According to a recent study, published in the Journal Nature, archaeologists will increasingly have to rely on other techniques as emissions continue to alter the composition of carbon isotopes in air. The human-caused emissions have been attributed recurrently for its contribution to climate change and global warming.
Key observations
- Between 1952 and 1962, the testing of nuclear weapons released a spike of ‘bomb carbon’ that quickly doubled the amount of carbon-14 in the air. Since then, that carbon-14 has been slowly absorbed by living things and the ocean.
- At the same time, the burning of fossil fuels has been rapidly releasing CO2 that does not contain carbon-14.
- The carbon-14 ratio in modern materials is now the same as in those from pre-industrial times.
- And because fossil fuels are still being burnt, the proportion of carbon-14 in the air will lessen further, mimicking conditions even further in the past.
- As per the study, modern items now look like objects from the early twentieth century in terms of radiocarbon dating.
- The trend could soon make it difficult to tell if something is 1,000 years old or modern.
- The development also means that forensic scientists will no longer be able to use radiocarbon fingerprints to pinpoint the ages of materials such as ivory, antiques and wine.
About Carbon-dating technique
- Carbon-dating techniques rely on the fact that there are several isotopes of carbon in the air. Stable carbon-12 is the most common.
- But there is also a small amount of radioactive carbon-14, which is generated mainly when cosmic rays interact with the atmosphere.
- The proportion of carbon-14 varies naturally over time.
- Living things absorb both types of carbon. After they die, the relative amounts of the two isotopes start to change as the radioactive carbon-14 decays with a half-life of 5,700 years.
- By measuring how much carbon-14 is left in an object, researchers can date organic materials, such as wood, fabric or bone, that are up to about 55,000 years old.
- Typically, the smaller the ratio of carbon-14, the older the material.
