>>Brajes+(OP)
If you pull up the last 2,000 years in the Yearly Average Observed Temperature anomaly, from 536 - 537 there should be a global average temperature anomaly of -2C to -5C from the Volcanic Winter of 536 (A period of 18 months where the sun was dimmed by volcanic ash), but the graph shows <1C. There's tree ring evidence of it from all over the world.
If they missed this, this puts into question all the rest of the data IMO.