By measuring the ratio of the radio isotope to non-radioactive carbon, the amount of carbon-14 decay can be worked out, thereby giving an age for the specimen in question.
But that assumes that the amount of carbon-14 in the atmosphere was constant — any variation would speed up or slow down the clock.
Radiocarbon dating can easily establish that humans have been on the earth for over twenty thousand years, at least twice as long as creationists are willing to allow.
Therefore it should come as no surprise that creationists at the Institute for Creation Research (ICR) have been trying desperately to discredit this method for years.
Scientists across countless disciplines rely on it to date objects that are tens of thousands of years old. An analysis by Heather Graven, a climate-physics researcher at Imperial College London, finds that today's rate of fossil-fuel emissions is skewing the ratio of carbon that scientists use to determine an object's age.
Combustion of fossil fuels is “diluting the fraction of atmospheric carbon dioxide containing radiocarbon,” Graven told , the large amount of carbon dioxide in the atmosphere will make new organic material appear to be 1,000 years old based on today’s carbon-dating models.
(Carbon dating is already limited in scope because older artifacts have to be dated using other methods.
For instance, Lucy, the 3.2-million-year-old human ancestor, was dated by scientists who studied the volcanic flows and ashes in deposits where her bones were found.)“Given current emissions trends, fossil fuel emission-driven artificial ‘aging’ of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected,” Graven wrote.
By the year 2100, the atmosphere will have a radiocarbon age of 2,000 years old. If Graven's calculations are correct, carbon dating as we know it today will no longer be reliable by the year 2030.
Which means scientists won’t be able to use carbon dating to distinguish between new materials and artifacts that are hundreds or thousands of years old.
Two distinct sediment layers have formed in the lake every summer and winter over tens of thousands of years.
The researchers collected roughly 70-metre core samples from the lake and painstakingly counted the layers to come up with a direct record stretching back 52,000 years.
Since the 1940s, scientists have used carbon dating to determine the age of fossils, identify vintages of wine and whiskey, and explore other organic artifacts like wood and ivory.