Why Can’t We Find Aliens? Climate Change Killed Them – As we look deeper into our galaxy for signs of extraterrestrial life, we keep drawing a blank. Does this mean life on Earth is unique and weโre the only ones out here? Or could it just mean that all the aliens are dead?
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 โsell-byโ 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.
โThe universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens,โ said Aditya Chopra, lead author of the paper. โEarly life is fragile, so we believe it rarely evolves quickly enough to survive.โ
โMost 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,โ 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.
โLife on Earth probably played a leading role in stabilizing the planetโs climate,โ said co-investigator Charley Lineweaver, also from ANU.
And this could be why weโre not finding a galaxy filled with alien life โ just because thereโs a habitable world out there, it doesnโt mean itโs suitable for life for long. Itโs yet another hurdle against life from gaining a foothold.
โThe mystery of why we havenโt 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,โ said Chopra.
One of the fundamental reasons for seeking out exoplanets, particularly small rocky worlds in orbit around their stars within their habitable zones, is to find planets that have similarities to Earth. And weโre finding plenty of candidates that approximately fit the bill. But just because they possess some โEarth-likeโ features certainly doesnโt mean theyโre Earth-like. This research underscores the uncertainty.
For decades weโve been pondering our place in the universe and tried to theorize why weโve uncovered no evidence for extraterrestrial intelligences. With all the stars and planets in our galaxy and all the water and prebiotic chemicals that are known to exist, there must be other intelligent lifeforms. But thereโs no sign of them. This problem is known as the โFermi Paradox.โ
Chopra and Lineweaver suggest their new research provides some answer to this paradox and call it the โGaian Bottleneck.โ If life isnโt given a chance to stabilize its biosphere, then itโs doomed.
Earth was given this opportunity, and life emerged from the Gaian Bottleneck to help form the life-giving oasis we take for granted today. Earth and its complex interplay of feedback cycles created what can be seen as a superorganism, where all life on its biosphere has a role to play in its evolution. (This is known as the โGaia Hypothesisโ, a relatively controversial idea formulated by James Lovelock and Lynn Margulis in the 1970s.)
But now we have an intelligent lifeform that emerged as a dominant force, interrupting and exploiting our planetโs natural cycles. Humanity has inadvertently created a new bottleneck โ letโs call it the โIndustrial Bottleneckโ โ by causing irreversible changes to our delicate biosphere. Now, weโre seeing rapid impacts on our civilization as the balance in our climate is knocked off-kilter by the inexorable rise of greenhouse gases from industrial processes and energy needs.
Are these bottlenecks common throughout the cosmos? If an extraterrestrial lifeform โmakes the gradeโ and survives the Gaian Bottleneck, does it then face another existential threat from their evolution into a industrial civilization?
For now, this is all speculation, but whatโs 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 weโve caused to our environment, it seems weโll quickly become just another lifeform that didnโt make the grade.
