Climate change. Pandemics. Nuclear war. While these are undoubtedly devastating realities or possibilities, could they wipe out humanity entirely? Highly unlikely, writes Seth Shostak, senior astronomer for the Search for Extraterrestrial Intelligence (SETI) Institute. From Quartz:
A century ago, the Spanish flu caused a staggering 20-50 million deaths, more than WWI. Still, the toll amounted to less than 3% of the world population. As ghastly as it was, the Spanish flu didn't even rise to the level of decimation; viruses can slay, but they can't annihilate. If past mortality is prologue, a millennial has less chance of succumbing to a new pandemic than dying in an auto accident.
OK, well what about climate change, now recognized as a non-hoax by 75% of Americans? It's not the heat per se that will waste us, but the knock-on effects. Low-lying nations will turn into aquariums and Caribbean countries will be pummeled and pelted by savage storms….
The World Health Organization estimates that between 2030 and 2050, 5 million people will perish due to the consequences of climate change. Nonetheless, if aliens visit Earth in 2050, they'll still find billions of humans. Indeed, probably more than walk the planet today…
However, there's at least one lethal bullet we might never be able to dodge: a gamma ray burst. This cosmic phenomenon could sterilize our planet in short order. Such bursts are not frequent—they're thought to be the final gasps of collapsing, massive stars—but if one were to occur in our own galaxy, the results could be truly catastrophic, resulting in destruction of our protective atmosphere. There would be no warning of such an event. But although lethal, nearby gamma-ray bursts are also very rare. We might never see such an event in all the future history of humankind.
And more on this topic from Columbia University and NASA climate scientist Kate Marvel: "Climate Change: We're Not Literally Doomed, but…" (Scientific American)