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I'm a little confused about how nuclear winter works esp. in relation to climate change, maybe someone here can enlighten me. The article states: "large colum

by darzu 5y ago

I'm a little confused about how nuclear winter works esp. in relation to climate change, maybe someone here can enlighten me. The article states: "large columns of smoke and soot rise up [...] to the stratosphere. There it [...] blocks the sun [...] The nuclear winter [...] is expected to lead to temperature declines of 20 or even 30 degrees Celsius (60–86° F)" So "smoke and soot" placed in the stratosphere lowers the earth's temperature, yet C02 in the atmosphere raises earth's temperature? Why? Follow up naive question: can we strategically place smoke in the stratosphere to counter global warming? What are the consequences of that?

chiefalchemist 5y ago
There's been discussion of trying to alter the atmosphere to lower the earth's temperature. In theory, I suppose, it's possible. The reality is, humans too often over-estimate their understanding and then muck X or Y up even more. Given that we're talking about a scale encompassing the whole planet and the future there of...well, you see it's risky.
SketchySeaBeast 5y ago
My understanding is that CO2 absorbs long-wavelength infrared energy and doesn't stop the rest of the radiation/light from hitting Earth's surface, while smoke and soot, being opaque, partially prevents the light from reaching the surface and reflects the energy back into space.
yed 5y ago
CO2 is transparent to visible light but not to infrared, so it allows sunlight to heat the surface of the earth but impedes its cooling. Smoke and soot is not transparent, so it blocks sunlight from heating the surface in the first place.
ip26 5y ago
Particles are reflective to incoming visible light, while CO2 is transparent to incoming visible light but opaque to infrared radiation (heat).
deleted 5y ago
[deleted]
ceejayoz 5y ago
> Follow up naive question: can we strategically place smoke in the stratosphere to counter global warming? What are the consequences of that? https://en.wikipedia.org/wiki/Solar_geoengineering https://en.wikipedia.org/wiki/Solar_geoengineering Neal Stephenson's latest book "Termination Shock" portrays such a program, and emphasizes some of the complexities; global mitigations tend to have very local effects at times.
shadowofneptune 5y ago
The soot particles make the color of that part of the planet into a lighter color. In planet science, this is known as 'albedo.' A lighter albedo increases the amount of solar rays which are reflected into space. There are proposals to use this to reduce warming, of varying seriousness. It's seen as a rather extreme measure though: https://www.bbc.com/future/article/20190220-how-artificially-brightened-clouds-could-stop-climate-change https://www.bbc.com/future/article/20190220-how-artificially... That all said, the degree of cooling predicted by nuclear theorists was overstated—not that overstating the destructiveness of nuclear weapons is so bad: https://www.nytimes.com/1990/01/23/science/nuclear-winter-theorists-pull-back.html https://www.nytimes.com/1990/01/23/science/nuclear-winter-th...
- murderfs 5y ago
  > That all said, the degree of cooling predicted by nuclear theorists was overstated—not that overstating the destructiveness of nuclear weapons is so bad Yeah, and even if it wasn't, the effects wouldn't be from nuclear weapons themselves, it would be from every single city burning down. Nuclear winter is pretty far down on the list of problems that a full blown nuclear war would cause.
landemva 5y ago
Particulates block incoming light. Crops fail. Malnutrition and disease. Year without a summer: https://scied.ucar.edu/learning-zone/how-climate-works/mount-tambora-and-year-without-summer https://scied.ucar.edu/learning-zone/how-climate-works/mount...
dplavery92 5y ago
It's worth mentioning that there has been some criticism[0] of the initial science behind the Nuclear Winter proposition. That said, smoke and soot can have a cooling effect on the Earth's temperature and CO2 (and other "greenhouse gasses") a warming effect because they absorb different wavelengths of light. The sun is a very hot (~5500K) blackbody that emits radiation in a broad spectrum, but that spectrum peaks in the visible. Some of that light is incident on Earth and warms it up. Earth also emits its own blackbody radiation, but it's much cooler (~300K), so it emits much less power over all and its spectrum peaks somewhere in the long infrared. The system is in equilibrium when the sun has heated the Earth enough that the total energy radiated away from Earth is equal to the fraction of the sun's radiation that is absorbed by Earth. Earth's atmosphere can change this equilibrium temperature by changing the fraction of incident energy that is absorbed by Earth, or changing its emissivity. Moreover, these changes can be wavelength dependent. Greenhouse gasses are gasses that are transparent in the visible spectrum but are reflective in the infrared, which allow in most of the sun's energy, but "trap" infrared energy that is being emitted by earth. Smoke and soot, by contrast, are very reflective in visible light (we can see them!) and so "block" much of the sun's energy from heating the Earth. [0]https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_debate https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_d...
antisthenes 5y ago
> I'm a little confused about how nuclear winter works esp. in relation to climate change, maybe someone here can enlighten me. It doesn't. The only study that seriously explored the possibility of nuclear winter and coined that term also showed that any cooling effects would be temporary and very likely insignificant to begin with. E.g. complete reversion to normal within 3-5 years, and continuation of global warming.

by darzu 5y ago

chiefalchemist 5y ago

There's been discussion of trying to alter the atmosphere to lower the earth's temperature. In theory, I suppose, it's possible. The reality is, humans too often over-estimate their understanding and then muck X or Y up even more. Given that we're talking about a scale encompassing the whole planet and the future there of...well, you see it's risky.

