Medieval Warm Period Undeniable, Pronounced In Antarctica And Poland, 2 New Studies Show

Natural cycles drive our climate

The latest video by the Germany-based European Institute for Climate and Energy (EIKE) looks at CO2 and the troublesome Medieval Warm Period, which has long been a thorn for climate alarmists.

Antarctica was warmer during the Medieval Warm Period, enhancing penguin population. Image generated by Grok

Hat-tip: Klimanachrichten

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.

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.

After comparison with historical records of penguin populations from Cape Bird, Dunlop Island and Cape Adare, it was found that all penguin populations increased in the Ross Sea during the period 750 to 1350 AD. The population trend also coincided with extreme swings in the El Niño and SAM circulations.+

From this, the researchers concluded that SAM-ENSO could promote the inflow of circumpolar and modified circumpolar deep water into the Ross Sea and thus increase the influx of nutrient-rich deep water, together with a warmer climate, could promote the efficiency of open ocean areas, so-called polynyas, and the population increase of Adélie penguins.

The study shows the important role of ENSO and SAM as triggers of strong climate fluctuations.

These natural processes are still taking place today and have by no means ended with the start of the CO2 increase.

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.

The coldest conditions in the entire study period were recorded in the first half of the 11th century (both in winter and summer) and in the second half of the 15th century (only in winter). The greatest continentality of climate occurred in the 15th century. A good agreement was found between the reconstructions of the Polish climate and many reconstructions available for Europe.

The two new studies from Antarctica and Poland indicate that the natural climate factors still need to be much better understood in order to be able to incorporate them faithfully into climate models. Currently, the simulations do not attribute a major role to natural climate events, which is a serious mistake.

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