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.
Joe Romm is a Fellow at American Progress and is the editor of Climate Progress, which New York Times columnist Tom Friedman called "the indispensable… More
Comments
http://en.wikipedia.org/wiki/File:Radiocarbon_bomb_spike.svg
Sorry to burst your carbon bubble.
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.
Bill
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.
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??
http://wattsupwiththat.files.wordpress.com/2012/04/n_timeseries1.png
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.
The good news here in northern canada, we will be able to grow bananas on the arctic circle..
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.)
Am I missing something?