A Plunge In Incoming Sunlight May Have Triggered 'Snowball Earths' (phys.org) 53
Jennifer Chu writes via Phys.Org: At least twice in Earth's history, nearly the entire planet was encased in a sheet of snow and ice. These dramatic "Snowball Earth" events occurred in quick succession, somewhere around 700 million years ago, and evidence suggests that the consecutive global ice ages set the stage for the subsequent explosion of complex, multicellular life on Earth. Scientists have considered multiple scenarios for what may have tipped the planet into each ice age. While no single driving process has been identified, it's assumed that whatever triggered the temporary freeze-overs must have done so in a way that pushed the planet past a critical threshold, such as reducing incoming sunlight or atmospheric carbon dioxide to levels low enough to set off a global expansion of ice.
But MIT scientists now say that Snowball Earths were likely the product of "rate-induced glaciations." That is, they found the Earth can be tipped into a global ice age when the level of solar radiation it receives changes quickly over a geologically short period of time. The amount of solar radiation doesn't have to drop to a particular threshold point; as long as the decrease in incoming sunlight occurs faster than a critical rate, a temporary glaciation, or Snowball Earth, will follow. These findings, published in the Proceedings of the Royal Society A, suggest that whatever triggered the Earth's ice ages most likely involved processes that quickly reduced the amount of solar radiation coming to the surface, such as widespread volcanic eruptions or biologically induced cloud formation that could have significantly blocked out the sun's rays.
But MIT scientists now say that Snowball Earths were likely the product of "rate-induced glaciations." That is, they found the Earth can be tipped into a global ice age when the level of solar radiation it receives changes quickly over a geologically short period of time. The amount of solar radiation doesn't have to drop to a particular threshold point; as long as the decrease in incoming sunlight occurs faster than a critical rate, a temporary glaciation, or Snowball Earth, will follow. These findings, published in the Proceedings of the Royal Society A, suggest that whatever triggered the Earth's ice ages most likely involved processes that quickly reduced the amount of solar radiation coming to the surface, such as widespread volcanic eruptions or biologically induced cloud formation that could have significantly blocked out the sun's rays.
may day may day (Score:1)
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There's no "may" about it.
The ONLY thing that can possible cause a change in The Earth's temperature is the amount of sunlight reaching it.
(...and the only thing that can affect that is the Earth's atmosphere, hence global warming due to increased CO2)
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Joce640k misspoke:
There's no "may" about it.
The ONLY thing that can possible cause a change in The Earth's temperature is the amount of sunlight reaching it.
(...and the only thing that can affect that is the Earth's atmosphere, hence global warming due to increased CO2)
Er ... no. Not at all.
In the case of sudden, global glaciation events, every instance for which a direct cause has been established thus far has turned out to be the result of a major bolide impact. You may, for instance, be familiar with the K-T event, in which a nickle-iron asteroid struck what is now the Gulf of Mexico, just offshore from the Yucatan Peninsula, creating first a worldwide firestorm, followed immediately by an ice age (caused by suspended smoke and dust), which caused mos
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Joce640k misspoke:
The ONLY thing that can possible cause a change in The Earth's temperature is the amount of sunlight reaching it.
(...and the only thing that can affect that is the Earth's atmosphere
In the case of sudden, global glaciation events, every instance for which a direct cause has been established thus far has turned out to be the result of a major bolide impact. You may, for instance, be familiar with the K-T event, in which a nickle-iron asteroid struck what is now the Gulf of Mexico, just offshore from the Yucatan Peninsula, creating first a worldwide firestorm, followed immediately by an ice age (caused by suspended smoke and dust),
I think you're both right to a degree (pun intended). "Smoke and dust" suspended in the atmosphere, thereby limiting the amount of sunlight that reaches the Earth, but I think he did misspeak on the CO2 aspect, that doesn't affect sunlight at all.
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I think you're both right to a degree (pun intended). "Smoke and dust" suspended in the atmosphere, thereby limiting the amount of sunlight that reaches the Earth, but I think he did misspeak on the CO2 aspect, that doesn't affect sunlight at all.
The heat of the greenhouse effect comes from sunlight.
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I think you're both right to a degree (pun intended). "Smoke and dust" suspended in the atmosphere, thereby limiting the amount of sunlight that reaches the Earth, but I think he did misspeak on the CO2 aspect, that doesn't affect sunlight at all.
The heat of the greenhouse effect comes from sunlight.
And the severity of that 'greenhouse effect' depends on reflection, heat retention and atmospheric composition. Fluctuations in the earth's orbit also cause temperature fluctuations. Nothing is ever true/false binary choice simple in climate science.
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Er ... no. Not at all.
In the case of sudden, global glaciation events, every instance for which a direct cause has been established thus far has turned out to be the result of a major bolide impact. You may, for instance, be familiar with the K-T event, in which a nickle-iron asteroid struck what is now the Gulf of Mexico, just offshore from the Yucatan Peninsula, creating first a worldwide firestorm, followed immediately by an ice age (caused by suspended smoke and dust),
"caused by suspended smoke and dust", ie. less sunlight.
