Why is less than 0.04% CO2 important to climate change?

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Woody1

Registered Senior Member
I'm discussing climate with an Austrian horticulture professor. Our atmosphere is less than 400 ppm of CO2. How could that matter to the overall refractive index (link) which causes the greenhouse effect?

CO2 refractive index = 1.000449
Air refractive index = 1.000292

Supposedly the earth's CO2 concentration was 300 ppm at the start of the industrial revolution.

A change from 300 ppm to 400 ppm is as follows:

Air refractive index with 300 ppm CO2 = 1.0002920000
Air refractive index with 400 ppm CO2 = 1.00029201571

How can that matter?

Could changes in solar activity be more relevant to climate change?
 
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What?? Refraction has nothing to do with global warming.

CO2 absorbs radiation in the thermal band, preventing it from escaping the atmo.

And its effect is not proportional to its concentration; the effect rises rapidly with concentration

https://en.wikipedia.org/wiki/Greenhouse_gas

Gadzooks, I hope this professor isn't the one who thinks global warming is about refraction...
 
DaveC426913 said:
CO2 absorbs radiation in the thermal band, preventing it from escaping the atmo.
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I see that in some of the literature. At only 400 ppm that doesn't sound like much of a blanket. Also CO2 is heavier than air.

Reflection and refraction are both at work in the emission of radiation losses. The only way to lose heat is through radiation losses. This looks like a good science reference from Harvard: http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap7.html
 
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Woody1 said:
Reflection and refraction are both at work.
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If you can find a reputable reference that shows the refractive index of CO2 plays any part in heat retention, let alone global warming, I'll give you a sterling silver plaque of the queen.
 
spidergoat said:
Our atmosphere is very sensitive to small changes.

Absolutely not. Solar activity used to be one of the most important sources for climate change, but it's been dwarfed in recent times by carbon released by human activity.
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CO2 went from 300 ppm to almost 400 ppm. It still doesn't look like much though. That's from 0.03% to a little less than 0.04% of air in the atmosphere. Historical analysis doesn't seem to correlate CO2 concentration with the earth's temperature, prior to humans.

https://www.skepticalscience.com/co2-temperature-correlation.htm
 
Woody1 said:
CO2 went from 300 ppm to almost 400 ppm.
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260ppm to over 400ppm.
It still doesn't look like much though.
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Then let's run this experiment on you.

Let's increase the amount of As2O3 (a perfectly natural and naturally-occurring compound) in your body to 100ppm, far less than either the total amount of CO2 or even just the increase in CO2. That's about 100 milligrams per kilogram, which seems like nothing to me. Would you have an issue with such a tiny increase?
 
spidergoat said:
Why does the incredulity of an ignorant person matter?
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Why don't you ask yourself? Seriously. I was hoping for an intelligent point on a science forum about science, and this is the best you offer. How about some real data?

Not true. CO2 and temperature are very clearly linked, even before human times.
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yes true. Though CO2 contributes in some way, it is not the driving factor for global temperature change prior to human history. There was a time when the earth had 6000 ppm CO2 and it wasn't toast then.

Phanerozoic_CO2.gif



https://www.skepticalscience.com/co2-higher-in-past-intermediate.htm

from source: "The last time CO2 was similar to current levels was around 3 million years ago, during the Pliocene. Back then, CO2 levels remained at around 365 to 410 ppm for thousands of years. Arctic temperatures were 11 to 16°C warmer (Csank 2011). Global temperatures over this period is estimated to be 3 to 4°C warmer than pre-industrial temperatures. Sea levels were around 25 metres higher than current sea level (Dwyer 2008)."
 
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Woody1 said:
CO2 went from 300 ppm to almost 400 ppm. It still doesn't look like much though. That's from 0.03% to a little less than 0.04% of air in the atmosphere.
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This is ridiculous. If you have to troll, can't you at least make a bit of an effort?
 
DaveC426913 said:
If you can find a reputable reference that shows the refractive index of CO2 plays any part in heat retention, let alone global warming, I'll give you a sterling silver plaque of the queen.
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That was kind of the point I already made in the OP. CO2 contributes something, I agree, but it does not correlate all that well with the earth's history as I already provided a reference. Do you have a better one? I'm all ears.
 
Woody1 said:
Why don't you ask yourself? Where's your data?
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What's your objection? Appeal to low numbers? The smallness of a number has no correlation to it's effect in a natural system.

Woody1 said:
yes true. CO2 is not the driving factor. There was a time when the earth had 6000 ppm CO2 and it wasn't toast then.
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Sea levels were much higher, and the climate was much warmer. Humans didn't exist yet. Our climate has never had such high CO2 levels in all of human history. It's also changing at a faster rate than at any time in recorded history, so that's a problem too.

Look, no one is saying that all life on Earth will be wiped out. Some species will survive and eventually life will adapt to new conditions. But human caused global warming will be a serious problem for our civilization, for several centuries at least.
 
Woody1 said:
That was kind of the point I already made in the OP. CO2 contributes something, I agree, but it does not correlate all that well with the earth's history as I already provided a reference. Do you have a better one? I'm all ears.
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You deny science for political reasons and so have zero credibility on the issue.
 
Woody1 said:
yes true. Though CO2 contributes in some way, it is not the driving factor for global temperature change prior to human history. There was a time when the earth had 6000 ppm CO2 and it wasn't toast then.
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From your own link:

"When CO2 levels were higher in the past, solar levels were also lower. The combined effect of sun and CO2 matches well with climate."
 
spidergoat said:
What's your objection? Appeal to low numbers? The smallness of a number has no correlation to it's effect in a natural system.
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I agreed with Dave. Refraction isn't the cause. So let's move on to the real deal.


Sea levels were much higher, and the climate was much warmer. Humans didn't exist yet. Our climate has never had such high CO2 levels in all of human history. It's also changing at a faster rate than at any time in recorded history, so that's a problem too.
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Yes, CO2 is the highest in human history, but only about 5% of what it was during the Ordivician period. There was life on the planet then.

Look, no one is saying that all life on Earth will be wiped out. Some species will survive and eventually life will adapt to new conditions. But human caused global warming will be a serious problem for our civilization, for several centuries at least.
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Do you have someone that can tell us whether temperatures will rise over the next 200 years or not. If so, then perhaps Dave can give you his sterling silver plaque of the queen.
 
parmalee said:
Right. And you are posting in good faith, and not being willfully obtuse, yeah?
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If you were the bright light in the room, then you'd bring data. So where is it? Is it unfair for me to ask for your data on a science forum?
 
Woody1 said:
Do you have someone that can tell us whether temperatures will rise over the next 200 years or not.
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The IPCC. Over the next 100 years, temperatures will rise between 1.1 and 6.4 degrees C, depending on how much work we do to try to stop the warming.
 
Woody1 said:
I agreed with Dave. Refraction isn't the cause. So let's move on to the real deal.
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Don't agree with me. I made no claim that couldn't be found as easily in a wiki page or in a grade school textbook.

Why don't you just read up a little on the subject before starting to post conjectures about it? At the least it would better inform the questions you ask.

A little humility can go a long way.
 
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