SUMMER SOLSTICE SOLAR-RADIATION, THE 100 KYR ICE-AGE CYCLE, AND THE NEXT ICE-AGE

Modeling studies suggest that the summer solstice solar radiation is m ore important than the caloric half-year solar radiation in producing glacial/interglacial cycles because it is more representative of the e nergy available to melt ice during the short melt season. Here it is s hown that the correlation between the summer solstice solar radiation and the rate of change of the oxygen isotope record is generally great er than that between the caloric half-year radiation and the rate of c hange of the oxygen isotope record. These results also suggest that th e sawtoothed nature of the 100 kyr cycle may be produced by periods of relatively slow changes in ice volume, punctuated by periods of rapid growth that are initiated at times of extremely low summer solstice r adiation; and that it is unlikely that an ice age will begin in the ne xt 70 kyr.