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Carbon Isotopes Prove Humans Have Caused Global Warming

The earth is warming. But can we be sure that humans are the cause? Yes. The same way cycling officials were sure that biker Floyd Landis doped with synthetic testosterone while winning the 2006 Tour de France.

With Lance Armstrong retired and most of the other top riders expelled for illegal drug use, Landis had become one of the favourites. He was leading when in stage 16 he fell to eleventh place. Then, just as his chances of winning seemed dashed, Landis won the next stage going away and went on to ride the Champs-Élysées in the winner’s yellow jersey.

A few days later, Landis’s team announced he had failed a test for banned steroids. Landis appealed the ban, raised an estimated $1M for his defence, and wrote a 300-page book titled, “Positively False: the Real Story of how I won the Tour de France.”

After years of denial, in 2010 Landis reversed himself and admitted that from 2002 through 2006 he had used a grab-bag of banned substances and methods. Why did he finally have to give up his denial? Because the carbon isotope test proved beyond reasonable doubt that he had doped with synthetic testosterone.

Testosterone is mostly carbon. Synthetic testosterone is made entirely from plants, which have a different carbon isotope ratio than our environment overall. The carbon in Landis’s body had the distinctive plant ratio, proving beyond reasonable doubt that he had doped with synthetic testosterone.

So how do scientists use the method to confirm that humans are causing global warming?

Since 1800, CO2 in the earth’s atmosphere has risen 40% and because of the greenhouse effect, warmed the planet. The obvious source of the added carbon is the 330 billion tons of carbon that burning fossil fuels has added to the atmosphere since the Industrial Revolution. Yet global warming deniers deny this obvious fact. Well then, let’s prove it.

First, coal, oil, and natural gas also come from plants and also have the distinctive carbon isotope ratio of plants. As CO2 in the atmosphere has built up steadily, its isotopic composition has shifted just as steadily in the direction of plant carbon. That tells us the added carbon is coming from plants. But what kind of plants? That question we can also answer.

One carbon isotope, C14, is radioactive and dies away to undetectable levels in 50,000 years or so. Fossil fuels, being millions of years old, have no C14 left. Adding ancient carbon should have lowered the proportion of C14 in the atmosphere—and it has. For the last 50 years, as the amount of carbon in the atmosphere has increased, its C14 ratio has fallen steadily.

Just as the carbon isotopes prove that Landis doped his body, they prove beyond reasonable doubt that humans are doping the atmosphere with ancient plant carbon, carbon from fossil fuels.

Unlike people, isotopes do not lie.


By. Dr James Powell

James Lawrence Powell is the author of The Inquisition of Climate Science. Powell is also the executive director of the National Physical Science Consortium, a partnership among government agencies and laboratories, industry, and higher education dedicated to increasing the number of American citizens with graduate degrees in the physical sciences and related engineering fields. This article is cross-posted with permission with the Columbia University Press blog.

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  • Rational Debate on April 25 2012 said:
    Not so simple!!! C14 spiked with atmospheric atomic testing conducted since 1945 and has been declining since the atmospheric test ban. This effect is dominating any decline observed in C14.


    Sorry to burst your carbon bubble.
  • Jon Neufeld on April 25 2012 said:
    I don't know if anyone is 'denying' that humankind is increasing the concentration of atmospheric CO2. I do know that many people are skeptical of the contention that the anthropogenic increase in atmospheric CO2 is and/or will cause catastrophic changes in our climate. You have done nothing with regards to the second statement, but congratulations on utterly destroying the strawman in the first.
  • Bill Yarber on April 25 2012 said:
    Yes, the Earth has warmed over the past 160+ years since the end of the LIA. Yes, CO2 concentrations have increased during that period and the industrial revolution and burning of fossil fuels have contributed to some on the increased CO2 in our atmosphere.

    However, the primary sources of CO2 in our atmosphere are biological (decay & plant respiration) and outgasing by the oceans as they warm. You did not mention which isotope of Carbon these produce. Since they are organic sources, my guess is they are the same as fossil fuels.

    The real question is what part of the warming over the past 160+ years is due to natural variation and what, if any, is due to CO2. Since we've only warmed (from abnormally low levels) about 0.8C during the period when CO2 has increased 40%, CO2 plays only a trivial role, if at all. Millions of years ago, CO2 levels were between 2,000 & 7,000 ppm, or 5 to 18 times today's concentrations. We didn't have catastrophic warming then, so we won't have it now.

    Ice core analysis from Greenland and Antarctica show that CO2 concentration changes lag temperature changes. Therefore, we would expect CO2 to have risen (with or without our contributions) since the Earth has warmed from the LIA.

    Bottom line, it doesn't matter that our fossil fuel consumption is increasing CO2 levels. All that does is help the vegetation we depend on for food, shelter and oxygen recycling.

  • klem on April 26 2012 said:
    "Just as the carbon isotopes prove that Landis doped his body, they prove beyond reasonable doubt that humans are doping the atmosphere with ancient plant carbon, carbon from fossil fuels."

    Absolutely true, but all that this shows is humanity is adding CO2 to the atmosphere , it does nothing to prove your opening claim that "Carbon Isotopes Prove Humans Have Caused Global Warming".

    If merely adding CO2 is sufficient evidence for you, that is proof you are a staunch member of the Church of Climate Alarmism.
  • Rational Debate on April 26 2012 said:
    Not only is the C14 argument flawed due to nuclear testing once one looks at the actual data; there is every indication that the earth's temperature is cooling down again.

