So I wonder if this 0.048 Wm ^ -2 figure (AD1750 - 2000) is the net annual change in insolation due to orbit (of which duncansteel CSI is but a small part). (skepticalscience.com)
Small changes in insolation driven by changes in the Earth's orbit can push the planet into or out of an ice age through the planet's «climate feedback» mechanisms. (planet3.org)
These are thought to be driven by the large regional changes in insolation driven by orbital changes. (realclimate.org)