Fossil fuel emissions have been blamed for global climate change and the melting of polar ice, but research published in the Proceedings of the National Academy of Sciences shows that they might also hamper our ability to determine exactly how old fossils or relics are.
According to BBC News, the authors report that the carbon dioxide produced by the burning of fossil fuels over the next century could make radiocarbon dating, the method used by scientists to precisely determine the age of a vast array of different artifacts, considerably less accurate.
“A wide array of scientific disciplines and industries use radiocarbon analyses; for example, it is used in dating of archaeological specimens and in forensic identification of human and wildlife tissues, including traded ivory,” the authors wrote. However, fossil fuel emissions include a type of carbon that, when released into the atmosphere, and confuse the dating process.
Potential lack of carbon-14 to blame
Radiocarbon dating measures carbon-14, a radioactive form of the element that is produced in the atmosphere and absorbed by plants through photosynthesis. Animals that eat plants ingest carbon-14 (also known as 14C), allowing scientists to determine the age of anything organic in nature by comparing 14C levels to the non-radioactive carbon content of a sample.
Over the next 100 years, however, the researchers predict that fossil fuels “will produce a large amount of CO2 with no 14C,” because all of the carbon-14 would have been lost over several million years of radioactive decay. Thus, newly produced organic material will appear to have aged or lost 14C through decay, thus potentially making fresh organic material produced in the year 2050 all but indistinguishable from samples that are 1,000 years older.
“As carbon-14 decays over time the fraction will decrease so that’s how we use it for dating,” study author Dr. Heather Graven of the Imperial College London Department of Physics and Grantham Institute 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.”
Emission levels over the next 100 years to determine strength of dilution effect
Dr. Graven’s research investigated the likely carbon emissions pathways over the next 100 years and found that increased in non-radioactive carbon could begin impacting radiocarbon dating by as early as the year 2020. In time, some current applications for 14C could completely stop being usable, while other applications of the technique would be strongly affected.
“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,” said Dr. Graven. “So if we just measure the fraction they’ll look like they have the same age for radiocarbon dating.”
“It really depends on how much emissions increase or decrease over the next century, in terms of how strong this dilution effect gets,” she told the BBC. “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.”
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