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Can someone ELI5 me how a gas that occupies 400ppm (0.04%) of our atmosphere creates a massively scaled “heating blanket” around the entire Earth? More than “sc

Can someone ELI5 me how a gas that occupies 400ppm (0.04%) of our atmosphere creates a massively scaled “heating blanket” around the entire Earth? More than “scientists have determined”. What is the physical effect that enables the minuscule presence of an element to multiply to such effect.

aaomidi 3y ago
You’re thinking in absolute terms which is the problem in understanding it. Imagine you have a surface that reflected a unit X of heat back to its source. Now it does 2X. In the next few decades it’s going to do 3X. Does it make sense now? That X was enough to keep us warm. Now we’re facing with that amount increasing significantly.
yosito 3y ago
Think of it like a tiny pinch of a very spicy pepper in a big pot of soup. Even a little bit can have a big effect! The reason CO2 is like very spicy pepper is that it is very good at absorbing infrared radiation from the sun, and then re-emitting that energy as heat in the atmosphere.
treeman79 3y ago
Simple. If you don’t give me your vote and your money the world will end. Exact reason doesn’t matter. If cheap clean portable fusion was invented tomorrow, if would quickly be banned for one reason or another. People need to sell disasters, not solutions.
- polotics 3y ago
  Just Wow. Clothing yourself in counterfeit cynicism much? "People" don't sell disaster, how much disaster do you fill up at the pump? What proportion of your first world non sustainable lifestyle is spent on these sales of disaster you mentioned?
polotics 3y ago
The light coming down is in wavelengths that get through, the radiation on the way back is lower frequencies, infrared that CO2 intercepts. The sun is a massive fusion reactor there is a lot of energy coming. The effect is small, but compounds and CO2 is an oxide, very stable molecule that sticks around.
eof 3y ago
It’s not massive. It’s extremely tiny. It’s just that the system is very delicate and we are even tinier, so the effects from our perspective are large. (Think getting hit with a little 1/100000000th of earth mass meteor. The earth will barely react on galactic scale/ long term, but the momentary occupants will sure get a shock)
namaria 3y ago
The blanket is a bad metaphor. It's not a layer of CO2 that traps the heat. "Green house effect" molecules just tend to absorb infrared. https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/ https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-...
puetzk 3y ago
CO2 is opaque to many wavelengths ("colors") of infrared light. So when the surface would be cooling at night by radiating infrared light back to the darkness of space, CO2 blocks(and reabsorbs) this energy, warming the atmosphere. This effect is strongest in a band around 15μm wavelength. https://www.acs.org/climatescience/atmosphericwarming.html https://www.acs.org/climatescience/atmosphericwarming.html has a pretty good (though above ELI5) set of graphs and explanations of the chemistry involved.
photochemsyn 3y ago
Mostly what's going on is that infrared that would have escaped to space at about 12 km up in the atmosphere is now partially absorbed and re-radiated by the increased CO2 at this level. At these altitudes, the atmosphere is cold and dry so injecting more CO2 has a knock-on effect: https://history.aip.org/climate/co2.htm https://history.aip.org/climate/co2.htm > "Improved physics theory and precise laboratory measurements in the 1940s and after encouraged a new way of looking at the absorption. Scientists were especially struck to find that at low pressure and temperature, each band resolved into a cluster of sharply defined lines, like a picket fence, with gaps between the lines where radiation would get through.(24) As Hulburt and Callendar had claimed, the most important CO2 absorption lines did not lie exactly on top of water vapor lines. Instead of two overlapping bands, there were two sets of narrow lines with spaces for radiation to slip through. So even if water vapor in the lower layers of the atmosphere did entirely block any radiation that could have been absorbed by CO2, that would not keep the gas from making a difference in the rarified and frigid upper layers." However, this CO2 at 12km only accounts for about 1/3 of the warming - what happens is that the warming is amplified by more evaporation (due to increased warmth) which injects more water vapor into the atmosphere (from the oceans and land evaportation) and that's the other 2/3 of the effect more or less. It is a slow change, but steady. It's entirely possible that humans will be able to adapt to much of the change, assuming we stop pumping fossil CO2 into the atmosphere within the next few decades or so.
- CodeWriter23 3y ago
  “evaporation is a cooling process” is what they taught us in high school. Has that changed? Because it still works with swamp coolers.
  - friend_and_foe 3y ago
    It doesn't get rid of total heat in the system, only on the surface from which is has evaporated. That heat is still in the vapor. You're not getting rid of heat, you're transferring it from the surface to the air.
snowwrestler 3y ago
Most of the “greenhouse effect” is provided by water vapor, CO2 is indeed a small component of the effect by itself. CO2 is the point of concern because the carbon cycle is slow. Any CO2 we add will be there for many decades. So it’s like compound interest: a small change over time adds up to a noticeable effect. The water cycle is very short, extra water vapor rains out quickly. This explains the physics: https://en.m.wikipedia.org/wiki/Greenhouse_effect https://en.m.wikipedia.org/wiki/Greenhouse_effect
- tzs 3y ago
  > Any CO2 we add will be there for many decades Many centuries.
imtringued 3y ago
A 1.5 ° increase is a 0.5% increase in temperature if you measure the temperature in Kelvin. There is hardly any discrepancy in scale. A 12x multiplier is not that surprising once you consider that oxygen and nitrogen don't have a greenhouse effect and thus we are speaking of 0.04% out of 1% of gases that might have a greenhouse effect. Both the concentration and effect of CO2 are small but since human life has a limited temperature band, even a 1.5°C increase does matter. And so far I have just been applying some commonsense to your number comparison logic. I didn't even have to understand the basic mechanisms of how it works, just that there might be some effect.

