A graphic illustration of this is given in the Figure. The dots in black are 1980-2007; those dots reduced and in red are for 2010-2049 in an extrapolation. The center of gravity calculations are performed in 3-dimensional space and then projected onto the normal cylinder tangent to the planet at the equator.
My paper with the same name as this post describes more fully the ideas here.
(Thanks to Google Earth for help with this. To transform a 3-dimensional sphere into an unfolded 2-dimensional flat plane, the mapping is not a Hilbert space projection. For one, the tangent normal cylinder is only locally linear; it is therefore not a linear space. I calculated the dynamics using R; I generated the sequence of world maps in python; and I then used gimp and ImageMagick batch-processing to produce the final animation.)