Andy May
The last time I wrote about climate change and civilization over the past 4,000 years was in 2016. First, we learned that various air and seawater temperature indicators, such as ice core δ18O or tree rings, are different. See here for a discussion of some of the temperature proxies used and their issues. Proxies have different accuracies, they are often sensitive to temperatures in different seasons, and have different temporal resolutions. Therefore, as Soon and Baliunas pointed out in 2003, they are local and “cannot be assembled into hemispheric or global quantitative complexes”.
The Global Average Surface Temperature (GAST) reconstruction relied upon in the IPCC AR6 report was completed by Kaufman et al. The authors acknowledge that the mean interval (time resolution) for each temperature is 164 years. Therefore, in order to compare the entire global instrumental temperature record with the proxy temperature record in a valid way, all daily readings since 1860 must be averaged to a single point. That is, the rate of warming since 1860 does not matter, the proxy record does not see 164 years of growth. Here Renee Hannon discusses the issue of comparing day-to-day modern instrumental temperature records with proxy temperature records.
Most temperature proxies are sensitive to only one season, but it is clear that seasonal temperatures change at different rates, and that changes in annual mean temperature are not the same as changes in seasonal temperatures. It is not possible to statistically blend them to create an accurate GAST record of the distant past. This issue is discussed in more detail here and here. Furthermore, most agents are affected by precipitation frequency and/or CO2 level and temperature. we know carbon monoxide2 Rainfall today is higher than it has been in the past few thousand years, and there is no way to correct for precipitation frequency or amount.
While merging hundreds of proxy data into a composite “global” or “hemispheric” record is a fool's errand, we can look at high-quality, high-resolution local proxy data from multiple locations to get a sense of the Qualitative understanding of global or hemispheric climate change, which is what Soon and Baliunas did in 2003. And Rosenthal et al. recorded a water depth of 500 meters through Indonesia in the Makassar Strait. The Makassar Strait record represents North Pacific sea surface temperatures, and the Unser Greenland record represents temperatures in the Greenland-Ronland-Agassi region. The Vinther record is superior to the more commonly used GISP2 records (Alley, 2004) and (Alley, 2000) because it takes into account elevation changes and ice flow. Both will break GISP2 reconstructions.
Both the Vinther and Rosenthal temperature records have a 20-year resolution over our 4000-year time horizon, which is a good resolution for a proxy. The accuracy of both recordings was good, around ±0.3°C. Both are Northern Hemisphere proxies but are 9,500 miles apart. They are compared with a comparable (10-year resolution) Antarctic proxy (Jouzel et al. 2007) in Figure 1 . Temperature trends vary with latitude.
As can be seen more clearly in Figure 1, the long-term decrease in temperature labeled the “New Ice Age” was primarily a Northern Hemisphere phenomenon. Figure 2 compares the Vinther and Rosenthal records in Figure 1 with selected historical events and Usoskin's Solar Minimum (SGM) record (Usoskin, 2017), shown as black points outlined in orange. Note that Figure 1 plots a smoothed version of the Vinther record, and Figure 2 plots the unsmoothed 20-year record. This figure prints well on 8.5×11 inch or A4 paper.
The Blytt-Sernander climate cycle (Schrøder et al. 2004) is determined at the top of Figure 2 . The dashed red line on the right is the smoothed HadCRUT4 combination of six filled grid cells (i.e., grid cells with temperature values) near Greenland for which sufficient data have been available since 1850. to Vinther records where they overlap. Both the Vinther and 20-year smoothed HadCRUT4 records show peaks around 1934. The red box is the average temperature at the same depth from 2004 to 2016 in the Global Marine Climate Database of the University of Hamburg (Gouretski, 2019).
Major historical climate periods are identified below solar minimum. Both indicators show a decrease in Northern Hemisphere temperatures, which bottomed out between 1700 and 1810. period) and the peak between 1700 and 1000 BC (the Minoan Warm Period). Agents differ significantly between 1400 to 800 BC, 200 BC to 0 AD, and 300 to 500 AD.
In 2000 BC, the most advanced cultures in the world were in the eastern Mediterranean, but there was chaos there. The Old Kingdom of Egypt had collapsed and was in the Egyptian Dark Ages, preceded by the collapse of the Akkadian Empire (mainly in today's Iraq). It was out of chaos that the development of the New Kingdom of Egypt in 1975 BC and the great Minoan “palaces” of Crete and surrounding islands was born. The Minoans had the most advanced ships of their time and traded extensively. Minoan trading culture reached its peak between 1690 BC and 1450 BC, when an unknown disaster destroyed all palaces in Crete except Knossos (Cunliffe, 2008, p. 190 ). Knossos survived until the collapse of the Mycenaean and Hittite civilizations in the Catastrophe of 1177 BC (Cline, 2014).
