Making a glacial cycle

The composition of Earth's atmosphere is largely governed by the by-products of the life that it sustains. Dry air from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other "noble" gases (by volume), but generally a variable amount of water vapor is also present, on average about 1% at sea level.

And alternatively, sudden glacial periods change the composition of life. The sudden implies that a large amount of biomass gets trapped beneath the ice. It doesn't go away, it becomes feed stock for co2 generating life which gradually recovers and co2 increases.  Hence the cycle completes, glaciers melt, volcanoes explode, the earth cools.

But the earth crust is still expanding in the north after the last glacial collapse. It is the relentless push of magma flow. I think it tends to spiral about 160 miles deep, spiral north and up. Canada and the arctic seem to portray a spiral look to it, like this has been the norm for geologic time. Add in the Cascade range which looks to be caused by a deeper spiral coming up between plates. The magma feed for Yellowstone seems northward, and up. I would think the most likely outcome has to be volcanic eruption, and the most likely solution geoengineering massive geothermal wells.