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What's New on the Paleo Web Pages - 2000

What's New in 2000:
Synchronous Radiocarbon and Climate Shifts During the Last Deglaciation Hughen et al. Science, v.290, pp 1951-1954, 8 Dec 2000.

Radiocarbon data from the Cariaco Basin provide calibration of the carbon-14 time scale across the period of deglaciation (15,000 to 10,000 years ago) with resolution available previously only from Holocene tree rings. Reconstructed changes in atmospheric carbon-14 are larger than previously thought, with the largest change occurring simultaneously with the sudden climatic cooling of the Younger Dryas event. Carbon-14 and published beryllium-10 data together suggest that concurrent climate and carbon-14 changes were predominantly the result of abrupt shifts in deep ocean ventilation.
A coral oxygen isotope record from the northern Red Sea documenting NAO, ENSO, and North Pacific teleconnections on Middle East climate variability since the year 1750. Felis et al. Paleoceanography, v.15, pp. 679-694, Dec 2000.

A 245-year coral oxygen isotope record from the northern Red Sea suggests for interannual and longer timescales that colder periods are accompanied by more arid conditions in the northern Red Sea but increased rainfall in the southeastern Mediterranean, whereas warmer periods are accompanied by decreased rainfall in the latter and less arid conditions in the northern Red Sea. Interannual to interdecadal variability is correlated with instrumental indices of the North Atlantic Oscillation (NAO), the El Niño- Southern Oscillation (ENSO), and North Pacific climate variability.
Global Temperature Patterns in Past Centuries: An Interactive Presentation
Mann et al. Earth Interactions, 4-4, 1-29, 2000.

The recent availability of global networks of annual or seasonal resolution proxy data, combined with the few long instrumental and historical climate records available during the past few centuries, make it possible now to reconstruct annual and seasonal spatial patterns of temperature variation, as well as hemispheric, global-mean, and regional temperature trends, several centuries back in time.
Decadal Sea Surface Temperature Variability in the Sub-Tropical South Pacific from 1726 to 1997 A.D. Linsley et al. Science, v.290, pp. 1145-1148, 10 Nov 2000.

A 271 year record of Sr/Ca variability in a coral from Rarotonga in the South Pacific gyre. Calibration with monthly sea surface temperature (SST) from satellite and ship measurements indicates that this Sr/Ca record is an excellent proxy for SST. The entire Sr/Ca record back to 1726 shows a distinct pattern of decadal variability with repeated decadal and interdecadal SST regime shifts greater than 0.75°C. Comparison with decadal climate variability in the North Pacific as represented by the Pacific Decadal Oscillation index (1900-1997) indicates that several of the largest decadal-scale SST variations at Rarotonga are coherent with SST regime shifts in the North Pacific.
Influence of Mean Climate Change on Climate Variability from a 155-year Tropical Pacific Coral Record. Urban et al. Nature, v.407, pp. 989-993, 26 Oct 2000.

The El Niño/Southern Oscillation (ENSO) system is the primary driver of interannual variability in global climate, but its long-term behavior is poorly understood. A 155-year ENSO reconstruction from a central tropical Pacific coral provides new evidence for long-term changes in the regional mean climate and its variability. Results suggest that variability in the tropical Pacific is linked to the region's mean climate, and that changes in both have occurred during periods of natural as well as anthropogenic climate forcing.
North American Drought: A Paleo Perspective
A comprehensive website on drought in the historical and paleoclimatic records, designed to help educate, inform and highlight the history and importance of drought, and to show how paleoclimate research relates to drought and other important issues of climate variability and change.
Causes of Climate Change Over the Past 1000 Years
Crowley, Science, v.289, pp. 270-277, 14 July 2000.
Recent climate model results and reconstructions of northern hemisphere temperatures and climate forcing over the last 1000 years allow the warming of the 20th century to be placed within a historical context. Removal of all forcing except greenhouse gases from the ~1000 year time series results in a very large late 20th century warming, and provides further evidence that the greenhouse effect has already established itself above the level of natural variability in the climate system. A modeled 21st century global warming projection far exceeds the natural variability of the last 1000 years.
Glacial Lake Hitchcock Varve Data
Rittenour et al, Science, v.288, pp. 1039-1042, 12 May 2000.
A 4000 year glacial varve chronology from New England for 17,500 to 13,500 calendar years before present. The chronology shows a distinct interannual (3 to 5 years) band of enhanced variability suggestive of El Niño-Southern Oscillation (ENSO) teleconnections into North America during the late Pleistocene, when the Laurentide ice sheet was near its maximum extent. This record provides evidence of ENSO-like climate variability during near-peak glacial conditions.
Taylor Dome CO2 Data 62 - 20 KYrBP
Indermühle et al, Geophysical Research Letters, Vol. 27, No. 5, pp. 735-738, 1 March 2000.
A high-resolution 40KYr record of atmospheric CO2 concentration. This record shows four distinct peaks of 20 parts per million by volume (ppmv) on a millennial time scale. Good correlation of the CO2 record with temperature reconstructions based on stable isotope measurements on the Vostok ice core (Antarctica) is found.
Rainfall and Drought in Equatorial East Africa
During the Past 1,100 Years

Verschuren, D., Laird, K., and Cumming, B.  Published January 27, 2000, Nature, Vol. 403.
A decade-scale reconstruction of rainfall and drought in equatorial east Africa over the past 1,100 years, based on lake-level and salinity fluctuations of Lake Naivasha (Kenya). Data indicate equatorial east Africa has alternated between contrasting climate conditions, with significantly drier climate than today during the 'Medieval Warm Period'(~AD 1000-1270) and a relatively wet climate during the 'Little Ice Age' (~AD 1270-1850).
Vostok CO2 Data
Hubertus Fischer, Martin Wahlen, Jesse Smith, Derek Mastroianni, and Bruce Deck.
Published in Science, Vol. 283 12 March 1999 pp 1712-1714.
High-resolution records from Antarctic ice cores show that CO2 concentrations increased by 80 to 100 ppmv 600 +/- 400 years after the warming of the last three deglaciations.
Taylor Dome CO2 Data 27 - 11 KYrBP
Jesse Smith, Hubertus Fischer, Martin Wahlen, Derek Mastroianni, and Bruce Deck.
Published in Nature, Vol. 400 pp 248-250.
The most conspicuous feature of the record of past climate contained in polar ice is the rapid warming which occurs after long intervals of gradual cooling. During the last four transitions from glacial to interglacial conditions, ice records indicate that the CO2 concentration of the atmosphere increased by roughly 80 to 100 ppmv.

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3 January 2001