Scientists are concerned that fossil fuel emissions could be interfering with radiocarbon dating, making it more difficult to determine the age of ancient artifacts.

Carbon released by fossil fuels is diluting radioactive carbon-14, which is causing an increase of the "age" of the atmosphere, Imperial College London reported. Radiocarbon dating has a variety of uses, including analyzing artifacts, detecting illegal ivory, and revealing fraudulent works of art. Researchers are worried the emission of fossil fuels will interfere with these activities.

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

Radiocarbon dating works by measuring how much the fraction of carbon-14 versus non-radioactive carbon has changed in an object to determine its age. Carbon-14 slowly decays over time, and fossil fuels are so old that generally none is left. When these emissions mix with the atmosphere they create more non-radioactive carbon, making it appear older.

At the current rate of emissions, by 2050 a T-shirt worn today would have the same radiocarbon date as a robe worn by William the Conqueror a thousand years ago. If emissions are dramatically curbed, the T-shirt would only be dated at about 100 years old.

Researchers have determined the rate of fossil fuel emissions are on the decline, and have almost reached pre-industrial proportions. The study indicates that by 2020, the fraction of carbon-14 could fall to levels that would not have an effect on radiocarbon dating.

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

The findings were published in a recent edition of the journal Proceedings of the National Academy of Sciences.