Dr. Sebastian Lüning (geologist) and Prof. Fritz Vahrenholt (chemist) at their website here discuss a recent (peer-reviewed) paper appearing in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.
I’ve translated and edited the text in English with their kind permission.
Oases of the Chinese Taklamakan Desert Greened Up In Sync With Solar Millenial Cycles
by Sebastian Lüning and Fritz Vahrenholt
The Taklamakan Desert is the 2nd world’s largest sand desert after the Rub el-Khali Desert in Saudi Arabia. A Chinese-Australian team of scientists lead by Keliang Zhao of the Chinese Academy of Sciences in Peking studied the sediment-profiles from an oasis at the edge of the Taklamakan where they reconstructed the climate of the last 4000 years based on pollen. The scientists published their results in March, 2012.
The Taklamakan Desert is bounded by the Kunlun Mountains to the south, and the desert Pamir Mountains and Tian Shan to the west and north. The oases of the Taklamakan react very sensitively to climate fluctuations and draw their water from the surrounding mountains regions via groundwater and surface water feed-in. Fluctuations in the amount of meltwater being fed in are made apparent through the ever thirsty oasis vegetation. The scientists studied the pollen.
Zhao and his colleagues extracted an 8.5 meter long sediment core from an oasis. The sediment came from melt water sands as well as wind deposits. The scientists analyzed the pollen composition from a total of 105 samplings which they extracted along the sediment profile every 5-10 cm. Using pollen data, they reconstructed the moisture and vegetation density in the oasis over the last 4000 years.
The researchers found three time periods where the oases grew and expanded in wetter climate conditions: These time periods were 4000-2620 before today, 1750–1260 years before today and 550-390 years before today (see Figure 2). Interestingly these intervals coincide precisely with the cold phases of the North Atlantic as distinctly described by Bond et al. (2001), the so-called Bond Cycles. Gerard Bond was able to show that the North Atlantic cold phases occurred during times of low solar activity, i.e. caused by fluctuations in activity. In the Chinese region of investigation, these solar periods of weak activity led to wet periods. The last wet period coincided with the Little Ice Age. However, during the Medieval Warm Period, warm and dry conditions prevailed.
The team of scientists therefore suspect that during the wet spells, the moisture-carrying west winds shifted southwards towards the area of investigation. This led to more precipitation in the form of snowfall in the surrounding mountains. The glaciers in the mountains expanded due to the larger snowfalls and globally cooler conditions. This also increased the feed-in of springtime meltwater into the Taklamakan oases accordingly, thus leading to greener conditions. The westwinds in the region get their moisture mostly from the Atlantic, Mediteranean, Black and Caspian seas.
The study is yet another beautiful example of the global climatic impact of the solar millenial cycles (also see our recent article “New Study in PNAS Confirms Solar Impact Over the Last 9000 Years“ and “Solar Millennium Cycles Regulated the Wet and Dry Periods of the Mediteranean During the Roman Times“, also see pages 68-75 of our book “Die kalte Sonne“.
Figure 2: Reconstruction of the moisture development in the region of study using pollen for the last 4000 years. The shaded gray areas depict wet periods in the Tarim Basin. These coincide with the cold phases in the North Atlantic (numbered 1, 2, 3) and solar weak phases, as described by Bond et al. (2001). Chart from Zhao et al. (2012).