The Little Ice Age in Context
The scientific possibilities of drilling into polar ice were suggested in 1954, and the first cores were extracted from the Greenland ice sheet in 1956. While polar ice sheets are particularly valuable for recording global atmospheric conditions, because the effects of local conditions are minimized, small icecaps at high altitudes in the low and mid latitudes can reveal regional variations. The isotopic composition of the oxygen in ice is related to the temperature of the precipitation at the time of condensation, more negative values corresponding to lower temperature, and experience has shown that it may be used as a proxy for temperature at the surface when the snow fell. The results from the Summit ice cores greatly increased interest in the Younger Dryas, the extent of its influence and more particularly whether or not it affected the whole globe.