    One needs to look at the DATA to understand this and not listen to the shrill and well funded and paid warming promoters. No silly straw man arguments, analogies or ad hom attacks are required when one looks at data. But when the data doesn't support the warmers; the nasty debating tactics are all they really have left.

    For rational people - here's the latest data - arctic sea ice extent is back to the 1979 - 2000 average. How can that be if we are warming??

  • Mel Tisdale on April 29 2012 said:
    It does not matter whether humans are causing the current warming, or not. What matters is that the planet is warming, and unless it can be proven that this warming is going to slow down and reverse itself pretty soon, then we as a species are in for rough ride. The only sensible course of action is to combat climate change with all the strategies possible in case it is as bad as so many of the computer models tell us it is. If those models prove to be wrong then at least we will have a clean environment. If we do nothing and the models are right, future generations will never forgive us, and why should they? They will see the evidence of what we knew and what little we did. They will read comments like those above this one and some will maybe even try to get their hands on them to tell them face to face just how they feel about the issue.

    Yes, I am a member of the 'alarmist' club. And yes, I do have children who will suffer and so too will their children. I care about that and seek to influence opinion towards taking action to combat it. It is probably too late to take the climate back to a stable state, but every little helps.

    Reading the above comments, it only saddens me just how out of touch with reality the contributers are. While there is the slight possibility that climate change will not be too bad, is it really a good idea to take the risk? Just weigh up the evidence. We seem already to be beginning to experience in a small way what the computer models predict the changed climate will be like. Try mocking efforts to control climate change in front of those that have lost their homes due to floods, or have lost their livestock due to drought.

    Wake UP! The only people who will benefit are the fossil fuel exectutives who have put their shareholders before the needs of their own families. What awful people. I can only hope that their children will turn against them when they realise what their parents have done to them.

    If you have children, go to skepticalscience.com. There you will find answers to almost every question that you might have on the matter. Your children will thank you enormously if they can see that you actually care for their future.
  • John McKay on June 06 2012 said:
    Ok,, how bad can it get?.. Lets just input the 7000 ppm CO2 concentration that we know happened a few million years ago, and see what the model shows. It seems like the oceans will be deeper, and the planet warmer, and the storms more violent...and oh yes, New York Denmark Netherlands and most island nations will be under water. So what will that cost if it takes 100 years to happen? hmmm, real estate in New York gets cheaper?
    The good news here in northern canada, we will be able to grow bananas on the arctic circle..
  • Mike Mellor on July 06 2012 said:
    Mel Tisdale thinks that we should combat climate change just in case the consequences are "bad."

    In theology, this position is called "Pascal's Wager." Even if you can't prove the Christian God exists, you should act Christian (tithe, hate homosexuals, disbelieve in evolution etc) just in case you're wrong.

    As far as the computer models go, attaching the word "computer" to a claim does not make it infallible. In fact as a former IT professional I can tell you that to err is human but to really screw things up it takes a computer.

    Mel Tisdale, I'm one hundred per cent for combating pollution. Like you, I want to leave my children and grandchildren a better, cleaner planet. But I don't worship a God that is unlikely to exist, and given the total lack of solid evidence I'm not going to stress over global warming.

    (All above to be taken with a strong dose of LOL.)
  • Lindsay Haisley on July 15 2012 said:
    Particulate atmospheric polution offsets the heat-trapping effect of CO2, which is pretty established science. The widespread use of high-flying commercial jet aircraft puts enough reflective particulate matter into the high atmosphere to have a noticable effect on temperature. In the three days following 9/11 the entire US commercial aircraft fleet was grounded, and a 1 degree C rise in temperature, averaged over time and distance was observed. See http://www.pbs.org/wgbh/nova/transcripts/3310_sun.html
  • Mouse on October 03 2013 said:
    This is difficult to digest and fully understand. Diffficult to get good info too. I have read that we have higher CO2 leves now than in any time in the 600,000 years? Not sure who to believe. I do know that the fossil fuel industry has polluted the air, drinking water and land with abusive practices and will do anything including murderous wars to keep their profits flowing. So I am inclined to believe the scientific researchers more than people who are obviously fossil fuel advocates..
  • Kenneth Waggoner on January 19 2014 said:
    Is it not true that many plants will not use carbon 14 in photosynthesis, and carbon 12 will be used by all plants and would increase flora? In addition, carbon 14 is being found in petroleum it either caused by neutrinos, contamination or oil is not millions of years old, and not 50000 years old. It appears to me life would benefit from natural carbon, and warming would make more arable land available and allow for existing soil from being stripped of nutrients. Besides who needs cap and trade, wall street and financial tycoons run enough.
  • Dave on July 15 2014 said:
    The carbon released from volcanoes is from ancient subducted ocean bottom sediment which contains plenty of plant and animal remains; animals eat plants and would contain some of the original plant isotope ratios). There is also much CaCO3 in this ocean bottom sediment. I presume a significant amount of this CaCO3 would not have plant isotope ratios b/c much of it is inorganically precipitated. All would have lost C14. Are these volcanic carbon emissions isotopically distinguishable from burnt fossil fuel emissions? Perhaps using C13? Onward thru the fog!
  • Bill P on April 14 2016 said:
    The article focuses on C14 which is a trace element. The most abundant is C12 which is what is emitted when burning fossil fuels. C13 is a small percentage. Plants take in C12 for photosynthesis and release O2 and C12 is what is taken up by the oceans.

    Am I missing something?

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