  Brief (less than 100 years) rapid-increase anomalies in the Earth's
atmospheric radiocarbon production have previously been attributed to either
gamma photon radiation from supernovae or to cosmic ray particle radiation from
exceptionally large solar flares. Analysis of distances and ages of nearby
supernovae remnants, the probable gamma emissions, the predicted Earth incident
radiation, and the terrestrial radiocarbon record indicates that supernova
causation may be the case. Supernovae include Type Ia white dwarf explosions,
Type Ib, c, and II core collapse events, and some types of gamma burst objects.
All generate significant pulses of atmospheric radiocarbon depending on
distances. Surveys of supernova remnants offer a nearly complete accounting for
the past 50,000 years. There are 18 events less than or at 1.4 kilo-parsec
distance, and brief radiocarbon anomalies with appropriate sizes occurred for
each of the closest events. In calendar years before 1950, these are: Vela, 22
per mil del 14C at 12,760; S165, 20 per mil at 7431; Vela Junior, 13 per mil at
2765; HB9, 9 per mil at 5372; Boomerang, 11 per mil at 10,255; and Cygnus Loop
(per mil change not calculated) at 14,722. Although uncertainties remain large,
the agreements of prediction to observation support a possible causal
connection.
