How much does carbon dioxide contribute to global warming?

On April 8, 2014 I posted this:

I’ve been a skeptic of human caused global warming since I first heard of it in the 1980s.  I just don’t think humans have the power to alter the climate.  I’ve been especially doubtful of the claim that CO2 in the atmosphere is a significant regulator of the earth’s climate.

UPDATE: Phd. geologist and Honorary Research Fellow at The University of Aberdeen Euan Mearns writes on Vostok and the 8000 year time lag that the 450,000 year earth history shown in the Vostok ice cores studied in their seminal paper on the Vostok Ice Core, Petit et al (1999), make an important observation on the lack of correlation between temperature and CO2 levels until at least 1,000 years after the onset of temperature change. [Vostok is the Russian Antarctic base 780 miles from the South Pole in the middle of the Antarctic continent] There is a much better correlation between temperature change and methane (CH4). The only conclusion possible from Vostok is that variations in CO2 and CH4 are both caused by global temperature change and freeze thaw cycles at high latitudes. These natural geochemical cycles makes it inevitable that CO2 and CH4 will eventually correlate with temperature, but it is temperature that drives CO2 and CH4, not the other way round. It is therefore totally invalid to use this relationship as evidence for CO2 forcing of climate, especially since during the onset of glaciations, there is no correlation at all.

Here is the remainder of my post from last April.

Carbon dioxide constitutes about 40 parts per 100,000 parts of the atmosphere, or about 0.04%.  It is estimated that in 1750 when the industrial revolution began CO2 constituted about 30 parts per 100,000, or 0.03%.  As of now it might be increasing at the rate of 1 part per 100,000 every 5 years.  Holding that at a constant rate it would take 3,000 years for human burning of carbon-based fuels to raise CO2 up to 1% of the atmosphere.  But let’s assume the rate might accelerate, so say it only takes 1,500 years.

Assume further that before 1,500 years in the future something entirely unpredictable will happen, some new scientific discovery will occur that enables humans to run automobiles on water and heat homes with stored solar power for months. Or something else presently undreamed of occurs. It’s ridiculous for us to think we can possibly know what the main source of energy will be that far in the future.  It’s enough to know that what we see today isn’t going to change within our lifetimes or that of the next few generations, and what is going to exist then is completely beyond our ability to fathom.  So, stop worrying and be happy.

Except something I heard recently could set all that on edge.  I listen to a weekly podcast called “Econ Talk” hosted by Russ Roberts of the Library of Economics and Liberty.  The March 24, 2014 episode featured a climate change debate between John Kristy of the University of Alabama and Kerry Emanuel of the Massachusetts Institute of Technology.  Kristy is a skeptic and Emanuel is a true believer in human caused climate change.  Emanuel gave an opening statement in which he made claims that, if true, would turn my understanding of the role of CO2 in the atmosphere on its head.  On my head, I guess.  Here is what he said:

Econ Talk:

In the middle of the 19th century, the gifted Irish physicist, John Tyndall, made a remarkable discovery using a laboratory apparatus–it was [?]–that is that all of the absorption of infrared radiation that takes place in our atmosphere is done by a tiny amount of gas that makes up less than 1% of the atmosphere. That was quite a shocking revelation at the time. And not long after that, the Swedish chemist, Svante Arrhenius, found out that the climate is heavily regulated by one of the greenhouse gases, carbon dioxide, whose mass represents four ten-thousands of our atmosphere–a tiny trace. And calculated that without that four ten-thousands part of our atmosphere that is carbon dioxide, the earth would be a snowball. We wouldn’t be here. We couldn’t survive. This is not in dispute, this finding of the scientific community. It was not made with supercomputers. It was made with pencil and paper, and it can be replicated today. If that tiny amount of greenhouse gas is what is making our planet habitable, then there would be no surprise that if we double or triple it, we are taking a risk with the climate system.

So, if Emanuel is correct we’ve known since the 19th Century that a tiny amount of carbon dioxide constituting less than 1% of the atmosphere is the main gas involved in the greenhouse effect.  It is what makes life on earth possible.  Otherwise the earth would be a ball of ice if it had water, or if not just a very cold desert without any climate at all.  This being so, even tiny increases in atmospheric CO2 by human burning of fossil fuels could indeed cause a significant amount of warming.  This would mean that the warming alarmists are right and skeptics like me are all wet.

I thought surely either Kristy or Russ Roberts would challenge this assertion by Emanuel, but that never happened. I decided I needed to find out all I could about this John Tyndall who supposedly made this discovery over a hundred years ago.

So I did.  Now I’m even more baffled by Kristy’s and Roberts’ failure to challenge Emanuel.  It appears that Emanuel’s claim is nonsense.  I read quite a bit on Johh Tyndall. He was indeed a great scientist who made several significant contributions to our understanding of the earth’s atmosphere and the properties of earth’s greenhouse gases.  But he never said that carbon dioxide was the main contributor to the greenhouse effect. In fact, he said just the opposite.  He said what I’ve always understood, that water vapor is the principal cause of the greenhouse effect, and that other atmospheric gases, such as carbon dioxide have only a small effect.

