Russ Steele
The Sacramento Bee has an interesting story about large trees found 80 to 120 feet below the surface in Fallen Leaf Lake, indicating the lake level was once much lower and for a long period of about 200 years. Full story here.
These trees grew during the Medieval Warm Period, which lasted from about AD 950–1250. Similar submerged medieval trees have been found in Tenaya Lake, Yosemite National Park and other glacial lakes in the Sierra, including Walker Lake, Mono Lake, the West Walked River, Owens Lake (desiccated in the MWP), Osgood Swamp near Lake Tahoe, Independence Lake north of Tahoe, according to a study published by Ccott Stine, 2001,The Great Droughts of Y1K, in Sierra Nature Notes.
National Academy of Sciences panelist Franco Biondi, together with Kleppe and Scotty Strachan , in a 2005 poster presentation entitled Underwater Dendrochronology of Sierra Nevada Lakes included the following pictures of divers in 1990 taking core samples.
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These trees grew during the Medieval Warm Period, which lasted from about AD 950–1250. Similar submerged medieval trees have been found in Tenaya Lake, Yosemite National Park and other glacial lakes in the Sierra, including Walker Lake, Mono Lake, the West Walked River, Owens Lake (desiccated in the MWP), Osgood Swamp near Lake Tahoe, Independence Lake north of Tahoe, according to a study published by Ccott Stine, 2001,The Great Droughts of Y1K, in Sierra Nature Notes.
National Academy of Sciences panelist Franco Biondi, together with Kleppe and Scotty Strachan , in a 2005 poster presentation entitled Underwater Dendrochronology of Sierra Nevada Lakes included the following pictures of divers in 1990 taking core samples.
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Philip Catarino, one of the divers cited by Stine, has a 2000 online article, Reconstructing Ancient Avalanches of the Sierra Nevada Range (no longer on line) in which he observed:
During the last 500 years, a wet climate, punctuated by intermittent but substantial droughts, began to dominate the region, and lake levels again rose and cirques glaciers reformed in the Sierra. A series of substantial droughts are documented during this period, however. Dozens of submerged tree stumps are located up to 300 feet below the present day level of Donner Lake a tributary of the Truckee River; carbon –14 samples from one stump date from AD 1433 (Lindstrom and Bloomer 1994). Another warm period, documented by tree-ring studies and Truckee River run-off, dated between AD 1579-1585, and again around AD 1630 (Hardman and Reil 1936). It is possible that Lake Tahoe contributed relatively little water to the Truckee River during the last 200 years. During the century between the mid 1700s to mid 1800s, the level of Lake Tahoe may have been below its rim, with no water flow into the Truckee River. This is documented by a submerged stump in the Upper Truckee River Delta dating from AD 1720 (Lindstrom 1996a), one from Donner Lake dating from AD 1800 (Lindstrom and Bloomer 1994) and one in Emerald Bay dating to AD 1840 (Lindstrom 1992). The 40 years between AD 1875-1915 were the longest period during which the flow of the Truckee River was above the average. During the AD 1930s drought, Lake Tahoe ceased to flow from its outlet for six consecutive years. Drought within the last decade (late 1980s to 1990s) either stopped Tahoe’s flow into the Truckee or reduced it to almost nothing.
What is the significance of this to modern times? It is clear evidence that the Sierra have been much warmer than today for long periods, up to 200 years. This warming had nothing to do with human CO2 emissions. The flora and fauna survived then and will again if the climate warms. However, today I am more interest in long term cooling in the Sierra, which will have a more immediate impact on our lives in California. Implementation of AB32 Scoping Plan to reduce CO2 will only exacerbate the problem. Vote YES on Prop 23.
H/T to Climate Audit that covered the underwater trees story in December 2006.
