Carbon Dating Will Soon be Unreliable Due to CO2 Emissions
Putting a definitive date on really old plant and animal remains is hard enough as it is. Now, researchers say accelerating CO2 levels in the atmosphere will soon make carbon dating unreliable.
The method of carbon dating puts a time of death on organic remains by comparing the levels of radioactive and nonradioactive carbon.
When the sun’s rays react with nitrogen in the atmosphere, a radioactive isotope of carbon called carbon-14 is created. This isotope is absorbed by plants, and further up the food chain by herbivores, omnivores and carnivores.
All organic matter accretes this radioactive isotope while alive; but once deceased, carbon-14 begins decaying. By comparing the ratio of radiocarbon levels in decaying matter to those in the atmosphere, researchers can determine how long a plant, animal or organic-based material has been dead.
But the burning of fossil fuels, manmade carbon emissions, are dramatically increasing the amount of nonradioactive carbon in the atmosphere, throwing off the consistent ratios that make the dating technique possible.
“As carbon-14 decays over time the fraction will decrease so that’s how we use it for dating,” Heather Graven, researcher at Imperial College London and author of a new study on the subject, told BBC News. “But we can also change this ratio of radioactive carbon to total carbon, if we are adding non-radioactive carbon and that’s what’s happening with fossil fuels, we get this dilution effect.”
Graven says by 2050, a new pair of jeans will have the same radiocarbon date as something 10,000 years old.
“If we did any current measurements on new products, they will end up having the same fraction of radiocarbon to total carbon as something that’s lost it over time due to decay,” Graven said.
It’s not the end of dating, as scientists have a few other techniques. But it may soon be the end of carbon dating, a method that revolutionized both archaeology and forensic science after it was developed in the 1940s.
“This finding has strong and as yet unrecognized implications for many applications of radiocarbon in various fields, and it implies that radiocarbon dating may no longer provide definitive ages for samples up to 2,000 years old,” researchers concluded.