The following statement from Wikipedia’s page on John Tyndall is quoted with confidence because it fairly summarizes everything else I read.

Wikipedia on John Tyndall:

Tyndall explained the heat in the Earth’s atmosphere in terms of the capacities of the various gases in the air to absorb radiant heat, also known as infrared radiation. His measuring device, which used thermopile technology, is an early landmark in the history of absorption spectroscopy of gases.[7] He was the first to correctly measure the relative infrared absorptive powers of the gases nitrogen, oxygen, water vapour, carbon dioxide, ozone, methane, etc. (year 1859). He concluded that water vapour is the strongest absorber of radiant heat in the atmosphere and is the principal gas controlling air temperature. Absorption by the other gases is not negligible but relatively small. Prior to Tyndall it was widely surmised that the Earth’s atmosphere has a Greenhouse Effect, but he was the first to prove it. The proof was that water vapor strongly absorbed infrared radiation.[8] Relatedly, Tyndall in 1860 was first to demonstrate and quantify that visually transparent gases are infrared emitters.[9]

People (some, not many) who know me as a climate change skeptic have asked where I get the hubris to be so critical of University scientists with Phd’s. I’m not really critical of them, I just think there are a lot of them that either don’t know what they are talking about or are trying to protect government grants they have to study climate change. They don’t deserve to be trusted merely because the have a Phd. They also have political positions and government research grants to protect. See, Lying to Get Grants.

UPDATE: I was ready to agree that that CO2 is a greenhouse gas. Th Vostok paper casts doubt on that as an assumption because it suggests that rather than CO2 driving temperature change, it is temperature change that drives CO2 levels, with a substantial time lag.

Venus’s atmosphere is 97% CO2 and its constant surface temperature in 460 degrees Celsius. Multiply that by 9/5 plus 32 for Fahrenheit. Did CO2 make Venus hot, or did a hot venus make its CO2 level rise to is present concentration?  Vostok suggests the latter, but who knows for sure. Venus is too hot for life in any form we know of it to exist. Even If we believe that CO2 is part of earth’s greenhouse gas effect that is making it possible for us to be alive, the CO2 component of earth’s atmosphere is increasing at only about 1 part per 100,000 every 5 years. It will take at least 1,500 years, and possibly as much as 3,000 years for earth’s CO2 component to increase from the current 40 part per 100,000 to 100 parts per 100,000. That would be 1.0% instead of the current 0.40%. Still a lot less than Venus’ 97%.

The earth has lots more water vapor in its atmosphere, but it changes rapidly over time and is not the same in all regions. We know that water vapor has a powerful greenhouse effect, for which we must be very thankful. Even though CO2 is insignificant as a percentage of the atmosphere, the warming alarmists claim that just a small increase in CO2 can stimulate a large greenhouse effect of water vapor. Vostok turns that on its head, but assume they’re right. Thus they claim that a the small increase in CO2 since the beginning of the industrial revolution has been responsible for a 0.7 degree Celsius increase in global temperature. The measurements used to support this are questionable, and there has been no warming at all in the last 17 years. If that amount of warming were to occur in the next 250 years, it would be a good, not a bad thing.

The only conclusion is that the alarmists are totally wrong about CO2, or if they are right the net effect will be a benefit to life to life on earth and not a detriment. At least not until many thousands of years into the future, by which time earth herself will have had a say in the matter.

  • Jack Harvey

    Read this from the Heartland Institute. U.N. claims on climate change are just a bunch of hot air

    Rightfully points out how the ” scientists” that promote global warming have been bought off with grants and peer pressure. I am a scientist as I got a M.Sc in biology before med school. It is a travesty to call these politically motivated researchers scientists as the are only in search of the next grant and peer recognition – not true science

    • TeeJaw

      Exactly right. Penn State was so glad to get Michael Mann on its faculty because he’s a cash cow of government grants to study global warming.

  • Scottar

    It’s both political and what I call gravy train science. the progressive need a new tax source for their over the top social programs so taxing carbon would be another cash cow for them. Unlimited government need an unlimited cash source along with unlimited control.

    • TeeJaw

      The evidence against CO2 as the leading cause of climate change just keeps coming, making for desperation in the alarmist camp.

  • Euan,
    I’m a microbiologist who graduated from the Royal College of Science and Technology (now the Uni of Strathclyde ) just before you were born. Knowing about celestial cycles and the geological evidence of past ages episodes of global warming and cooling and the timing of such events by radioisotope dating techniques.
    I have always been sceptical of anthropogenic CO2 as a major cause of global warming. So much of the alarm has been caused by the belief that computer created models tell the truth.
    The Club of Rome’s 1975 predictions were based on a computer model and the only one it got right was that of human population growth !
    Gloom and disaster did not follow the plan but it still believes it can distil sunbeams out of cucumbers.

