Page 1 of 15 12311 ... LastLast
Results 1 to 10 of 150

Thread: Some basic, empirical evidence in favor of AGW

  1. #1
    Outer space potato man

    Join Date
    Feb 2010
    Last Seen
    Yesterday @ 10:17 PM
    Gender
    Lean
    Undisclosed
    Posts
    51,342

    Some basic, empirical evidence in favor of AGW

    First things first
    This post should not be construed in any way, shape, or form to be comprehensive. Climate research spans more than a century and is a product of the work of thousands of scientists in dozens of fields of study. A post on an internet forum cannot possibly address all of it. This post should also not be construed as definitive proof of anything. The purpose is to establish that there is, despite what skeptics tell you, a body of empirical evidence that points to Anthropogenic Global Warming. (AGW) Lastly, it should be made very clear that I, Deuce, am not a climatologist and should not be considered an "expert" on this subject. My qualifications, if you can call them that, are a BS in Aeronautics, an IQ that internet tests claim is somewhat above average, and a lot of personal curiosity about, and interest in, the subject that has lead me to waste an awful lot of time at work reading about this stuff. So, read on if you're interested in some of the science behind the theory. Also, don't tell my boss, ok?

    Some basic facts to establish
    We need to address some fundamental facts in order to act as a base for this discussion. Although you wouldn't know it from spending time at these forums, agreeing on a base set of reality is important to debate!

    • Mankind has caused an increase in Carbon Dioxide (CO2) levels in the atmosphere.

    One would think that this point doesn't need to even be mentioned. After all, we burn rather staggering amounts of various fossil fuels, all of which emit CO2 when burned. Some skeptics, however, dispute that this leads to higher CO2 in the atmosphere, or that it leads to significant change. The usual arguments are that nature emits far more CO2 than we do, or that it absorbs what we put into the atmosphere. (or both) The people who argue this are full of hot air. (drumbeat) Actually, I'll refer to this as a mistake, rather than making the assumption that they are deliberately misleading people.

    The reason this mistake is made is a lack of consideration for the other half of nature's carbon cycle. While nature does in fact emit a lot more CO2 than we do, (nearly 800 gigatons per year compared to our ~29) it also absorbs a metric assload every year as well. The net result (800Gt- 1 assload) is that nature actually acts as a net carbon sink. That is, nature pulls more carbon out of the air than it releases into the air.

    Thanks, nature! Say, where does all this carbon go? Ahh, plants you say. Every year when plants grow, they do so by absorbing the carbon from carbon dioxide and spitting out the oxygen. Which is also swell for us. Also, the ocean absorbs CO2 as well, there's a tremendous amount of CO2 dissolved into the ocean. (a more pronounced example of this can be found in any soda bottle that hasn't been open for too long. the moral of the story is, don't shake the ocean)



    As if the coffin needed an additional nail, we can also detect a difference between naturally-emitted CO2 and CO2 emitted by fossil fuels. While I don't have a great understanding of this research myself, the basics of it is that carbon has different isotopes that have a noticeable difference in ratio when comparing natural CO2 to fossil fuel CO2. C12 vs C13, or something to that effect.

    • Carbon Dioxide absorbs radiation in the long-wave infrared spectrum
    This is simple, unassailable physics. We've known this for more than a century, but more recently fine-tuned the wavelengths when the Air Force needed to work on heat-seeking missiles. (apparently, knowing the absorption characteristics of atmospheric gases in the infrared spectrum is useful when you're trying to hit a fighter plan moving five hundred miles per hour by using that same spectrum. who knew.) So why is this all important?

    As you can see, the incoming solar radiation is primarily in the shortwave infrared spectrum. (as well as the visible spectrum, which is very convenient seeing as how visible light is... well, how we see) This radiation passes through the atmosphere more or less freely and hits the surface. The earth heats up and emits that radiation back. (think like an electric stove or hot pavement) The outgoing radiation is in the longwave infrared spectrum, and as we see from that chart, this radiation gets absorbed by several atmospheric gases: CO2, O2/O3 (ozone), H2O (water vapor), as well as some not-pictured gases like CFCs and methane. Oh no! The radiation comes in, but not all of it gets out! The greenhouse effect, we're doomed! Actually, for the most part this is a good thing. Without this effect, the earth would be about 33 C colder than it is now. Giant, lifeless ball of ice. Good for snowmen, bad for humans.

