“Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable,” he said.
Unlike Earth, most worlds will likely not find this balance, ultimately succumbing to being cooked by a runaway greenhouse effect (like Venus) or frozen by a thinning atmosphere (like Mars). Life will often not be fortunate enough to win the race against environmental fluctuations to become a stabilizing factor.
Earth, which already has the stunning fortune to exist at just the right spot around a stable star, spawned life and that life had a role to play in stabilizing its atmosphere as it evolved over that last 4 billion years.
“Life on Earth probably played a leading role in stabilizing the planet’s climate,” said co-investigator Charley Lineweaver, also from ANU.
And this could be why we’re not finding a galaxy filled with alien life — just because there’s a habitable world out there, it doesn’t mean it’s suitable for life for long. It’s yet another hurdle against life from gaining a foothold.
“The mystery of why we haven’t yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces,” said Chopra.
For now, this is all speculation, but what’s clear from observations of our own planet, is that the mother of all existential self-inflicted bottlenecks is on the horizon and, unless we find a way of reversing the damage we’ve caused to our environment, it seems we’ll quickly become just another lifeform that didn’t make the grade.
Source: ANU press release