Further east, in northwest India and Pakistan, there was an advanced civilization called Harappa. Although the roots of the Harappan civilization can be traced to 5500 BC or earlier, the mature Harappan period existed from 2600 BC to 1300 BC, when the Harappan civilization collapsed. Although the Mesopotamian and Egyptian civilizations predate the Harappan civilization, it was probably larger than them (Encyclopedia Britannica).
In China, the Shang Dynasty ruled most of the Yellow River Basin from around 1600 BC until around 1046 BC (Encyclopedia Britannica), when it collapsed and was overthrown by King Wu of Zhou. In the last few decades of the Shang Dynasty, the climate was very turbulent, unusually cold and dry, and sandstorms occurred frequently. The Yellow River froze, resulting in frequent harvest failures and famines. Bad weather aided King Wu in his conquests (Behringer, 2010, p. 57).
In 800 BC, a “climate plunge” occurred in Europe and the Middle East, sometimes called the Hallstatt Catastrophe (Behringer, 2010, p. 60). It marks the beginning of the Iron Age in Europe and is associated with falling temperatures, longer winters and advancing glaciers. Mass migrations occurred in Egypt, and civil war broke out.
Around 200 BC, China was finally unified by Qin, but fell into chaos after Qin's death and established the Han Dynasty in 202 BC. It lasted until 220 AD. This was also the height of the Roman Empire (Behringer, 2010, p. 62).
In 280 AD, Roman Emperor Probus introduced grapes to Britain. The worsening climate triggered the so-called “Great Migration” period around 250 AD, which led to the difficulties of the Roman Empire and the collapse of the Han Dynasty in 220 AD. Later, around 375, the Huns invaded Europe, driving the Germans toward Rome and destroying it. Around 400 AD, Rome experienced a brief revival, but eventually collapsed. A climate catastrophe around 537 AD, possibly caused by a large tropical volcanic eruption, contributed to the empire's decline. The Dark Ages in Europe were about to begin.
One of the worst climate disasters in recorded history occurred around AD 800. In 843, a hungry wolf broke into a church in Senonais, France, during a service and attacked a flock of sheep. Charlemagne had wolf hunting parties in every county of his kingdom. In 784 AD, one-third of Europe's population died. In the decades around 800 AD, Europe was miserable. However, this period was less noticeable in China and Japan. However, the Maya suffered several severe droughts between 760 and 910 AD, and the Maya government and nobility disappeared due to severe population decline around 900 AD (Behringer, 2010, p. 71).
Around the mid-800s, as the North Atlantic warmed, the Vikings emerged and conquered parts of Britain, Ireland, Russia, France, and Sicily. The Medieval Warm Period began earlier in northern Europe than in the south, which worked to the Vikings' advantage. They settled in Greenland in 985 AD and prospered until around 1410, when the last letter from Greenland reached the Vatican. Sometime after 1410 they all perished, and some of their farms now lie in permafrost. During this period, ships trying to sail to Greenland were unable to pass the abundant icebergs.
Although most sources believe the Little Ice Age began around 1300, it didn't actually begin until the late 1400s. The most severe period of the Little Ice Age was from about 1645 to 1715, although periods of extreme cold occurred from 1310 to 1322, 1560 to 1600, and 1800 to 1850. The period from 1560 to 1660 is known as the “Age of Witch Persecutions” (Behringer, 2010, p. 130). Someone or a group has to be blamed for the bad weather, and the group most often blamed are older, single women. Others claimed the weather was God's punishment for sins such as sodomy or staging a play.
The impact of the severe weather of the Little Ice Age on society was horrific. There were more wars fought around the world in the mid-1600s than in any other era before the 1940s (Parker, 2008). In the 1640s, the Ming Dynasty and the Polish-Lithuanian Commonwealth collapsed. Serious rebellions rocked Britain, Spain, Russia, France and Istanbul. In London, King Charles I was the first king to stand trial. One of China's later emperors, Yongzheng, estimated that more than half of China's population died during this period (Parker, 2008).
In France, the Fronde Rebellion (1648-1653) and the resulting disease, deprivation and misery may have killed two-thirds of the population of the villages surrounding Paris. Thomas Hobbs wrote in 1651 that “man's life is solitary, poor, dirty, brutish, and short” (Parker, 2008).
It was not just cold that caused the misery of the Little Ice Age, but also droughts, severe storms, and occasional sweltering summers (May & Crok, 2024). The weather during the Little Ice Age was much more extreme than today. I have written elsewhere that storms were much more severe during the Little Ice Age, see Figure 6 here. This is logical because the temperature gradient from the tropics to the poles is steeper during cold periods, and it is this gradient that powers storms.
As Geoffrey Parker writes, extraordinary claims about people's suffering in the 1600s have been proven to be true. Understandably, many people today look back on that period with skepticism about these stories, but they have been proven to be true time and time again. The Little Ice Age was real and devastating to humanity.
Many paleoclimatologists, archaeologists, and historians agree that there is a correlation between solar activity and climate. They also agree that humans perform better in warmer periods than in colder ones. It is time for the “consensus” to face up to historical and archaeological facts.
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