    Ok, so why is THIS important? The fundamental fact is that CO2 is one of several greenhouse gases. It absorbs radiation that would otherwise have gone to space. This energy gets re-emitted in all directions, causing heating.

    Papers on laboratory measurements of CO2 absorption properties « AGW Observer
    A whole bunch of papers on the subject.

    On to the empirical evidence
    Phew, finally. So, we've got these theories about CO2 causing warming, but can we back that up with evidence? Why yes, we can! These days, it's actually quite easy. Remember that longwave infrared radiation that the earth radiates and CO2 absorbs? We can track that. What we monitor:
    1) Outgoing radiation across the spectrum, via satellites.
    2) Incoming radiation across the spectrum, via ground stations.
    3) Temperature, of course

    So, if the theory is that increases in greenhouse gases will cause the atmosphere to absorb more energy that would otherwise escape, causing heating, what can we expect to see?
    1) Outgoing radiation in the spectrum absorbed by CO2 to decrease, relative to sun's output.
    2) Incoming radiation in the spectrum absorbed by CO2 to increase, as some of this outgoing radiation is reflected back down to earth.
    3) The changes in these two to correspond to the increase in CO2 in the atmosphere.
    4) A rise in temperature

    Hey, what do you know? This is exactly what we see! Outgoing radiation in CO2's absorption spectrum has decreased, the same radiation coming to the surface has increased. Same energy goes in, less energy goes out. Physics 101 tells us that this will cause heating, and we see a warming earth as well!
    Papers on changes in OLR due to GHG’s « AGW Observer

    Changes in outgoing radiation showing a decrease in the spectrum absorbed by CO2 and other greenhouse gases.


    Increases in the radiation at the surface in those same wavelengths.

    And, of course, a rise in temperature.
    http://img715.imageshack.us/i/heatcontent.png
    http://img571.imageshack.us/i/figa2lrg.gif
    (this image from NASA GISS temperature data)
    (last two images removed because the forums are jerks and I can only use 5 pictures)

    Phew! That was a bit of work. I had typed up some more on the common skeptics' counter-arguments, but it got eaten by the computer and I don't feel like retyping it at this particular moment.

    Now, I know there are skeptics out there who will just handwave this entire post with "CANT TRUST THE SCIENTISTS," but those people might very well be beyond help. The hope is that there are people out there who are more open-minded while being skeptical, who perhaps just haven't taken the time to learn more about the science behind it all. Maybe they'll read this and go "hmm, maybe there's more to this than I thought. I'll go read more and learn things!"

    Hooray for learning.
    Last edited by Deuce; 07-15-10 at 03:37 PM.
    He touched her over her bra and underpants, she says, and guided her hand to touch him over his underwear
    Quote Originally Posted by Lutherf View Post
    We’ll say what? Something like “nothing happened” ... Yeah, we might say something like that.

  2. #2
    Lurker
    iangb's Avatar
    Join Date
    Dec 2009
    Location
    Birmingham, UK
    Last Seen
    03-03-17 @ 02:04 PM
    Gender
    Lean
    Independent
    Posts
    2,927
    Blog Entries
    1

    Re: Some basic, empirical evidence in favor of AGW

    For those who tl;dr, an incredibly brief summary.

    1. We've put lots of CO2 into the atmosphere, and it's sitting there accumulating. We know how much there is up there.
    2. CO2 is experimentally proven to absorb heat, but let UV light pass through. This means that incoming solar energy (mainly at the UV end of the spectrum) is let in, but outgoing/reflected solar energy (mainly at the IR end of the spectrum) is absorbed and retained. This has a warming effect.
    3. The Earth is warming at the rate which the theory (experimentally confirmed: see #2) says it should if CO2 is one of the driving influences.
    4. Therefore the CO2 that we have released is causing the warming effect.

    QED. See above for all of the experimental links and data.
    Last edited by iangb; 07-16-10 at 02:38 PM.
    The truth may be out there, but lies are in your head. ~Terry Pratchett

  3. #3
    Outer space potato man

    Join Date
    Feb 2010
    Last Seen
    Yesterday @ 10:17 PM
    Gender
    Lean
    Undisclosed
    Posts
    51,342

    Re: Some basic, empirical evidence in favor of AGW

    Quote Originally Posted by iangb View Post
    For those who tl;dr, an incredibly brief summary.