aaomidi 3y ago

You’re thinking in absolute terms which is the problem in understanding it. Imagine you have a surface that reflected a unit X of heat back to its source. Now it does 2X. In the next few decades it’s going to do 3X. Does it make sense now? That X was enough to keep us warm. Now we’re facing with that amount increasing significantly.

yosito 3y ago

Think of it like a tiny pinch of a very spicy pepper in a big pot of soup. Even a little bit can have a big effect! The reason CO2 is like very spicy pepper is that it is very good at absorbing infrared radiation from the sun, and then re-emitting that energy as heat in the atmosphere.

treeman79 3y ago

Simple. If you don’t give me your vote and your money the world will end. Exact reason doesn’t matter. If cheap clean portable fusion was invented tomorrow, if would quickly be banned for one reason or another. People need to sell disasters, not solutions.

polotics 3y ago
Just Wow. Clothing yourself in counterfeit cynicism much? "People" don't sell disaster, how much disaster do you fill up at the pump? What proportion of your first world non sustainable lifestyle is spent on these sales of disaster you mentioned?

polotics 3y ago

The light coming down is in wavelengths that get through, the radiation on the way back is lower frequencies, infrared that CO2 intercepts. The sun is a massive fusion reactor there is a lot of energy coming. The effect is small, but compounds and CO2 is an oxide, very stable molecule that sticks around.

eof 3y ago

It’s not massive. It’s extremely tiny. It’s just that the system is very delicate and we are even tinier, so the effects from our perspective are large. (Think getting hit with a little 1/100000000th of earth mass meteor. The earth will barely react on galactic scale/ long term, but the momentary occupants will sure get a shock)

namaria 3y ago

The blanket is a bad metaphor. It's not a layer of CO2 that traps the heat. "Green house effect" molecules just tend to absorb infrared. https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/ https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-...

puetzk 3y ago

CO2 is opaque to many wavelengths ("colors") of infrared light. So when the surface would be cooling at night by radiating infrared light back to the darkness of space, CO2 blocks(and reabsorbs) this energy, warming the atmosphere. This effect is strongest in a band around 15μm wavelength. https://www.acs.org/climatescience/atmosphericwarming.html https://www.acs.org/climatescience/atmosphericwarming.html has a pretty good (though above ELI5) set of graphs and explanations of the chemistry involved.

photochemsyn 3y ago

Mostly what's going on is that infrared that would have escaped to space at about 12 km up in the atmosphere is now partially absorbed and re-radiated by the increased CO2 at this level. At these altitudes, the atmosphere is cold and dry so injecting more CO2 has a knock-on effect: https://history.aip.org/climate/co2.htm https://history.aip.org/climate/co2.htm > "Improved physics theory and precise laboratory measurements in the 1940s and after encouraged a new way of looking at the absorption. Scientists were especially struck to find that at low pressure and temperature, each band resolved into a cluster of sharply defined lines, like a picket fence, with gaps between the lines where radiation would get through.(24) As Hulburt and Callendar had claimed, the most important CO2 absorption lines did not lie exactly on top of water vapor lines. Instead of two overlapping bands, there were two sets of narrow lines with spaces for radiation to slip through. So even if water vapor in the lower layers of the atmosphere did entirely block any radiation that could have been absorbed by CO2, that would not keep the gas from making a difference in the rarified and frigid upper layers." However, this CO2 at 12km only accounts for about 1/3 of the warming - what happens is that the warming is amplified by more evaporation (due to increased warmth) which injects more water vapor into the atmosphere (from the oceans and land evaportation) and that's the other 2/3 of the effect more or less. It is a slow change, but steady. It's entirely possible that humans will be able to adapt to much of the change, assuming we stop pumping fossil CO2 into the atmosphere within the next few decades or so.

CodeWriter23 3y ago
“evaporation is a cooling process” is what they taught us in high school. Has that changed? Because it still works with swamp coolers.
- friend_and_foe 3y ago
  It doesn't get rid of total heat in the system, only on the surface from which is has evaporated. That heat is still in the vapor. You're not getting rid of heat, you're transferring it from the surface to the air.

snowwrestler 3y ago

Most of the “greenhouse effect” is provided by water vapor, CO2 is indeed a small component of the effect by itself. CO2 is the point of concern because the carbon cycle is slow. Any CO2 we add will be there for many decades. So it’s like compound interest: a small change over time adds up to a noticeable effect. The water cycle is very short, extra water vapor rains out quickly. This explains the physics: https://en.m.wikipedia.org/wiki/Greenhouse_effect https://en.m.wikipedia.org/wiki/Greenhouse_effect

tzs 3y ago
> Any CO2 we add will be there for many decades Many centuries.

imtringued 3y ago

A 1.5 ° increase is a 0.5% increase in temperature if you measure the temperature in Kelvin. There is hardly any discrepancy in scale. A 12x multiplier is not that surprising once you consider that oxygen and nitrogen don't have a greenhouse effect and thus we are speaking of 0.04% out of 1% of gases that might have a greenhouse effect. Both the concentration and effect of CO2 are small but since human life has a limited temperature band, even a 1.5°C increase does matter. And so far I have just been applying some commonsense to your number comparison logic. I didn't even have to understand the basic mechanisms of how it works, just that there might be some effect.