[Wonder Warthog]

"First of all, I think you're mixing up two terms. There was a "Holocene Climate Optimum" -- the period you're referring to is most commonly called the "Medieval Warm Period" or MWP."

Yeah, you're right. Brain-fart on my part.

"Can you show provide references that indicate the MWP was truly global? The main problem is that there is so little data from the Southern Hemisphere."

No--I'm past the point of keeping references on this stuff--got other stuff to keep me busy. I just keep seeing different studies from widely separated geographic areas all pointing to the "globalality" of the "Medievel Warm Period". One I "do" recall was from Australia. Used proxy oxygen isotope measurements on some shellfish in sediment.

[PeaceBeWithYou]

Here's a link that mentions New Zealand, Australia, California, Argentina, Chile, Southern Peru as well as Southern Africa were all warmer during the MWP. All peer reviewed too.

Revising 1,000 Years of Climate History.