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Longer Term Auto Correlation

Notes:

When the 22K and 41K effects are averaged out, a longer period influence emerges. The evenly spaced correlation peaks every 96K years clearly indicates a 96K year periodic effect. This corresponds to the periodic change in the Earth's orbit as it shifts between circular and elliptical. There is some modulation on this, which appears to be an even longer 400K-500K year influence.

Another long term effect results from how the phase relationship between the 22K and 41K forcing effects varies. This goes through a complete cycle every 900K years. During the warmest interglacial periods their peaks tend to be aligned and during the deeper glacial epochs, their lows tend to be aligned. This alignment also seems related to the shift from 40K to 100K glaciation periods. Their present alignment is acting to stabilize the current interglacial and keeping it a little cooler than prior ones.