SketchySeaBeast 5y ago

My understanding is that CO2 absorbs long-wavelength infrared energy and doesn't stop the rest of the radiation/light from hitting Earth's surface, while smoke and soot, being opaque, partially prevents the light from reaching the surface and reflects the energy back into space.

yed 5y ago

CO2 is transparent to visible light but not to infrared, so it allows sunlight to heat the surface of the earth but impedes its cooling. Smoke and soot is not transparent, so it blocks sunlight from heating the surface in the first place.

ip26 5y ago

Particles are reflective to incoming visible light, while CO2 is transparent to incoming visible light but opaque to infrared radiation (heat).

deleted 5y ago

[deleted]

ceejayoz 5y ago

> Follow up naive question: can we strategically place smoke in the stratosphere to counter global warming? What are the consequences of that? https://en.wikipedia.org/wiki/Solar_geoengineering https://en.wikipedia.org/wiki/Solar_geoengineering Neal Stephenson's latest book "Termination Shock" portrays such a program, and emphasizes some of the complexities; global mitigations tend to have very local effects at times.

shadowofneptune 5y ago

The soot particles make the color of that part of the planet into a lighter color. In planet science, this is known as 'albedo.' A lighter albedo increases the amount of solar rays which are reflected into space. There are proposals to use this to reduce warming, of varying seriousness. It's seen as a rather extreme measure though: https://www.bbc.com/future/article/20190220-how-artificially-brightened-clouds-could-stop-climate-change https://www.bbc.com/future/article/20190220-how-artificially... That all said, the degree of cooling predicted by nuclear theorists was overstated—not that overstating the destructiveness of nuclear weapons is so bad: https://www.nytimes.com/1990/01/23/science/nuclear-winter-theorists-pull-back.html https://www.nytimes.com/1990/01/23/science/nuclear-winter-th...

murderfs 5y ago
> That all said, the degree of cooling predicted by nuclear theorists was overstated—not that overstating the destructiveness of nuclear weapons is so bad Yeah, and even if it wasn't, the effects wouldn't be from nuclear weapons themselves, it would be from every single city burning down. Nuclear winter is pretty far down on the list of problems that a full blown nuclear war would cause.

landemva 5y ago

Particulates block incoming light. Crops fail. Malnutrition and disease. Year without a summer: https://scied.ucar.edu/learning-zone/how-climate-works/mount-tambora-and-year-without-summer https://scied.ucar.edu/learning-zone/how-climate-works/mount...

dplavery92 5y ago

It's worth mentioning that there has been some criticism[0] of the initial science behind the Nuclear Winter proposition. That said, smoke and soot can have a cooling effect on the Earth's temperature and CO2 (and other "greenhouse gasses") a warming effect because they absorb different wavelengths of light. The sun is a very hot (~5500K) blackbody that emits radiation in a broad spectrum, but that spectrum peaks in the visible. Some of that light is incident on Earth and warms it up. Earth also emits its own blackbody radiation, but it's much cooler (~300K), so it emits much less power over all and its spectrum peaks somewhere in the long infrared. The system is in equilibrium when the sun has heated the Earth enough that the total energy radiated away from Earth is equal to the fraction of the sun's radiation that is absorbed by Earth. Earth's atmosphere can change this equilibrium temperature by changing the fraction of incident energy that is absorbed by Earth, or changing its emissivity. Moreover, these changes can be wavelength dependent. Greenhouse gasses are gasses that are transparent in the visible spectrum but are reflective in the infrared, which allow in most of the sun's energy, but "trap" infrared energy that is being emitted by earth. Smoke and soot, by contrast, are very reflective in visible light (we can see them!) and so "block" much of the sun's energy from heating the Earth. [0]https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_debate https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_d...

antisthenes 5y ago

> I'm a little confused about how nuclear winter works esp. in relation to climate change, maybe someone here can enlighten me. It doesn't. The only study that seriously explored the possibility of nuclear winter and coined that term also showed that any cooling effects would be temporary and very likely insignificant to begin with. E.g. complete reversion to normal within 3-5 years, and continuation of global warming.