You are absolutely on the right track Karl. Among other additional influences all coming together at the same time, solar insolation is more than likely the biggest influence. Here is another graph for your files, very important is looking at this on a much much longer timeline which so far they refuse to do.
Note that solar insolation peaked and started to decline about 8,000 years ago moving us into the new coming glacial period. It's pretty self explanatory as a visual.
https://www.ncdc.noaa.gov/abrupt-climate-change/Glacial-Interglacial%20Cycles
