7 ms·

So, Ice Ball or Venus. Seems like climate is more sensitive than we think. Man made impact or not, the whole system seems on a knifes edge of tipping towards

So, Ice Ball or Venus. Seems like climate is more sensitive than we think. Man made impact or not, the whole system seems on a knifes edge of tipping towards the extremes. That we are living right now is rare in-between point.

boomboomsubban 3y ago
The process they described took millions of years. Yeah, we're probably in a somewhat rare in-between point. That "point" is still unimaginably long.
- somenameforme 3y ago
  Sediment cores show extreme temperature oscillations over far shorter time frames. This [1] is 5 million years of temperature reconstructions based on the Vostok ice cores. Keep in mind the scale, the difference between the peaks and valleys is 10 degrees celsius! But the really interesting thing is that that derived from this [2], which is Earth's temperature over the past 65 million years. Those previous extremes just blur, because now you're talking about a temperature difference of 20 degrees celcius, no ice on the planet, and giant beasts roaming in lush greenery. Greenery which was basically everywhere, even Antarctica! [3] ---- [1] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/media/File:Five_Myr_Climate_Change.png https://en.wikipedia.org/wiki/Geologic_temperature_record#/m... [2] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/media/File:65_Myr_Climate_Change.png https://en.wikipedia.org/wiki/Geologic_temperature_record#/m... [3] - https://en.wikipedia.org/wiki/Eocene#/media/File:Ypresian_Earth_50_mya.jpg https://en.wikipedia.org/wiki/Eocene#/media/File:Ypresian_Ea...
deepnet 3y ago
This balance is quite probably a very strong filter on the Drake equation. Climate and Biosphere is delicate with lots of tipping points and cascades to uninhabitable. A few billion years ago, the inner planets of the Sol system were capable of supporting abundant surface life - now only Terra.
pfdietz 3y ago
It could be the stability of Earth's systems is just an illusion created by observer selection. If it had not been within limits, we wouldn't be here. This places no constraint on how stable it will be in the future. Another part of the system that could be like that is the oxygen content of the atmosphere. The time constant for variation in O2 level is just a few million years (due to consumption of O2 by release of reducing gases and weathering of rocks to expose reduced materials like ferrous iron.) If it had ever dropped too much during the Phanerozoic higher life would have been wiped out. I don't believe any plausible feedback control mechanism has been discovered. In particular, fire involving plants (which couldn't have occurred before the evolution of large land plants) can be a positive feedback, as charcoal is very resistant to further oxidation and, when buried, represents a net increase in atmospheric oxygen. Maybe, if mankind explores the galaxy, we'll find all these formerly life bearing planets where stability failed.
- BirAdam 3y ago
  Stability is an illusion. It’s becoming increasingly evident that even small shifts in climate have triggered devastating events for humans, like the Bronze Age Collapse, plagues, and so on. Plus, there’s the whole end of the last glaciation that likely created the various flood myths and wiped out most of the megafauna.
  - pfdietz 3y ago
    Arguably Venus and Mars were more habitable than Earth in the earlier solar system. Both fell off the stability wagon and now are dead worlds (with possible survival of deep underground life on Mars.)
nicklecompte 3y ago
Keep in mind that becoming an ice ball likely led to significantly increased biodiversity, via Wikipedia: > Since 2009, some researchers have argued that during the Cryogenian Period, potentially the oldest known fossils of sponges, and therefore animals, were formed. However, it is unclear whether these fossils actually belong to sponges, though the authors do not rule out the possibility of such fossils to represent proto-sponges or complex microbial precursors to sponge-grade organisms. The issue of whether or not biology was impacted by this event has not been settled, for example Porter (2000) suggests that new groups of life evolved during this period, including the red algae and green algae, stramenopiles, ciliates, dinoflagellates, and testate amoeba. > The end of the period also saw the origin of heterotrophic plankton, which would feed on unicellular algae and prokaryotes, ending the bacterial dominance of the oceans. Even during catastrophic events, life persists in certain niches: deep sea life usually flourishes during massive extinctions because the marine snow becomes a blizzard; ducks survived the dinosaur extinction because rivers obtain bioavailable energy from gravity and erosion, not photosynthesis. So I suspect something like an "Mars vs Venus" cycle is necessary for the evolution of complex life. A highly predictable habitable planet might have cyanobacteria but not algae, since there wouldn't be any selective crises for mutated bacteria to adapt to. It would be awfully hard for a spectrometer to tell the difference between a planet full of bacteria and a pre-civilization planet full pf complex life. [1] https://en.wikipedia.org/wiki/Cryogenian https://en.wikipedia.org/wiki/Cryogenian
Slava_Propanei 3y ago
[dead]

boomboomsubban 3y ago

The process they described took millions of years. Yeah, we're probably in a somewhat rare in-between point. That "point" is still unimaginably long.

