Re-analysis of existing data sets shows that they are fully consistent with northern-insolation control of Ice-Age cycles, and do not provide strong support for alternate models invoking tropical or southern controls. The coldest time of the last 100ka in central Greenland was nearly synchronous with the minimum in summer insolation about 24ka BP (thousand years before 1950). Approximately one-third of the total Termination-I warming since then was achieved over the almost 10ka before the abrupt warming into the Bolling, which some workers have interpreted as the start of the warming. Southern warming as recorded in the Byrd Station, Antarctica ice-isotopic record lagged northern warming. CO2 rise was roughly synchronous with southern warming, methane rise may have been delayed a little as was sea-level rise, and the change in the isotopic composition of atmospheric oxygen was delayed significantly. The data for the extrema just before Termination II are consistent with occurrence of the same phasing as for Termination I, but with somewhat different progression of the two terminations once initiated, perhaps because of differences in the forcing.
All Science Journal Classification (ASJC) codes
- Global and Planetary Change
- Ecology, Evolution, Behavior and Systematics