ABSTRACT
The tempo and therefore the character of geophysical change are also different. When a forcing mechanism alters the circulation of the atmosphere and oceans, the basic components therein are liable to reach their new equilibria at quite different rates. Take adjustments to a sharp alteration in the thermal ambience. The characteristic time for effective ‘equilibration’ is given as a million seconds (c. 11 days) for the free atmosphere or surface soil. For sea ice, it varies between days and centuries. For mountain glaciers, 300 years is typical. With the bigger ice lobes, one must think in terms of millennia.22 The same applies to the ocean deeps. In the middle of this last century, pioneering Swedish work on deep seabed cores showed that temperature trends in the bottom water of the equatorial Atlantic Ocean matched the secular variations at the surface, though with much smaller amplitudes and a delay of ‘less than’ a few thousand years.23
