[jermaustin1]

How long did it take to oxygenate the planet though? Millions of years, billions?

How long did it take to spew enough carbon into the atmosphere to create acid rain? How long did it take to clear cut most of the wester European forests?

No one thinks the earth was perfectly harmonious before man, but in the last 200k years (0.0004% of the earth's age), we have DEFINITELY left a mark that no other life form before had. In the last 200 years, we've probably done more harm than all other life forms before as well (but that I'm less confident about).

[sfn42]

That carbon we're spewing into the atmosphere was once part of the atmosphere. We're just putting it back.

Similarly, life forms are responsible for removing it, producing oxygen etc. The planet has gone through multiple mass extinctions, ice ages etc, it has changed much more significantly and over short time periods before.

That's not to say we shouldn't be reducing emissions and trying to reduce our impact. I just don't like this argument that seems to me like it's based on trying to guilt people - "The earth was fine until we ruined it!", it's bullshit. The earth is a planet, we do not have the capability of destroying it. We can change it so we and many other life forms can't live here any more but it will still be a planet and there will most likely still be some form of life here for millions of years to come.

The problem is we are shitting where we sleep, we are ruining our own home. If we take it too far, which we may already have done, we won't be able to live here any more, at least not in the way and scale we currently are. And we're certainly not living anywhere else any time soon either, so that means we screwed ourselves.

And when we're gone I personally don't care whether there's still dolphins or whatever. Life comes and goes. That's life. Everything will end, the sun will die and so will the universe. The only question is when.

Why anyone would care about what happens after we're gone is beyond me. What we need to prioritize is self preservation. And we rely on the current ecosystem so if we ruin it we ruin ourselves. But from the resulting apocalypse new life will form, which couldn't have existed without it. The earth will be fine, we might not be.

[jlaternman]

“We can change it so we and many other life forms can't live here any more but it will still be a planet and there will most likely still be some form of life here for millions of years to come.“

When people talk of destroying the planet, they do not mean obliterating its mass in a Death Star-like way. They’re just talking about destroying its ability to sustain life, and it seems clear we have the potential to trigger that change. It’s a small planet, and even if we had no knowledge of it, looking around in the universe suggests its ecosystems and atmosphere are fragile and can’t be taken for granted.

[southernplaces7]

>They’re just talking about destroying its ability to sustain life

You should really look deeper into the effects of large historical asteroid impacts and other major cataclysms. Literally, the worst that humanity could do even if it tried with current technology doesn't even come close to being so fantastically destructive. We could, tomorrow, start polluting the earth to the absolute straining maximum of our ability and follow this up with the launch of all our nuclear weapons everywhere in the world, and we'd kill ourselves off (or at least enough of us to no longer be able to continue our destruction efforts in a meaningful way) long before we'd more than pull off a tiny fraction of the destruction one large asteroid causes.

And no, we wouldn't at all ruin the Earth's ability to sustain life. Our planet and its ability to regenerate ecosystems has survived multiple impacts my massive asteroids, at least a couple of impacts by literal small planets, at least two total ice ages in which the planet turned into an essential snowball (think ice caps from pole to pole) and at least three massive magmatic events (that I can think of off the top of my head) spanning whole subcontinents worth of lava flow and multiple massive volcanoes erupting constantly, without pause, for hundreds of thousands of years, only for life to bounce back from all of this.

It's pure ignorant hubris to think that any human effort today could come close.

[jlaternman]

I agree that, obviously, large scale asteroid impacts and other major cataclysms have exponentially bigger immediate destructive outcomes. Ridiculously so.

That doesn't mean the atmosphere itself, and the weather systems governing them, don't have to be kept in balance from the inside. It's a different kind of threat, man-made effects on the planet, sustained and over time. Two different systems – one where the life-sustaining systems suffer an acute disruption but then can naturally restore itself over time, and another where the nature of the system itself could slowly be adjusted, potentially compromising its basic life-sustaining qualities.

I wouldn't say it's a bigger threat than large asteroid impacts or cataclysmic events – though, those are relatively minuscule percentages, where the other is something approaching 100% on our current trajectory –, but that doesn't mean it can be dismissed as a threat in itself to the planet's life-sustaining properties. Every threat merits attention, regardless of how they compare.

And the threat is not about human effort, it's about ignorant human hubris.

[thatcat]

SO2 and NOx produces acid rain

[jermaustin1]

My bad - point stands, just wrong element/molecule.

[thatcat]

I for sure agree with your sentiments. I added the correction because I thought the acid rain reduction program worked and was a good example of how regulation can work, but after looking it up again I found that the pH of rain didn't increase even though so2 emissions of power plants were significantly reduced.