Egtved Girl

 

Understanding Global Warming

The Egtved Girl and her time

 

Karin Margarita Frei of The National Museum of Denmark, Copenhagen has convincingly told us about the Egtved girl and her age as a warm and fruitful period - also warmer than today, hence the interest in the Minoan Warm Period - hyperlink. That the climate was really warmer at that time can be deduced from the fact that in the Bronze Age, millet was grown in southern Scandinavia. Millet is grown today in tropical and subtropical areas. No remains of stables from that time have been found. Apparently the cattle were kept out all year. So probably the climate in the middle of the Bronze Age was about 2 degrees warmer than in the present.

40,000 Bronze Age mounds have been registered. There have been many more, but especially on the islands they have been plowed down. The large number, testifies to an unbelievably rich time, but also to a significant class difference. They are set as a memorial to large farmers who have also been merchants. Such was the case with the large farmer in Egtved, who was entrusted with a foster daughter by his friend and business associate in the Black Forest far to the south in Germany.

Figure 1.The Egtved Girl in her light airy skirt makes it easy for us to believe her time was warm and nice.

Karin Margarita Frei has so to speak brought the Egtved Girl to live again. As 15-year-old, I imagine she became the foster daughter of a large farmer and merchant at Egtved, Denmark. She came from a business relationship in the Black Forest, Germany - maybe because her foster father was childless himself. She is on home visit a few times. On the last trip back, she brought with her a boy - her little brother I assume. They both fall ill on the journey and die 1370 BC. The Egtved family gives her and the boy a beautiful burial with a burial mound 22 m wide and 4 m high. Her foster parents must have been fond of her, but it has also been important to show her German family and trading partner their utmost honor and respect. Her travels have followed the waterways. They must have been organized as "package tours" by merchants who have provided stays and barges along the way. It's been expensive. Also, her funeral was extremely expensive, but her foster family could afford it. They lived in a period of warm weather - better than today. It is the warm periods that bring wealth and prosperity.

Lushness and carbon dioxide go hand in hand. From a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide, according to a study published in the journal Nature Climate Change on April 25. 2016 – hyperlink. During the warm periods, the carbon dioxide equilibrium is shifted over the oceans, giving off more to the air. Was this too the case in the time of the Egtved girl?

Prof. Hans Oeschger, Bern was among the first to analyze CO₂ in the Greenlandic Camp Century ice core. He found in average 435 ppm total CO₂ down to a depth of 1000 m – it is the all Holocene period - hyperlink. CO₂ in air bubbles from the EPICA Dome C, Antarctica from the same Holocene period doesn't show as much as a wrinkle - hyperlink. Prof. Zbigniew Jaworowski, Warsaw has objected that the reactive and soluble CO₂ is depleted during the compression and later sampling of the ice – 1991 and 2007. Although these objections are now swept off the table in the academic community, the generally low CO₂ variation in ice cores still wonders.

Stomatal Index

… an alternative method.

 Levels of carbon dioxide in Earth's atmosphere change over time — so at times when the atmosphere is carbon-dioxide-rich, plants can get away with having fewer stomata since each individual stoma will be able to bring in more carbon dioxide. During those high-carbon-dioxide times, plants with fewer stomata will have an advantage and will be common. On the other hand, when carbon dioxide levels are low, plants need many stomata in order to scrape together enough carbon dioxide to survive. During low-carbon-dioxide times, plants with more stomata will have an advantage and will be common. Credit to the University of California Museum of Paleontology's Understanding Evolution - hyperlink.

Figure 2. The GISP2 proxy-temperatures are based on δ18O isotope in the ice core originating from evaporation from the surrounding sea. The Camp Century samples are analyzed by Hans Oeschger and the EPICA Dome C by Eric Monnin, both affiliated with University of Bern. The stomata are analyzed by Catherine Jessen, National Museum Copenhagen.

Tutankhamun died 1325 BC at same age as our Egtved girl, only 45 years before her. Olive leaves grown today have 33% fewer stomata than the olive leaves in the floral collar found in his tomb. This indicates a lower carbon dioxide concentration at that time - hyperlink.

During warm periods, the equilibrium over the oceans shifts towards higher concentrations of CO₂ in the air (Henry's Law). This is not reflected in the EPICA Dome C ice core (by Eric Monnin) – hyperlink.

New research by Dorte Haubjerg Søgaard, the Greenland Institute of Natural Resources, Nuuk has shown that also sea ice removes CO₂ from the atmosphere – hyperlink and private communication. This means that both sea ice and sea act as a CO₂ sink, which reduces the CO₂ concentration in the Arctic Sea providing moisture for snowfall on the inland ice. It contributes to lower CO₂ in Artic ice cores than in the air at our latitudes and contributed to low IPCC past CO₂ estimates.

Analysis of the contained air in the ice cores is insufficient. Only a total carbon determination is sufficient because carbon dioxide is a reactive gas as opposed to nitrogen. Hans Oeschger was aware of this, but is everyone?

Hans Oeschger measured total carbon and found variations, but the samples were not dated - only the depth. The 427 ppm CO₂ is his average for 700-900 m depth - hyperlink. Catherine Jessen reconstructed CO₂ from oak and birch leaves, but neither does the stomata change with the warm period (red dots in the figure are moving 3 pts average) - hyperlink. Catherine describes the period 1500-800 BC as stable with precipitation peaking 1400 BC.

Henry's law cannot be ignored, but we miss data to quantify its effect. With three quite different CO₂ estimates, past carbon dioxide cannot be determined with any certainty nor credited for the lushness that must have been during the time of the Egtved Girl.

Carbon dioxide during the Minoan War Period

Zbigniew Jaworowski is right – past CO₂ concentrations are estimated too low. Hans Oeschger is right too, but have his samples been contaminated - and how? Stomata counts are a bit noisy, but nevertheless appear credible.

Egtvedpigen levede i bronzealderen og blev begravet for cirka 3.400 år siden. Her er en rekonstruktion, lavet af Sagnlandet Lejre, af det tøj, man fandt i hendes kiste.

 Understanding Global Warming, Oversigt - LINK