    Regards, Jimbro

    PS Would you like a couple of 1976 cartoons about the next ice age ?

    • TeeJaw

      Brilliant comment, Jimbro, thanks for posting. On the cartoons, yes Sir, send then along. Some scientists believe we are still in the tail end of the last ice age, but others think we might be heading into another cool period. It’s been a cool summer in Jackson Hole.

  • Daniel

    This entire text is interesting to me.

    • TeeJaw


  • For those interested in this subject please listen to Dr. Neil Frank on this subject 42 minute Video.

    Dr. Frank is retired Houston weatherman and Former Head of United States hurricane center

  • Just one correction on the numbers – co2 makes up .04%, not .4% of the atmosphere.

    • TeeJaw

      Right you are! Thanks! I’ve fixed it.

  • AM

    Teejaw – I dont think you are correct. Please read this :

    Water Vapor Confirmed as Major Player in Climate Change11.17.08

    Still from animation showing global distribution of atmospheric water vapor The distribution of atmospheric water vapor, a significant greenhouse gas, varies across the globe. During the summer and fall of 2005, this visualization shows that most vapor collects at tropical latitudes, particularly over south Asia, where monsoon thunderstorms swept the gas some 2 miles above the land.
    Credit: NASA
    > Watch video
    Water vapor is known to be Earth’s most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated more precisely than ever the heat-trapping effect of water in the air, validating the role of the gas as a critical component of climate change.

    Andrew Dessler and colleagues from Texas A&M University in College Station confirmed that the heat-amplifying effect of water vapor is potent enough to double the climate warming caused by increased levels of carbon dioxide in the atmosphere.

    With new observations, the scientists confirmed experimentally what existing climate models had anticipated theoretically. The research team used novel data from the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite to measure precisely the humidity throughout the lowest 10 miles of the atmosphere. That information was combined with global observations of shifts in temperature, allowing researchers to build a comprehensive picture of the interplay between water vapor, carbon dioxide, and other atmosphere-warming gases. The NASA-funded research was published recently in the American Geophysical Union’s Geophysical Research Letters.

    “Everyone agrees that if you add carbon dioxide to the atmosphere, then warming will result,” Dessler said. “So the real question is, how much warming?”

    The answer can be found by estimating the magnitude of water vapor feedback. Increasing water vapor leads to warmer temperatures, which causes more water vapor to be absorbed into the air. Warming and water absorption increase in a spiraling cycle.

    Graph showing that the energy trapped by water peaks near the equator Based on climate variations between 2003 and 2008, the energy trapped by water vapor is shown from southern to northern latitudes, peaking near the equator.
    Credit: Andrew Dessler
    > Larger image
    Water vapor feedback can also amplify the warming effect of other greenhouse gases, such that the warming brought about by increased carbon dioxide allows more water vapor to enter the atmosphere.

    “The difference in an atmosphere with a strong water vapor feedback and one with a weak feedback is enormous,” Dessler said.

    Climate models have estimated the strength of water vapor feedback, but until now the record of water vapor data was not sophisticated enough to provide a comprehensive view of at how water vapor responds to changes in Earth’s surface temperature. That’s because instruments on the ground and previous space-based could not measure water vapor at all altitudes in Earth’s troposphere — the layer of the atmosphere that extends from Earth’s surface to about 10 miles in altitude.

    AIRS is the first instrument to distinguish differences in the amount of water vapor at all altitudes within the troposphere. Using data from AIRS, the team observed how atmospheric water vapor reacted to shifts in surface temperatures between 2003 and 2008. By determining how humidity changed with surface temperature, the team could compute the average global strength of the water vapor feedback.

    “This new data set shows that as surface temperature increases, so does atmospheric humidity,” Dessler said. “Dumping greenhouse gases into the atmosphere makes the atmosphere more humid. And since water vapor is itself a greenhouse gas, the increase in humidity amplifies the warming from carbon dioxide.”

    Specifically, the team found that if Earth warms 1.8 degrees Fahrenheit, the associated increase in water vapor will trap an extra 2 Watts of energy per square meter (about 11 square feet).

    “That number may not sound like much, but add up all of that energy over the entire Earth surface and you find that water vapor is trapping a lot of energy,” Dessler said. “We now think the water vapor feedback is extraordinarily strong, capable of doubling the warming due to carbon dioxide alone.”

    Because the new precise observations agree with existing assessments of water vapor’s impact, researchers are more confident than ever in model predictions that Earth’s leading greenhouse gas will contribute to a temperature rise of a few degrees by the end of the century.

    “This study confirms that what was predicted by the models is really happening in the atmosphere,” said Eric Fetzer, an atmospheric scientist who works with AIRS data at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Water vapor is the big player in the atmosphere as far as climate is concerned.”

    Related Links:

    > Will Runaway Water Warm the World?
    > Atmospheric Infrared Sounder (AIRS) Web page

    Kathryn Hansen
    NASA’s Goddard Space Flight Center