It will take more than nuclear winters, volcanoes, or asteroids to wipe out life on Earth. Short of a supernova or another event that heats the surface of the earth to hundreds of degrees Centigrade, everything from archaeic bacteria to tardigrades will survive any catastrophic event and eventually more complex life will evolve again. The earth's biosphere will far outlive any civilization.

But we're not talking about tardigrades and bacteria: we're talking about millions upon millions of species that do have complex interdependencies with each other and the environment in general. We have no way to predict which species, when together decimated, might drastically impact our survival because they hunted pests that killed major oxygen producers or transmitted diseases through different animal and human populations. We have no way to know where in the equilibrium we are and which levers might set off a catastrophic downward spiral.

Hell, if there is a nuclear winter or asteroid impact, we are far enough along technologically that many humans, maybe even millions, would survive and rebuild civilization (say using nuclear power, chemical engineering, desalination, and hydroponic agriculture to survive underground until the environment clears up). I guess it just depends on how you define the biosphere and survival.

We survived one back in the sixth century [1]. There's some speculation that the European Dark Ages were caused by this impact rather than the end of Roman rule (the traditional interpretation).

But the biosphere got itself back to its previous state remarkably quickly, apparently, though it's hard to tell if that event contributed to the end of the Medieval Warm Period and the start of the Little Ice Age.

[1]http://www.dailymail.co.uk/sciencetech/article-1248518/Did-a... apologies for the appalling quality of the reference but I couldn't find the journal articles from google.

There's no rule that says the biosphere has to be resilient in every dimension we might push on it. If the biosphere has been stressed in a particular way and life (animal and mammalian life, specifically) rebounded, that does not mean the biosphere is resilient to any other kind of stressor, and it's only mostly assured that it's resilient to that particular one because of empirical evidence. We don't have models accurate enough to confirm your suspicions about the hardiness of the biosphere. There may be an attractor to current life-supporting conditions even under a broad range of stressors, but if human progress is adding an additional stressor (that we may not even recognize), we could be screwed.

Agreed, it doesn't mean those things. But I think that when we say we'll be "screwed" it doesn't necessarily mean the earth will be fundamentally different after the screwing is completed. The dinosaurs got screwed, and so did the Neanderthals, and in the end all that did was make room for us, the latest species about whom the Earth cares not at all.

That humans will impact the planet is a certainty. Like all species, it's constantly "screwing" the environment. The missing link is that, in turn, the environment "screws back". This exogenous will force humans into adaptation - only failing that comes the extinction scenario.

So it's not like we have a choice. Unless the entire species subscribes to nihilism (which I doubt it's at our core, or we wouldn't be here today), we have to adapt.

Sure, no matter what we do, life will find a way to continue and flourish, probably without us. But the point is, we care about Earth supporting us.

I think this dialogue pretty much sums it up: http://i.imgur.com/o79ym.jpg.

We're fucking ourselves over big time and we won't be missed.

original link: http://humoncomics.com/mother-gaia

the image you posted has a footer atribution that has nothing to do with the comic.

But most people seem to be concerned with Earth continuing to support our particular form of life.