The Medieval Warm Period was (as the name suggests) a prolonged period of unusually warm weather, particularly in northern Europe. You could grow wine grapes in Britain in these years, which is difficult to do now. It's a troublesome time for climate scolds to explain because they can't reproduce it with their models, the same models that they point to now to claim that the Earth will burst into flame in the next few years unless we all move into 15-minute cities (rabbit warrens) and start eating bugs. The Medieval Warm Period (MWP) lasted from 700 to 1,300 AD, a time when there were conspicuously few coal-fired power plants and people driving SUVs.
That problem has now gotten worse, with two new studies largely around the Medieval Warm Period that are debunking the modern climate-change models.
The Medieval Warm Period, the natural warm phase between 700 and 1300 AD, cannot be reproduced climate models because the simulations react primarily to CO2. Back then CO2 was not a factor because its concentration level in the atmosphere was pretty much constant. That’s why people would rather keep the Medieval Warm Period quiet.
But the facts speak for themselves. Two studies now add further pieces to our knowledge of the medieval climate.
Facts are stubborn things, and the primary fact here is that the MWP was a natural event; there simply weren't enough people burning dung to heat their hovels to affect the CO2 content of the atmosphere.
The first of the two studies mentioned here was undertaken in Antarctica.
In October 2023, a paper by a team of researchers led by Zhangqin Zheng from the University of Science and Technology of China in Hefei was published in the journal Quaternary Science Reviews. It deals with historical changes in the Adélie penguin population in the Ross Sea region of Antarctica and their climatic influences.
Two atmospheric-oceanic circulation patterns, the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO), have a major influence on the climate and marine ecosystems in the Ross Sea region. From a historical perspective, however, the influence of atmospheric-oceanic circulation patterns on penguin populations in this region remains unclear. The researchers analyzed sediment cores from abandoned penguin colonies on Inexpressible Island in the Ross Sea and reconstructed the changes in the populations of Adélie penguins over the past 1500 years. Zhangqin Zheng and colleagues found that the penguin population on Inexpressible Island peaked between 750 and 1350 AD, possibly due to habitat expansion in a warmer climate during the Medieval Warm Period.
The second study took place in Poland.
The other study comes from Poland. The research group led by Rajmund Przybylak from Nicolaus Copernicus University in Toruń, Poland, published their work in the journal “Climate of the Past” in November 2023. The article presents current findings on climate change in Poland for the period from 1000 to 1500 AD. This period also includes the Medieval Warm Period. The scientists first studied all available quantitative climate reconstructions that have been produced for Poland in the last two decades. They also produced four new reconstructions using three dendrochronological series and an extensive database of historical source data on weather conditions. The growth of conifers in the lowlands and mountains of Poland depends on the temperatures in the cold season, especially in February and March. All available reconstructions based on dendrochronological data refer to this time of the year. Summer temperatures were reconstructed using biological proxies and documentary evidence. However, the latter are limited to the 15th century. The winter temperature was used as a proxy for the annual temperature proxies, instead of the usual use of the summer temperature.
The Medieval Warm Period probably occurred in Poland from the late 12th century to the first half of the 14th or 15th century. All analyzed quantitative reconstructions indicate that the Medieval Warm Period in Poland was comparable or even warmer than the average temperature in the period 1951-2000.
So, Poland, in the MWP, was "comparable or warmer" than the average temperature of the same region from 1951-2000. That is before and after the Industrial Revolution.
The causes of the MWP are not well understood, but some possible causes include an increase in solar activity and a historical low in global volcanic activity; volcanoes tend to spew nasty dusts and aerosols that can block sunlight and result in a cooling effect. Not humans.
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Here's where the problems with the climate-scold models lie: The study from Antarctica, as well as the one from Poland, give us broad climate data — using quantifiable methods, like dendrochronology (tree rings). And the causes of the MWP are still not well-known — but there is no application of the current, prevalent climate models that can account for them. That may be because the current models are working backward from a conclusion, that being that human-caused CO2 output is the primary driver of climate change; it may simply be because a planet's climate is a vast, chaotic system that we simply don't understand very well.
And there's another pesky fact: The current models don't adequately take natural causes into account. And the MWP demonstrates that we still don't understand what all those natural causes might be. So, there's no reason to give up our comfortable, energy-reliant lifestyles yet, no matter what John Kerry might think.