    1. We've put lots of CO2 into the atmosphere, and it's sitting there accumulating. We know how much there is up there.
    2. CO2 is experimentally proven to absorb heat, but let UV light pass through. This means that incoming solar energy (mainly at the UV end of the spectrum) is let in, but outgoing/reflected solar energy (mainly at the IR end of the spectrum) is absorbed and retained. This has a warming effect.
    3. The Earth is warming at the rate which the theory (experimentally confirmed: see #2) says it should if CO2 is one of the driving influences.
    4. Therefore the CO2 that we have released is causing the warming effect.

    QED. See above for all of the experimental links and data.
    Even MORE simplified:
    Incoming solar energy compared to outgoing energy shows that more and more energy is being absorbed in exactly the spectrum that CO2 and other man-made greenhouse gases cover, and in direct correlation to the increase in atmospheric concentrations of those gases. High school physics tells us this will warm the planet.
    He touched her over her bra and underpants, she says, and guided her hand to touch him over his underwear
    Quote Originally Posted by Lutherf View Post
    We’ll say what? Something like “nothing happened” ... Yeah, we might say something like that.

  4. #4
    User
    Join Date
    Aug 2010
    Location
    Aurora,IL
    Last Seen
    08-03-10 @ 10:17 PM
    Gender
    Lean
    Libertarian
    Posts
    1

    Re: Some basic, empirical evidence in favor of AGW

    JUST A COUPLE SIMPLE QUESTIONS. WE LIVE ON A PLANET 4.6 BILLION YEARS OLD AND WE HAVE STUDIED WEATHER AT BEST FOR 150 YEARS; CAN YOU HONESTLY CLAIM TO UNDERSTAND ALL THE CYCLES AND SCIENCE OF WEATHER? GLOBAL WARMING ENDED THE ICE AGES NOT ONCE BUT SEVERAL TIMES; MAN WAS NOT EVEN PRESENT FOR MOST OF THESE CYCLES, WHO DUNNIT? WE WOULD NOT BE HERE AS A SPECIES WITHOUT THE GLOBAL WARMING OF THE PAST. THE ATMOSPHERE IS TWENTY MILES THICK, A VAST OCEAN OF GASES; HOW CAN WE MAKE THESE DIRE CLAIMS BY MEASURING ONLY THE RISE IN SURFACE TEMPERATURES, I.E. tHE BOTTOM OF THE OCEAN? PAPPADAVE.

  5. #5
    Outer space potato man

    Join Date
    Feb 2010
    Last Seen
    Yesterday @ 10:17 PM
    Gender
    Lean
    Undisclosed
    Posts
    51,342

    Re: Some basic, empirical evidence in favor of AGW

    Quote Originally Posted by Pappadaver View Post
    JUST A COUPLE SIMPLE QUESTIONS. WE LIVE ON A PLANET 4.6 BILLION YEARS OLD AND WE HAVE STUDIED WEATHER AT BEST FOR 150 YEARS; CAN YOU HONESTLY CLAIM TO UNDERSTAND ALL THE CYCLES AND SCIENCE OF WEATHER? GLOBAL WARMING ENDED THE ICE AGES NOT ONCE BUT SEVERAL TIMES; MAN WAS NOT EVEN PRESENT FOR MOST OF THESE CYCLES, WHO DUNNIT? WE WOULD NOT BE HERE AS A SPECIES WITHOUT THE GLOBAL WARMING OF THE PAST. THE ATMOSPHERE IS TWENTY MILES THICK, A VAST OCEAN OF GASES; HOW CAN WE MAKE THESE DIRE CLAIMS BY MEASURING ONLY THE RISE IN SURFACE TEMPERATURES, I.E. tHE BOTTOM OF THE OCEAN? PAPPADAVE.
    Typing in all caps is considered poor etiquette when it comes to internet posting.