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The ONLY thing that can possible cause a change in The Earth's temperature is the amount of sunlight reaching it.
You mean besides the amount of near-infrared radiation leaving it?
(...and the only thing that can affect that is the Earth's atmosphere, hence global warming due to increased CO2)
Yeah, increased CO2 is about the greenhouse effect, which has to do with how much energy is retained, not how much energy arrives. HTH, HAND
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...Yes sunlight is definitely the main input energy. But it's not the only one - you can also add thermal energy in other ways. Exothermic chemical reactions, fission/fusion and friction heating from meteors converting kinetic energy to thermal energy being just a few examples. So we can increase the amount of energy entering the system.
These numbers are so incredibly small compared to the 173,000 terawatts of incoming solar radiation that the original poster is correct: they don't affect the temperature.
The atmosphere, however (as you point out) is not trivial.
Wrong atmospheric threat (Score:2)
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For this, climate change isn’t the threat, the supervolcano under Yellowstone is.
It's the geeky thing to worry about, but all the actual scientists who study is say it's not likely to go off any time soon.
https://www.express.co.uk/news... [express.co.uk]
https://blogs.scientificameric... [scientificamerican.com]
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Nobody is talking about the sun suddenly increasing or decreasing its output. The article is talking about the amount of radiation from the sun that reaches the Earth's surface.
That can be altered by the atmosphere, or by interplanetary dust clouds.
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Sorry. I mean interstellar dust clouds. Right now, our solar system is travelling through something known as the "local bubble." https://en.wikipedia.org/wiki/... [wikipedia.org]
It is a relatively sparse region of interstellar dust. There are also regions with much more dust, and when we travel through those regions, the dust reduces the amount of sunlight hitting the planet.
Again, sorry for the confusion. Hope this clears up what I was actually referring to.
Here's a scientific paper backing up what I said. (Score:2)
I suggest you may be the one lacking education: https://agupubs.onlinelibrary.... [wiley.com].
4. Conclusions
[17] Here, we demonstrated that an encounter of Earth with an average density GMC (330–103 H atoms/cm3), would produce a significant climate impact causing moderate (iceline at 50–60 latitude) glaciations. At least 2 times in the last 2 Gyr of the Earth's history, the solar system passed through GMCs with densities >2.2 × 103 atoms/cm3. Such encounters would result in more than 9.3 W/m2 change
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So, no paper to cite? We're done. Buh bye, and thanks for playing!
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Tell me something, is your username SirAstral? I'm guessing it is.
Fuck yes you can cite a paper that shows that GMC could not cause climate change. If such a paper existed. Which it doesn't.
You could also try to refute the arguments in the paper, from first principals and evidence you yourself have collected. But you have none.
What a failure you are. I revel in your humiliation here. Please keep going, this feeling of supremacy is so fucking good! Dunking on ignorant assholes like you gives me gratification
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You've still got nothing? Sad.
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That's because you're not bright enough to understand what is laboriously being explained to you over and over. Probably the same reason you post AC.
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You mean that climate change is a hoax perpetrated by tens of thousands of greedy scientists, or that it has only one cause, or that it's not human-caused? Yeah, the Big Lie Technique works really well on stupid people. For the minority of us able to comprehend that the universe is complicated and able to understand the analysis of the professionals working in the dozen or so fields affected it doesn't work so well. When trying to explain complex issues to the willfully ignorant we quickly run out of one
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Our founders paid the cost and took the risk by overthrowing their previous government through force of arms. We share that risk by enforcing decis
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The US Constitution was an experiment, a type of representational government structure that had never been tried before. I doubt that any of them ever expected that it would last for almost two and a half centuries and be enshrined as a religious artifact. That it's functioned as well as it has for as long as it has is amazing, but nothing says that it's the best possible system. Over half of the people eligible to vote didn't even bother to do so in 2018, a very large percentage of those who did just vo
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Only if your time and effort are worth next to nothing.
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This one of the only places on the internet where autists argue with each other over what color the sky is. Lots of supposedly smart people who think they know more than most.
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only if we print it all out on paper and feed it to our wood burning stoves.
shocked face (Score:2)
the earth suddenly got cold because there was suddenly less sunlight. hope these" scientists" are making more than my grocery bagger.
Dust Cloud (Score:2)
I'm wondering if a galactic dust cloud could be dense enough to block that amount of light, and whether enough dust would have fallen into the atmosphere to be detectable in rocks of the time. There aren't any near us now, but the Sun moves around a lot in 700 million years and there are a few clouds in our general neighborhood.
Global Dimming (Score:2)
Dropping a large will do the job (Score:2)
For an extreme example, if Jupiter were to drop onto the Sun, it would take about 16-17 years of darkness to go back to original sunlight levels. (At least according to the calculations here: https://www.quora.com/What-wou... [quora.com] ).
So, even if the object is not as massive as Jupiter, a sufficiently large one could cool the Sun down rapidly.
Just another way the Universe can introduce "Everybody Dies" scenario.