Evidence that Medieval Warm Period was global

MWP was global?

“We must get rid of the MWP” a certain warmist once said, and who can blame him? Here was a period in recent history where temperatures were warmer than today without any assistance from man-made emissions.

Michael Mann’s Hockey Stick obliterated both it and the Little Ice Age through the use of some tricky algorithms which McIntyre and McKittrick debunked comprehensively. The IPCC, whilst not erasing it completely from the historical record, claims that it was a “local event” in the Northern Hemisphere only and therefore not a genuinely global phenomenon, thus preserving the modern warm period as unusual.

But now evidence lends weight to the argument that the MWP was a global event, with effects reaching Antarctica:

More peer-reviewed science contradicting the warming-alarmist “scientific consensus” was announced yesterday, as a new study shows that the well-documented warm period which took place in medieval times was not limited to Europe, or the northern hemisphere: it reached all the way to Antarctica.

The research involved the development of a new means of assessing past temperatures, to add to existing methods such as tree ring analysis and ice cores. In this study, scientists analysed samples of a crystal called ikaite, which forms in cold waters.

“Ikaite is an icy version of limestone,” explains earth-sciences prof Zunli Lu. “The crystals are only stable under cold conditions and actually melt at room temperature.”

Down in the Antarctic peninsula that isn’t a problem, and Lu and his colleagues were able to take samples which had been present for hundreds of years and date their formation. The structure of Ikaite, it turns out, varies measurably depending on the temperature when it forms, allowing boffins to construct an accurate past temperature record.

A proper temperature record for Antarctica is particularly interesting, as it illuminates one of the main debates in global-warming/climate-change: namely, were the so-called Medieval Warm Period and Little Ice Age merely regional, or were they global events? The medieval warmup experienced by northern Europeans from say 900AD to 1250AD seems to have been at least as hot as anything seen in the industrial era. If it was worldwide in extent that would strongly suggest that global warming may just be something that happens from time to time, not something caused by miniscule concentrations of CO₂ (the atmosphere is 0.04 per cent CO₂ right now; this figure might climb to 0.07 per cent in the medium term).

The oft-mentioned “scientific consensus”, based in large part on the work of famous climate-alarmist scientists Michael Mann and Phil Jones and reflected in the statements of the Intergovernmental Panel on Climate Change (IPCC), says that isn’t true. The IPCC consensus is that the medieval warming – and the “Little Ice Age” which followed it – only happened in Europe and maybe some other northern areas. They were local events only, and globally the world was cooler than it is now. The temperature increase seen in the latter half of the 20th century is a new thing caused by humanity’s carbon emissions.

Lu and his colleagues’ new work, however, indicates that in fact the medieval warm period and little ice age were both felt right down to Antarctica. (source)

This also inconveniently shows that the science isn’t quite settled just yet.