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Author Topic: How can a small change in CO2 make a large change in climate?  (Read 4188 times)

Imogen Game

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Imogen Game  asked the Naked Scientists:
   
Dear The Naked Scientists,
 
I'd like to start by saying that I'm a huge fan of your show - I listen to literally every one of your podcast feeds and have done for a few years now.

I started listening to you guys when I was still in high school and you gave me lots of interesting anecdotes about all the latest science with which I regularly baffled my family and friends, who thought me extremely nerdy!

You guys make science so accessible - I regularly attempt to navigate public science journals and get lost in jargon and things I don't understand!
 
I have something that's been puzzling me for some time now, and I was wondering if you could give me your opinions on it. I am a massive climate skeptic - I find it really hard to believe that anthropogenic CO2 emissions could possibly have the kind of impact many mainstream scientists claim it does.
 
So this is my question for you:   If CO2 comprises 0.038% of the atmosphere, and only 3% of that is from anthropogenic sources, how can the tiny incremental increase in atmospheric composition that we've caused over time, really create substantial temperature change? Why is the evidence for sunspot activity not cited more often as a cause of recent climatic changes? Surely the impact of sunspots would vastly outweigh the tiny increase in the greenhouse affect? I would love to hear your explanations for this - it would be really helpful to me in my grappling!
 
Thanks very much! :-)
 
Imogen Game (Sydney, Australia)

What do you think?
« Last Edit: 27/03/2011 08:30:03 by _system »


 

Offline CliffordK

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How can a small change in CO2 make a large change in climate?
« Reply #1 on: 30/03/2011 18:22:17 »
So this is my question for you:   If CO2 comprises 0.038% of the atmosphere, and only 3% of that is from anthropogenic sources,
You have your numbers off a little bit...
CO2 comprises about 0.038% of the atmosphere.

But, the anthropogenic component is increasing from about 0.028% to about 0.038%, or about 30%.

The significance of the carbon dioxide is still being debated.  However, at certain IR frequencies, even the 0.038% CO2 is sufficient to absorb 100% of the outgoing IR light irradiation.  So, increasing the concentration of CO2 lowers the elevation at which this absorption occurs, as well as increasing the number of times the light is absorbed, and radiated on its outward path.

Certainly solar irradiation is also important, and one of the major complaints about the current anthropogenic global warming theories is that they seem to base too little on natural climate cycles.
 

Offline yor_on

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How can a small change in CO2 make a large change in climate?
« Reply #2 on: 03/04/2011 04:23:57 »

 

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