Reconstructed drought history, north-central Great Basin, 1600-1982 [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring chronologies, developed from cores from Pinyon pines growing on climatically sensitive sites in the north-central Great Basin, have been used to reconstruct precipitation and drought histories of the area from A.D. 1600 to 1982. Analysis of these hydrologic time series helps to place current climatic conditions into the perspective of the past 383 years (since 1600). ... The years 1934 and 1959 were the first and fourth driest while 1934 had the lowest July Palmer Drought Severity Index (PDSI) of the reconstructed records. Nevertheless, the decade of the 1930's is only the seventh driest since 1600; the decade 1953-1962 ranks as the second driest. The driest non-overlapping decade since 1600 was 1856-1865. Interestingly, the second wettest decade was 1932-1941. An examination of 30-year mean precipitation data shows that the driest 30-year period was 1871-1900; 1931-1960 ranks as the fourth driest. The current 30-year period (1951-1980) ranks twelfth.

400 years of precipitation variability in central and southern California reconstructed from tree-rings [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Precipitation variability at 31 stations hanging from San Diego to San Francisco and from the coast to the Sierras was characterized ...

Variations in northeast Asian environments over the last 350,000 years reconstructed from pollen records from the northwest Pacific Ocean

EXTRACT (SEE PDF FOR FULL ABSTRACT): Recent analyses of terrestrial (pollen) and marine microfossils (foraminifera and radiolaria) in cores V28-204 and RC14-99 from the northwest Pacific Ocean extend the continuous, chronostratigraphically-controlled records of the regional vegetation of the Pacific coast of Japan and offshore marine environments through three full glacial cycles. The high-resolution pollen time series show systematic relationships between fluctuations in Japanese vegetation and global ice volume over the last 350 kyr. ... Comparison with solar insolation at 30°N and with an index of orbital parameters suggests that variation in northeast Asian summer monsoon intensity is related to orbital forcing.

Late Holocene environmental variability in the upper San Francisco Estuary as reconstructed from tidal marsh sediments

EXTRACT (SEE PDF FOR FULL ABSTRACT): Tidal marsh sediments collected from Browns Island in the lower Sacramento/San Joaquin Delta, California, are used to reconstruct environmental variability over the past 6.8 ka. Calibrated radiocarbon dates provide chronostratigraphic control. Trace metal analyses, grain-size variability, organic content, and macrofossils are used to define short- and long-term variations in relative salinity and inundation frequency. Aggradation began in subtidal fresh water conditions about 6.8 ka. Subtidal aggradation of clayey silts continued until about 6.3 ka, when conditions shifted toward a lower intertidal brackish marsh environment. By 5.1 ka, a brackish marsh plain had evolved, with surface water freshening after 4.1 ka. Conditions returned to brackish similar to the present after 2.3 ka.