The level of bomb carbon was about 100% above normal levels between 19.
The level of bomb carbon in the northern hemisphere reached a peak in 1963, and in the southern hemisphere around 1965.
The carbon 14 produced reacts with oxygen atoms in the atmosphere to form carbon dioxide.
This carbon dioxide is no different from those produced by carbon 12 and carbon 13; hence, carbon dioxide with carbon 14 has the same fate as those produced with the other carbon isotopes.
By the 1990s, the carbon 14 level was only about 20% higher than the theoretical 1950 level as measured by the activity of the oxalic acid reference standard.
Bomb carbon is essentially an artificial injection of carbon 14.
Nuclear weapons testing brought about a reaction that simulated atmospheric production of carbon 14 in unnatural quantities.
Reidar Nydal and Knut Lovseth have made radiocarbon measurements in atmospheric carbon dioxide from the northern and southern hemispheres from 1962 to 1993.
The carbon 14 produced is what is known as bomb carbon or artificial radiocarbon.
According to literature, nuclear weapons testing in the 1950s and 1960s have nearly doubled the atmospheric carbon 14 content as measured in around 1965.
The change in global radiocarbon levels brought about by human activities necessitated the use of a reference standard for carbon 14 dating. National Bureau of Standards had been adopted as standard for radiocarbon dating.
Radiocarbon dating needed an organic material that was not contaminated with carbon 14 from fossil fuel burning or nuclear weapons testing. Its radiocarbon content was theoretically the same as a wood sample grown in AD 1950, the zero point of the radiocarbon timescale used in quoting carbon dating results.