There are lots of those. I will stick with NASA.
If we DID get a GSM: temperatures would drop by 0.3–0.6°C. No Ice Age.
Booby nagged me to watch this video about the history of the LIA. In that video the fact of the much higher CO2 in the atmosphere was mentioned. Booby must have forgotten that.
Remember some of the things that video suggested may have caused the LIA, Booby?
1. MWP melted so much Arctic/Greenland/Antarctic ice the big ocean currents were disrupted
2. Lots more volcanic activity to cool the earth.
3. Forgot what cause 3 was

The Maunder Minimum dropped temperatures a bit more.
ATM: the Gulf stream is fine and there has not been the huge vulcanism to cool the earth so if we got a MM not much difference would be felt.
Dubyne knows that vulcanism was thought to be one of the causes of the last LIA and he is trying to talk up volcanic activity but the volcanoes are not obliging, obviously: