HR: 1340h
AN: U43A-0742    [Abstracts]
TI: Long-Term Sun Climate Connections, Revealed by the Analyses of Historical and Other Proxy Records
AU: * Pang, K D
EM: kevindpang@aol.com
AF: Retired, 4715 Groveland Lane, La Canada, CA 91011 United States
AU: Yau, K
EM: kyau@jpl.nasa.gov
AF: JPL, M/S 230-101 4800 Oak Grove Dr, Pasadena, CA 91125 United States
AB: The Sun, once considered constant, actually goes through 11-year, decadal, centennial, and even longer cycles. Our analysis of historical sunspot and aurora records, carbon-14 and beryllium-10 abundances from long-lived trees and deep polar ice cores, respectively, shows that it has gone through nine long cycles in the past 1800 years. Although these changes amounted to $<$1% of the total irradiance there is clear evidence they produced corresponding changes in the climate [Pang and Yau, Eos, 83, No. 43, 481, 2002]. For example during the Maunder Minimum (1645-1715) sunspots were rarely seen (about once in ten years from Europe or China). Total solar irradiances, reconstructed from historical sunspot records, were 0.25% lower then. This correlates nicely with an estimated 0.5-degree drop in Northern Hemisphere summer surface temperatures during the Little Ice Age [Lean, GRL 22, 3195, 1995]. We have also analyzed Chinese historical weather records for comparison. Reports of unseasonable cold are classified by the degree of severity: (1) Late (April-June) or early (July-September) killing frosts; (2) Bitter cold/heavy snowfall; and (3) Heavy sustained snowfall, bitter cold with frozen wells, rivers and icebound seas. The latter cases were often widespread and multi-year. All categories occurred most frequently during the coldest part of the Little Ice Age. The Category 3 episodes were in 1652-54, 1656, 1664, 1670-72, 1676-77, 1683, 1688-91, 1716, and 1718-19. For example the Yangtze River and its lakes froze up to 3-4 times in 1650-1700. The coldest period thus coincides with the Maunder Minimum, and is consistent with general circulation model hindcast winter conditions for China [Shindell, Science, 294, 2149, 2001]. There was only one Category 3 episode between the Maunder and Dalton Minima--in 1761 (due to a large volcanic eruption); and two in the Dalton Minimum (1795-1825)--in 1796 and 1814-17. The Sun has gradually brightened since the Dalton Minimum. But the climate of China remained cold through the 19th century, as in the rest of the world, probably due to increased volcanic aerosol loading of the atmosphere [Sato, JGR 98, 22987, 1993]. The climate of China seems to have been warm during the Late 14th-Century Maximum (1350-1410). We have found only one Category 1 episode--in 1393. It then turned cold during the Sporer Minimum (1410-1590). Category 3 episodes occurred in 1453-54, 1493, 1513, 1569, and 1577-78. Lesser ones were also common. Some scientists suggest that the Little Ice Age actually began in the 13th Century, and is comprised of the Wolf (1280-1350), Sporer, Maunder, and Dalton Minima. It and the Little Climate Optimum make up a millennium-long cycle [Broecker, Natural History 101, 6, 4/1992]. The warm Classical Age and cool Dark Ages, the cold Iron Age (1st millennium BC), and warm Bronze Age (2nd and 3rd millennia BC) could be considered still earlier millennial cycles. These trends are generally consistent with carbon-14 deviations from its long-term variations. There is also some historical and archaeological evidence for the early trends, as rhinoceros and elephant herds were abundant along the Yellow River during the Shang dynasty (1600-1100 BC). The tropical fauna and flora have since disappeared, as North China gradually turned cold and arid. We conclude that the climate of China generally follows world trend. The major forcing seems to have been changing solar luminosity on a decadal to millennial timescale. Volcanic eruptions and changing ocean currents also frequently perturbed the climate.
DE: 3344 Paleoclimatology
DE: 1620 Climate dynamics (3309)
DE: 1650 Solar variability
SC: Union [U]
MN: 2004 AGU Fall Meeting