Climate change caused African lakes to dry up 90 meters in less than 100 years!

A paper published today in Palaeogeography, Palaeoclimatology, Palaeoecology finds Kenya experienced exceptional climate change 5,000 years ago at the end of the Holocene Climate Optimum, when lake levels decreased 90 meters [296 feet] in less than 100 years. According to the authors, "Rapidly decreasing water levels of up to 90 meters over less than a hundred years are best explained by changes in solar irradiation either reducing the East African-Indian atmospheric pressure gradient and preventing the Congo Air Boundary from reaching the study area, or reducing the overall humidity in the atmosphere, or a combination of both these effects."



The paper adds to hundreds of other peer-reviewed studies describing solar amplification mechanisms by which tiny changes in solar activity are amplified to large-scale effects on climate. 



However, according to the IPCC climate geniuses, this is impossible because total solar irradiation is "constant" over the short-term, and such solar amplification mechanisms are "controversial."

Note top 2 graphs are proxies for temperature and precipitation [d18O]

Fig. 10. 

Comparison of water levels in East African lakes for the past 16,000 years: (Turkana - Garcin et al., 2012 (filled curve),Johnson et al., 1991 (dotted curve), Brown and Fuller, 2008 (dashed curve); Lake Abhè (Gasse, 2000); Ziway-Shala -Gillespie et al., 1983; Nakuru - Richardson and Dussinger, 1986; Bosumtwi - Shanahan et al., 2006) with the potassium record as an aridity index for the Chew Bahir basin (Foerster et al., 2012), the oxygen-isotope records from Qunf (Fleitmann et al., 2003) and Dongge caves (Dykoski et al., 2005), and insolation variations for NH summer, fall, and spring (Laskar et al., 2004). Dotted white lines indicate water level estimations from discontinuous records. AHP–African Humid Period, YD–Younger Dryas, MWP–Medieval Warm Period. All original radiocarbon dates have been converted into calendar years.

The effects of solar irradiation changes on the migration of the Congo Air Boundary and water levels of paleo-Lake Suguta, Northern Kenya Rift, during the African Humid Period (15–5 ka BP)

• Annett Junginger^a, b, , , 


• Sybille Roller^c, 


• Lydia A. Olaka^b, d, 


• Martin H. Trauth^a

• ^a Institute for Earth and Environmental Sciences, University of Potsdam, Karl-Liebknecht-Str. 24, Am Mühlenberg 3, D-14476 Potsdam, Germany


• ^b DFG Graduate School Shaping the Earth’s Surface in a Variable Environment, University of Potsdam, Karl-Liebknecht-Str. 24, 14476 Potsdam, Germany


• ^c Senckenberg Forschungsinstitut und Naturkundemuseum Frankfurt, Senckenberganlage 25, 60325 Frankfurt, Germany


• ^d Geology Department, University of Nairobi, P.O. BOX 30197, Nairobi

Highlights

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New approach for reconstructing water-level variations using 3 independent methods.

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A new 15 ka high-resolution water-level record for paleo-Lake Suguta, East Africa.

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An eastward shift in the Congo Air Boundary caused long-term climatic changes.

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Short-term lake water level fluctuations are due to variations in solar irradiation.

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Complex interactions interpreted between West African and Indian summer monsoons.

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Abstract

The water-level record from the 300 m deep paleo-lake Suguta (Northern Kenya Rift) during the African Humid Period (AHP, 15–5 ka BP) helps to explain decadal to centennial intensity variations in the West African Monsoon (WAM) and the Indian Summer Monsoon (ISM). This water-level record was derived from three different sources: (1) grainsize variations in radiocarbon dated and reservoir corrected lacustrine sediments, (2) the altitudes and ages of paleo-shorelines within the basin, and (3) the results of hydro-balance modeling, providing important insights into the character of water level variations (abrupt or gradual) in the amplifier paleo-Lake Suguta. The results of this comprehensive analyses suggest that the AHP highstand in the Suguta Valley was the direct consequence of a northeastwards shift in the Congo Air Boundary (CAB), which was in turn caused by an enhanced atmospheric pressure gradient between East Africa and India during a northern hemisphere insolation maximum. Rapidly decreasing water levels of up to 90 meters over less than a hundred years are best explained by changes in solar irradiation either reducing the East African-Indian atmospheric pressure gradient and preventing the CAB from reaching the study area, or reducing the overall humidity in the atmosphere, or a combination of both these effects. In contrast, although not well documented in our record we hypothesize a gradual end of the AHP despite an abrupt change in the source of precipitation when a decreasing pressure gradient between Asia and Africa prevented the CAB from reaching the Suguta Valley. The abruptness was probably buffered by a contemporaneous change in precession producing an insolation maximum at the equator during October. Whether or not this is the case, the water-level record from the Suguta Valley demonstrates the importance of both orbitally-controlled insolation variations and short-term changes in solar irradiation as factors affecting the significant water level variations in East African rift lakes.