[Katie King (OP)]

Christine wrote in to ask:

"How much time have we, as humanity, left to prevent the point of no return for our climate?"

How long do you reckon we have left?

[alancalverd]

If you look at the data from the Vostok ice cores, we've been here every 100,000 years for at least the last half million years, and slowly returned to an ice age each time. http://euanmearns.com/the-vostok-ice-core-temperature-co2-and-ch4

I haven't seen a convincing explanation of how it happened (I'm not allowed to post my own here) but unless the laws of physics have changed, there's no reason to suspect it won't happen again.

[Origin]

Christine wrote in to ask:

"How much time have we, as humanity, left to prevent the point of no return for our climate?"

How long do you reckon we have left?

Nobody knows for sure.  That is why it seems like a pretty dangerous experiment we running on the earth, IMO.

[Origin]

If you look at the data from the Vostok ice cores, we've been here every 100,000 years for at least the last half million years, and slowly returned to an ice age each time. http://euanmearns.com/the-vostok-ice-core-temperature-co2-and-ch4

We have never been here before, man made global warming is unique.

I haven't seen a convincing explanation of how it happened (I'm not allowed to post my own here)

When it comes to science I always go with the experts, so in this case I listen to Climatologists and not anonymous people on the internet or politicians.

[Bored chemist]

we've been here every 100,000 years

No.
The rate of change in CO2 levels is unprecedented.

in this case I listen to Climatologists and not anonymous people on the internet or politicians.

Even asking a cartoonist is likely to work.

https://xkcd.com/1732/

[alancalverd]

Ignoring 95% of the evidence is never a good starting point. On my planet, 20,000<<500,000. But the present cycle which began around 25,000 BC looks pretty much like all the others so far.

[Zer0]

Hello Katie King!
🙏
On behalf of All of Us here, Welcome to the Forum.
(You need not respond, it's understandable)
👍

Thank you for such a sensitive & concerning question Christine.
(I'm no expert, but still i know, things are changing, i am my own witness)

" Finally, Earth is currently in an interglacial period (a period of milder climate between Ice Ages). If there were no human influences on climate, scientists say Earth’s current orbital positions within the Milankovitch cycles predict our planet should be cooling, not warming, continuing a long-term cooling trend that began 6,000 years ago. "

Original Source -
https://climate.nasa.gov/blog/2949/why-milankovitch-orbital-cycles-cant-explain-earths-current-warming/

Special Thanks - Alan Buis/NASA JPL.

Ps - I'm not sure about how much time All of Us have left, but i can sense & feel that it has already begun.
🤞

EDIT - hmm, a bit skeptical currently.
Cause the Info i provided states that the Planet should be cooling, but it's not, & staying warmer.
Hence a bit confused as to whether warm climate is better, or cold climate.

[evan_au]

I think that Earth would have to be pretty far gone to end up like Venus - and that probably will happen as the Sun uses up its Hydrogen fuel.

The current problem has to do with habitat loss/fragmentation and increasing temperatures.
- This pushes the habitable zone of a species towards the poles - provided there is a continuous habitat all the way there. But habitat fragmentation means that many species cannot move towards the poles
- And/Or this pushes the habitable zone of a species up mountains - provided there is a continuous habitat all the way there.
- So some species will die on the shores of an ocean that they can't cross, and others will die on the tops of mountains
- Genetic drift will be able to compensate, to some extent, but there are concerns about the speed of the change required
- Transplanting species to other continents may cause disruption of other ecosystems
- Zoos might provide a temporary respite for remnant populations

So I expect that the planet will recover eventually in the next glacial period, but in the meantime, we will have lost many species.
- The species that survive will be the weeds that can live anywhere
- And the humans:- provided some very nasty pandemic doesn't take us all out (are humans another weed species?)

[Bored chemist]

Ignoring 95% of the evidence is never a good starting point. On my planet, 20,000<<500,000. But the present cycle which began around 25,000 BC looks pretty much like all the others so far.

Again, you are making a false claim.
It doesn't look like the others.
It is a hundred times faster.

"Measurements from older ice cores (discussed below) confirm that both the magnitude and rate of the recent increase are almost certainly unprecedented over the last 800,000 years. The fastest large natural increase measured in older ice cores is around 20ppmv (parts per million by volume) in 1,000 years (a rate seen during Earth’s emergence from the last ice age around 12,000 years ago). CO2 concentration increased by the same amount, 20ppmv, in the last 10 years"
From
https://www.bas.ac.uk/data/our-data/publication/ice-cores-and-climate-change/

[Petrochemicals]

Depends on the definition of point  no return. For animal life, plant life, for human existence, or great whites on the east coast?

[alancalverd]

"Point of no return" seems unlikely in the foreseeable future. If humans are responsible for climate change, it will almost certainly limit human activity before all the methane clathrates are vaporised. Looking at chalk deposits, it's pretty clear that the planet had enough water to support life when there was a lot more carbon dioxide in the atmosphere, so microorganisms will eventually restore something approaching a pre-human ecology when we have made it uninhabitable for ourselves.

[walnutclose]

"How much time have we, as humanity, left to prevent the point of no return for our climate?"

Depends on your meaning for "point of no return."  If you mean, when do we get to where we cannot avoid in the lifetime of the next several generations of humans, significant and disruptive impacts, we're already there.   The more we add to the forcing function, the more significant those impacts become, but we've already locked in quite a bit of anthropogenic change.

If you mean, as some do, when do we get to the point where Homo sapiens is doomed, likely never, unless our response to climate change is to start a nuclear war and induce nuclear winter, civilization may take one hell of a beating, but enough net primary productivity in the biosphere will survive that humans will likely survive.

If you mean, when do we wipe out life on earth - not going to happen.   Life on earth has survived and come roaring back from far worse cataclysms than what we're doing.