So here’s my basic physical reasoning about humans causing global warming. Carbon 14 has a half life of about 5700 years and after about 40,000 years it becomes useless for dating things. Fossil fuels are hundreds of millions of years old. All the C14 should basically be undetectable, so by measuring the ratio of carbon isotopes in the atmosphere over a period of a hundred years, we should be able to detect the clear signal that we are responsible for the increase in carbon. It’s not that simple.
Carbon 14 can be found in coal and oil. Some scientists think that it could be due to natural radioactive decay or organisms living at those depths. Though how the C14 would get into the organisms isn’t explained. So I’ll go for radioactive decay of uranium. It also depends on where the fossil fuels are gotten from. Some have very low proportions of carbon-14 as expected, others have more. However we should be able to determine the minimum and maximum ratios expected and compare them to the atmosphere ratios. Is the top of range still much lower than atmospheric C14? I suspect it would be. We might still be able to tell. Finally, another problem arises with the atmosphere.
Back in the 1950’s we started exploding atomic bombs in the atmosphere. This created a spike of C14. It has been decreasing since then. Prior to the 1950’s we did detect that C14 ratios were decreasing. The thing to do is to look at the ratios of carbon in ice cores and sediment cores. Although my physical reasoning is good there are a lot of other factors that need to be looked at, so though we know the rate at which carbon 14 decays we may not have enough data to use it as a reliable fingerprint.
Carbon 13 is another stable isotope of carbon. There is less of it. Most plants prefer plain old carbon 12 to carbon 13. Corn however will metabolize C13, so it’s signature in our food supply is unmistakable. We could even do isotopic analysis of our hair to determine how much corn is in our diet. It’s a lot. I’ve already written a post on carbon 13. There have been studies that have shown the ratios of C12 to C13 changes during periods of cooling and warming in sediment cores.
Basically, I wanted Carbon 14 to be the smoking gun. It could be but I need to do more research to answer that question. On the face of it it sure seems like it. Of course global warming deniers go to great lengths to protect their cherished beliefs the same way creationists continue ignoring the evidence of evolution. There are still debates within the scientific community over global warming. It’s influence on Hurricanes is hotly disputed, but the evidence is pointing in that direction. Of course, there are many lines of evidence (a.k.a. “smoking guns”) that point to humans as the culprit responsible for global warming, but some humans like global warming deniers are immensely resistant to reason and logic and evidence.