    You're making the very common and very fundamental error of assuming that an effect can only have a single cause. Temperature changed on earth without the presence of man, but that does not necessarily mean man is incapable of changing temperature. People got lung cancer before cigarrettes existed, does that mean cigarrettes are safe? There are multiple primary drivers of global average temperatures. We can observe and measure them. Some of the main drivers: The greenhouse effect, continental configuration, solar output, volcanic activity, and milkanovich cycles (regular "wobbles' in the earth's orbital mechanics). Over a mere 150 years, continents and orbital mechanics don't change enough to cause a temperature spike of this magnitude. The sun we can measure directly, we've been observing sunspot activity for more than a century and for the last 40 years we've been directly measuring solar output

    A couple things to point out:
    1) This thread is not comprehensive, there's a lot more evidence than what I just showed you.
    2) We measure temperature not just at the surface, but at various altitudes via weather ballons and also using satellites.
    3) The energy being absorbed by CO2 has to go somewhere, it's simple physics. If you want more proof that CO2 is a greenhouse gas, check out Venus. Despite being closer to the sun, Mercury is not as warm as Venus.
    He touched her over her bra and underpants, she says, and guided her hand to touch him over his underwear
    Quote Originally Posted by Lutherf View Post
    We’ll say what? Something like “nothing happened” ... Yeah, we might say something like that.

  6. #6
    Sage
    Renae's Avatar
    Join Date
    Aug 2007
    Location
    San Antonio Texas
    Last Seen
    10-23-17 @ 10:14 PM
    Gender
    Lean
    Undisclosed
    Posts
    38,972
    Blog Entries
    15

    Re: Some basic, empirical evidence in favor of AGW

    Did you email Algore for talking points again hun?
    Climate, changes. It takes a particularly uneducated population to buy into the idea that it's their fault climate is changing and further political solutions can fix it.



  7. #7
    Banned
    Join Date
    Jun 2008
    Location
    Canada
    Last Seen
    12-26-10 @ 06:57 PM
    Gender
    Lean
    Independent
    Posts
    8,083

    Re: Some basic, empirical evidence in favor of AGW

    Thanks Deuce for another informative post. I enjoy reading your logically-consistent deductions about global warming.

  8. #8
    Sage
    Renae's Avatar
    Join Date
    Aug 2007
    Location
    San Antonio Texas
    Last Seen
    10-23-17 @ 10:14 PM
    Gender
    Lean
    Undisclosed
    Posts
    38,972
    Blog Entries
    15

    Re: Some basic, empirical evidence in favor of AGW

    Quote Originally Posted by Orion View Post
    Thanks Deuce for another informative post. I enjoy reading your logically-consistent deductions about global warming.
    It's talking points, it's kool-aide for true believers.

    Do you know why no one posts counters anymore? It's NOT WORTH THE EFFORT! But we do read, and laugh. It's like a comedic relief moment.

    AGW is a political movement, not a scientific one.
    Climate, changes. It takes a particularly uneducated population to buy into the idea that it's their fault climate is changing and further political solutions can fix it.



  9. #9
    Sage
    Renae's Avatar
    Join Date
    Aug 2007
    Location
    San Antonio Texas
    Last Seen
    10-23-17 @ 10:14 PM
    Gender
    Lean
    Undisclosed
    Posts
    38,972
    Blog Entries
    15

    Re: Some basic, empirical evidence in favor of AGW

    Hey, about that CO2, increase, what's the yearly PPM increase again?
    Climate, changes. It takes a particularly uneducated population to buy into the idea that it's their fault climate is changing and further political solutions can fix it.



  10. #10
    Sage
    Dav's Avatar
    Join Date
    Mar 2009
    Location
    Virginia
    Last Seen
    04-16-16 @ 02:36 AM
    Gender
    Lean
    Libertarian - Right
    Posts
    5,539

    Re: Some basic, empirical evidence in favor of AGW

    Most of the OP I've already seen many times. What I didn't see was repudiation of the fact that, since CO2 makes up such a tiny portion of greenhouse gasses overall (95% of which is water vapor), humans activity accounts for less than half of 1% of greenhouse gasses in the atmosphere. Maybe there's a case to be made that this is all it takes, but I have yet to see that case be made.

    I don't doubt that human activity is causing the globe to get warmer... by somewhere between .001 and 1.5 degrees C. The question is how much within that scale.

Page 1 of 15 12311 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •