MWP designates the Medieval Warm Period.
Examples
The Medieval Warm Period had completely vanished. Even the previously acknowledged ‘regional effect’ now left no trace in the record.
(Our Beloved Bishop)
The idea is to show something like this:
Source: https://www.drroyspencer.com/2013/07/senate-epw-hearing-climate-change-its-happened-before/
Greenland. Vikings occupied Greenland until it started to get cold around—
☞ They left Greenland at least a century after it got cold, probably because the ivory market fell after Europeans rediscovered Africa.
Resources
Description of the Medieval Warm Period and Little Ice Age in IPCC reports
Climateball Episodes
2012-10; The Afterlife of IPCC 1990 Figure 7.1; note Tom Curtis‘ comment.
2012-09; Pushing Back on Climate Hype; according to PDA, this thread is classic.
ClimateBall 