How long will the earth stay in good nick?

[Simon_Jester]

Okay. Just wanted to see it spelled out; I figured that if it were plausibly possible for Earth to fall into a Venus-like steady state of super-greenhouse atmosphere, it would have already done so.

[The Infidel]

I'm sorry to say, but I think we're screwed quite good. Since I was born (1970), about 60% of life is extinct. I remember winters in Norway being much colder than today when I was a kid, and my mother remembers the winters as even colder. The heatup of our planet is about to sustain itself. More co2 makes everything a bit warmer, permafrost thaws and methane is let out. Methane is a much more potent greenhouse gas than co2. Ice melts and less infrared light from the sun is being reflected back to space, heating up the planet even more. The seas take up a lot of co2, but the acidity of the water increases as a result, and lots of sea life doesn't really like that or warmer water.

We're already in a mass extinction, and on earlier mass extinctions, the apex animals are the one who bites the dust first.

Life will prevail. It has survived bigger fuckups than this, but we, and a lot of other animals, might not. Earth will not become a hellhole like Venus, but it really doesn't have to.

[Simon_Jester]

I'm sorry to say, but I think we're screwed quite good. Since I was born (1970), about 60% of life is extinct.

Hm. Would you mind citing that?

I remember winters in Norway being much colder than today when I was a kid, and my mother remembers the winters as even colder.

Have you recently examined climate data to judge how much colder?

The heatup of our planet is about to sustain itself. More co2 makes everything a bit warmer, permafrost thaws and methane is let out. Methane is a much more potent greenhouse gas than co2. Ice melts and less infrared light from the sun is being reflected back to space, heating up the planet even more.

This is a statement that has to be supported by mathematical models, not just rhetoric. My impression to date is that while some models show heavy self-sustaining heating, others show the heating tapering off at a relatively moderate level.

We're already in a mass extinction, and on earlier mass extinctions, the apex animals are the one who bites the dust first.

Interestingly, in this particular mass extinction, the largest cause of death of the apex animals is largely unrelated to the cause of death for everything else. Terrestrial megafauna and many oceangoing megafauna (like whales) are in danger from direct competition and predation by humans. If it weren't for conservation laws making it illegal to hunt (for example) lions, lions would probably be entirely extinct by now- because in places where humans live close to lions, humans generally want the lions dead. Once the humans obtain hunting rifles, it doesn't take long for them to get what they want. Even if climate change were not a factor, the proliferation of 19th century weapons technology would be enough to put those species on the endangered/extinct list.

By contrast, many smaller species (including ones at the bottom of the food chain) are in much more danger from things like ocean acidification and direct temperature/rainfall shifts that ARE caused by climate change.