The fact that scientific methods like these, fail beyond a certain domain of approximation, doesn't make them redundant.
This raises questions about the accuracy of carbon dating for very old objects.Beck and colleagues tested slices of a half-metre long stalagmite that grew between 45 000 and 11 000 years ago in a cave in the Bahamas.The team speculates that a supernova shock wave could have produced a flurry of cosmic rays.“Weaker circulation of the oceans – which are the biggest reservoirs of carbon on Earth – would explain the excess of carbon-14”, David Richards, joint team leader, told Physics Web.Evidence from North Atlantic sediments suggests that the Earth’s magnetic field may have dipped around 40 thousand years ago, but this would still only account for – at best – half of the observed peak in carbon-14 concentrations.
Beck’s team concludes that either a jump in the cosmic ray flux or a fundamental change in the carbon cycle must have produced the sudden increase of carbon-14.
Scientists use carbon dating to determine when objects ceased to absorb carbon by measuring how much of the carbon-14 – which has a half-life of 5730 years – has decayed.
But Beck and colleagues believe that the ratio of stable and radioactive carbon in the atmosphere may have changed considerably over the last 50 thousand years.
Living organisms and some geological features absorb stable carbon-12 and radioactive carbon-14, which are present in the air in a well-known ratio.
This is part of the carbon cycle – the recirculation of carbon through the oceans, atmosphere, plants and animals.
Here, I explore the error levels of this dating method.