Fossil fuel emissions will complicate radiocarbon dating, warns scientist

July 20, 2015

Fossil fuel emissions could soon make it impossible for radiocarbon dating to distinguish new materials from artefacts that are hundreds of years old.

Carbon released by burning is diluting radioactive carbon-14 and artificially raising the radiocarbon 'age' of the atmosphere, according to a paper published today (Monday 20 July 2015) in the journal PNAS.

Radiocarbon measurements have a range of uses, from analysing archaeological finds, to detecting fraudulent works of art, to identifying illegal ivory trading, to assessing the regeneration of brain cells in neurological patients.

The new study suggests that some of these current uses will be affected over this century, depending on how much increase or decrease.

"If we reduced fossil , it would be good news for radiocarbon dating," said the study's author, Dr Heather Graven from the Department of Physics and the Grantham Institute - Climate Change and Environment at Imperial College London.

Carbon-14 is a rare, but naturally occurring, radioactive type of carbon that decays over thousands of years.

Radiocarbon dating works by measuring how much the fraction of carbon-14 versus non-radioactive carbon in an object has changed and therefore how long the object has been around.

Fossil fuels like coal and oil are so old that they contain no carbon-14. When their emissions mix with the modern atmosphere, they flood it with non-radioactive carbon.

In radiocarbon dating terms this makes the atmosphere appear older, which is reflected in the tissues of plants taking in CO2 during photosynthesis, and their products such as cottons.

At the rate fossil fuel emissions are currently increasing, by 2050 a new T-shirt would have the same radiocarbon date as a robe worn by William the Conqueror a thousand years earlier.

If fossil fuel emissions were rapidly curbed, the new t-shirt would only have the same radiocarbon age as something 100 years old, according to the study.

The fraction of carbon-14 in the atmosphere decreased after the Industrial Revolution with the rise of . But in the 1950s and 60s, nuclear weapons testing caused a sharp increase. Since then atmospheric observations show the levels have been dropping, and are now close to the pre-industrial proportions.

The new study indicates that by 2020, the fraction of carbon-14 could drop to such an extent that will start to be affected.

"We can see from atmospheric observations that levels are steadily decreasing. How low they go depends on changes in our fossil fuel emissions," said Dr Graven.

Explore further: Greenhouse gas-caused warming felt in just months

More information: PNAS www.pnas.org/cgi/doi/10.1073/pnas.1504467112

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15 comments

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sstritt
not rated yet Jul 20, 2015
Even if true it would be easy to compensate for this.
Vietvet
5 / 5 (2) Jul 20, 2015
Even if true it would be easy to compensate for this.


How?
Returners
1 / 5 (3) Jul 20, 2015
Even if true it would be easy to compensate for this.


How?


William the Conqueror didn't have a Nike logo on his shoes.
Returners
1 / 5 (3) Jul 20, 2015
Also, since the time of Chernobyl and Fukushima, you could develop a baseline for the amount of Caesium in an organism and compare daughter products as a proxy, because Caesium has a relatively short half-life, that makes it perfect for dating something happening after these nuclear events that happened only a few decades or a few years ago.

See?

I just turned a different environmental disaster into a proxy dating mechanism, at least for dating things which are relatively young.
plaasjaapie
not rated yet Jul 20, 2015
Any rationale in a storm.
Steve 200mph Cruiz
5 / 5 (5) Jul 20, 2015
Returners,
That's not how carbon dating works.
Carbon 14 is created from nitrogen in the atmosphere getting hit by protons from the sun.
What makes carbon 14 dating useful is that over the detectable time frame of its half life, the nitrogen levels in our atmosphere have remained relatively constant, which in turn creates a constant stream of radioactive carbon which is then taken up by various chemical processes, as you are made from the world around you.

I don't think cesium has an analogous formation process and I don't know if any cesium isotope even has the same half life.
Steve 200mph Cruiz
5 / 5 (4) Jul 20, 2015
Also "analysing archaeological finds, to detecting fraudulent works of art, to identifying illegal ivory trading, to assessing the regeneration of brain cells in neurological patients."

That stuff is a little more deep than "Nike logos". There are some talented artists out there who dedicate all their time to making forgeries because their is more money in it if you can get away with it, and they are damn good at it.
FredJose
1 / 5 (4) Jul 21, 2015
Fossil fuels like coal and oil are so old that they contain no carbon-14.

This statement is not true.
Fossil fuels like coal and oil are PRESUMED to be so old that they are assumed to contain no carbon-14. Yet, when actually tested for carbon-14 by independent laboratories, all samples were shown to contain carbon-14.
You can be sure that the scientists doing this testing took all the usual precautions to exclude contamination.

Now, the implications of this whole article is that scientists will villify and exclude the use of carbon-14 dating on fossils like dinosaurs and other supposedly millions of years old creatures. This will then do away with the problem that currently raises its ugly head in that the latest research shows that all samples of dinosaur and other fossils(that were tested) contain carbon-14 in significant quantities. Carbon-14 shows YOUTH, not ANCIENT. So I would not be surprised that people are looking for an excuse to avoid doing carbon-14 dating.
FredJose
1 / 5 (3) Jul 21, 2015
Just a correction - there are sources of oil other than from plants - those samples will not necessarily contain carbon-14.
zz5555
5 / 5 (2) Jul 21, 2015
Fossil fuels like coal and oil are so old that they contain no carbon-14.

This statement is not true.
Fossil fuels like coal and oil are PRESUMED to be so old that they are assumed to contain no carbon-14. Yet, when actually tested for carbon-14 by independent laboratories, all samples were shown to contain carbon-14.
You can be sure that the scientists doing this testing took all the usual precautions to exclude contamination.

None of what you claim here appears to be true: http://ncse.com/c...4-dating (see the 3rd question).
Shootist
1 / 5 (3) Jul 21, 2015
Fossil fuel emissions will complicate radiocarbon dating, warns scientist


So, what?
an_engineer
4.2 / 5 (5) Jul 21, 2015
Oh fun, an article to bring out both the climate deniers AND the creationist nutjobs.
gkam
3.4 / 5 (5) Jul 21, 2015
I like the "So, what?" comment the best for illuminating the state of Denier education.
antigoracle
1 / 5 (2) Jul 21, 2015
Well, at least the AGW lies aren't getting old.
gkam
1 / 5 (2) Jul 22, 2015
Here's a story not in the PO set yet.

Paris (AFP) - France signalled a "breakthrough" Tuesday at 46-nation talks in Paris tasked with paving the way for a highly-anticipated climate rescue pact to be inked in December.
Ministers and top officials at an informal gathering reached consensus on several issues that have stymied the official negotiations for years, France's top climate negotiator Laurence Tubiana told journalists.

Crucially, they concurred there should be a regular, five-yearly review, once the agreement kicks in, of the collective effort to curb planet-warming greenhouse gases.

"This is a breakthrough," said Tubiana. "That was not obvious to get."
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Poco a poco, . . we can save ourselves.

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