I put the very simple question to the scientists. When, in the earths history has climate not changed? Now get this, one loony is trying to marry up climate change as a reason we will never have aliens come visit us. I think this whacko has been snorting way too much space dust for his own good. One thing he does concede is that there is the probability of other life out there somewhere. God bless him, common sense dictates that alone. If Steven Spielberg thinks there is that’s good enough for me.
The reason some scientists think we’ve never found aliens implies humans could go extinct sooner than we realise
Why haven’t we heard from aliens or found any evidence of their existence? That question is known as the Fermi paradox, and there are a number of potential answers to it (most are fairly disconcerting).
One hypothesis is that before intelligent life manages to spread beyond its original planet to other nearby planets, it runs into a sort of “Great Filter.”
As philosopher Nick Bostrom explains it, this idea suggests there are several “evolutionary transitions or steps” that life on an Earth-like planet has to achieve before it can communicate with civilizations in other star systems. But some sort of obstacle or barrier may make it impossible for an intelligent species like ours to get through all those steps. That would explain why we haven’t heard from or seen any other life.
You start with billions and billions of potential germination points for life, and you end up with a sum total of zero extraterrestrial civilizations that we can observe. The Great Filter must therefore be powerful enough — which is to say, the critical steps must be improbable enough — that even with many billions of rolls of the dice, one ends up with nothing: no aliens, no spacecraft, no signals, at least none that we can detect in our neck of the woods.”
Humans’ great filter
Climate change caused by the development of advanced civilisation could very well be that filter in our case. David Wallace-Wells suggested this possibility in a recent feature for New York Magazine:
“In a universe that is many billions of years old, with star systems separated as much by time as by space, civilizations might emerge and develop and burn themselves up simply too fast to ever find one another. Peter Ward, a charismatic paleontologist among those responsible for discovering that the planet’s mass extinctions were caused by greenhouse gas, calls this the “Great Filter”: “Civilizations rise, but there’s an environmental filter that causes them to die off again and disappear fairly quickly,” he told me. “If you look at planet Earth, the filtering we’ve had in the past has been in these mass extinctions.” The mass extinction we are now living through has only just begun; so much more dying is coming.”
Scientists are currently debating whether we are now in the midst of the Earth’s sixth mass extinction event or simply approaching it. Either way, the situation is dire — the existential risks posed by a worst-case climate change scenario are real.
If those risks do eventually become serious enough to act as humans’ “Great Filter,” it may be too late for us to communicate with anyone else in our universe.
Read more at https://www.businessinsider.com/climate-change-great-filter-fermi-paradox-aliens-2017-7#Do3uFKQYQOo8YsCC.99