somenameforme 3y ago
Sediment cores show extreme temperature oscillations over far shorter time frames. This [1] is 5 million years of temperature reconstructions based on the Vostok ice cores. Keep in mind the scale, the difference between the peaks and valleys is 10 degrees celsius! But the really interesting thing is that that derived from this [2], which is Earth's temperature over the past 65 million years. Those previous extremes just blur, because now you're talking about a temperature difference of 20 degrees celcius, no ice on the planet, and giant beasts roaming in lush greenery. Greenery which was basically everywhere, even Antarctica! [3] ---- [1] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/media/File:Five_Myr_Climate_Change.png https://en.wikipedia.org/wiki/Geologic_temperature_record#/m... [2] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/media/File:65_Myr_Climate_Change.png https://en.wikipedia.org/wiki/Geologic_temperature_record#/m... [3] - https://en.wikipedia.org/wiki/Eocene#/media/File:Ypresian_Earth_50_mya.jpg https://en.wikipedia.org/wiki/Eocene#/media/File:Ypresian_Ea...

deepnet 3y ago

This balance is quite probably a very strong filter on the Drake equation. Climate and Biosphere is delicate with lots of tipping points and cascades to uninhabitable. A few billion years ago, the inner planets of the Sol system were capable of supporting abundant surface life - now only Terra.

pfdietz 3y ago

It could be the stability of Earth's systems is just an illusion created by observer selection. If it had not been within limits, we wouldn't be here. This places no constraint on how stable it will be in the future. Another part of the system that could be like that is the oxygen content of the atmosphere. The time constant for variation in O2 level is just a few million years (due to consumption of O2 by release of reducing gases and weathering of rocks to expose reduced materials like ferrous iron.) If it had ever dropped too much during the Phanerozoic higher life would have been wiped out. I don't believe any plausible feedback control mechanism has been discovered. In particular, fire involving plants (which couldn't have occurred before the evolution of large land plants) can be a positive feedback, as charcoal is very resistant to further oxidation and, when buried, represents a net increase in atmospheric oxygen. Maybe, if mankind explores the galaxy, we'll find all these formerly life bearing planets where stability failed.

BirAdam 3y ago
Stability is an illusion. It’s becoming increasingly evident that even small shifts in climate have triggered devastating events for humans, like the Bronze Age Collapse, plagues, and so on. Plus, there’s the whole end of the last glaciation that likely created the various flood myths and wiped out most of the megafauna.
- pfdietz 3y ago
  Arguably Venus and Mars were more habitable than Earth in the earlier solar system. Both fell off the stability wagon and now are dead worlds (with possible survival of deep underground life on Mars.)

nicklecompte 3y ago

Keep in mind that becoming an ice ball likely led to significantly increased biodiversity, via Wikipedia: > Since 2009, some researchers have argued that during the Cryogenian Period, potentially the oldest known fossils of sponges, and therefore animals, were formed. However, it is unclear whether these fossils actually belong to sponges, though the authors do not rule out the possibility of such fossils to represent proto-sponges or complex microbial precursors to sponge-grade organisms. The issue of whether or not biology was impacted by this event has not been settled, for example Porter (2000) suggests that new groups of life evolved during this period, including the red algae and green algae, stramenopiles, ciliates, dinoflagellates, and testate amoeba. > The end of the period also saw the origin of heterotrophic plankton, which would feed on unicellular algae and prokaryotes, ending the bacterial dominance of the oceans. Even during catastrophic events, life persists in certain niches: deep sea life usually flourishes during massive extinctions because the marine snow becomes a blizzard; ducks survived the dinosaur extinction because rivers obtain bioavailable energy from gravity and erosion, not photosynthesis. So I suspect something like an "Mars vs Venus" cycle is necessary for the evolution of complex life. A highly predictable habitable planet might have cyanobacteria but not algae, since there wouldn't be any selective crises for mutated bacteria to adapt to. It would be awfully hard for a spectrometer to tell the difference between a planet full of bacteria and a pre-civilization planet full pf complex life. [1] https://en.wikipedia.org/wiki/Cryogenian https://en.wikipedia.org/wiki/Cryogenian

Slava_Propanei 3y ago

[dead]