In April 1986, Russia's nuclear power station at Chernobyl exploded,
killing 250 people and sending radioactive fallout around the world.
Less than two years later, as the graph indicates, scientists
detected Chernobyl radioactivity in snow at the South Pole—a
graphic reminder of how small our planet is. In cores from
Antarctica and Greenland, researchers have pinpointed the beginning
of atomic-bomb testing in the mid-1950s. They have also identified a
spike representing fallout from stepped-up atmospheric testing that
took place just prior to the 1963 Test Ban Treaty, which allowed for
underground tests only. In the years following 1965, by which time
some 90 countries had signed the treaty, Antarctic snow revealed a
sharp drop in radioactive fallout.Graph modified from: Dibb, J., Mayewski, P.A., Buck, C.F. and Drummey, S.M., 1990, Beta radiation from snow, Nature, 344, 6270, 25