Climate

Fossil Fuel Emissions Are About To Throw Carbon Dating All Out Of Whack

CREDIT: flickr/Jeffrey

Those concerned with climate change spend a lot of time arguing that it’s not just an environmental problem, but also an economic, human rights, national security, and even mental health issue. Now a new study has found that greenhouse gas emissions could impact a range of unlikely fields due to their effect on radiocarbon dating, a much-heralded scientific method used to determine the age of objects containing organic material.

The study, published Monday in the Proceedings of the National Academy of Sciences, found that emissions from fossil fuels are artificially raising the carbon age of the atmosphere, which makes objects today seem much older than they are when scrutinized by a radiocarbon dater. This change in the ability to date objects could impact measurements commonly taken in a broad range of endeavors, including archaeology, forgery detection, forensics, earth science, and physiology.

For instance, the study suggests that by 2050 — just 35 years from now — new clothes could have the same radiocarbon date as something worn during the Battle of Hastings in 1066.

We already knew fossil fuel emissions were messing with our future, but now they might be messing with our future’s history. This is happening because carbon dating measures the percentage of carbon-14 versus non-radioactive carbon (C) found in an object to determine how long it has been around. Fossil fuels like coal and oil have been around for so long — millions of years — that all of their carbon-14, which has a half life of 5,730 years, is already decayed and gone. A half life is the period of time that it takes half a sample to decay.

As fossil fuel emissions mix into the atmosphere, they mix up the atmosphere’s carbon-14 balance by flooding it with non-radioactive carbon.

The carbon-14 in the atmosphere is absorbed by plants through photosynthesis, and when animals consume the plants they ingest it. So carbon-14 is found in all organic matter and has been used to figure out the age of thousands of artifacts since it first came into popular use in the 1940s and ’50s. Things that can be carbon dated include wood, bone, leather, hair, pottery, iron, ice cores and a host of other objects. The Dead Sea Scrolls, Stonehenge, and Ötzi the Iceman, a famous 5,500 year old mummy, were all carbon dated.

This is not the first time in modern history that carbon-14 levels have shifted. After a decrease in concentration that coincided with the Industrial Revolution, nuclear weapons testing caused a sharp rise in the middle of the 20th Century. Since then, observations show carbon-14 levels have been dropping, and they are now approaching a pre-industrial ratio, according to the press release for the study.

Carbon dating has suffered from artificial manipulation due to human impacts since it was discovered; not only from fossil fuel burning and nuclear detonations, but also agricultural chemicals that contaminate dating. It is known to be a form of science with a large margin of error. The issue now is just how large that error could become over a short amount of time.

As Gizmag reports, this variability has made it so that anything within 300 years of 1950 is considered modern according to radiocarbon dating protocol. However, if this study is correct, that 300-year margin of error could exceed 2,000 years by the end of the century.

“If we are adding non-radioactive carbon and that’s what’s happening with fossil fuels, we get this dilution effect,” Heather D. Graven, a physicist at the Imperial College London and author of the study, told the BBC.

Graven said that at current rates of fossil fuel emissions, increases in non-radioactive carbon could start to impact carbon dating by 2020. She also said there is still time to curtail this effect.

“If we reduce emissions rapidly we might stay around a carbon age of 100 years in the atmosphere, but if we strongly increase emissions we could get to an age of 1,000 years by 2050 and around 2,000 years by 2100,” she said. “If we reduced fossil fuel emissions, it would be good news for radiocarbon dating.”

So, add carbon dating to the list of reasons to mitigate greenhouse gas emissions.