Interglacials

Figure 2a. Carbon dioxide concentrations in the atmosphere have varied over the glacial cycles of the earth s history, with high vjues at of around 300 during the interglacial period approximately 130,000 years ago...

CO2 is higher in interglacial times and lower in ice ages, indicating significant differences in photosynthesis between these two climatic states. 

Martin, J. H. (1990). Glacial-interglacial CO2 change The iron hypothesis. Paleoceanography 5,1-13. 

There may also be natural fluctuations within this cycle that occur over time scales ranging from thousands of years (glacial-interglacial) to millions of years (Follmi, 1996). Overall, the... 

Eccentricity variations change the average Earth-sun distance such that annual insolation changes by approximately 0.2%, or 0.5 W/m at the Earth s surface (Crowley and North, 1991). This is small compared to the 10% seasonal changes associated with the other Milankovitch cycles. That a 100 kyr periodicity characterizes both the eccentricity and the glacial-interglacial... 

A Closer Look at Glacial to Interglacial Climate Change... 

There is a much better record of the last major transition from glacial to interglacial climate than for earlier portions of the climate cycles. This transition therefore provides a useful starting point for examining the character of major climate changes, though each of these may have had unique elements. 

There is a striking contrast between the millennial variability of polar interglacial and glacial temperature histories. Whereas climate changes were frequent and large throughout... 

Fig. 18-13 High-resolution measurements of CO2 over the last glacial-interglacial transition from the Byrd ice core in west Antarctica (Neftel et ai, 1982). Also plotted is the oxygen isotope record temperature proxy from the Byrd core (Johnsen et ai, 1972). The time scale for the records plotted here is from Sowers and Bender (1995).

Glacial-interglacial variations in N2O have been described by Leuenberger and Siegentha-ler (1992) who showed that N2O levels during the glacial maximum at about 25 000 years B.P. were 190 ppbv (Fig. 18-17b). They found intermediate values of N2O (200-250 ppbv) between 30 000 and 40 000 years B.P. 

Broecker, W. S. and Henderson, G. M. (1998). The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes. Paleoceanography 13,352-364. 

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