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What's New on the Paleo Web Pages - 2003

What's New in 2003:
East-central China winter temperature reconstruction Winter half-year temperature reconstruction for the middle and lower reaches of the Yellow River and Yangtze River, China, during the past 2000 years.
Ge et al. , Holocene
Volume 13, Issue 6, pp. 933-940, 2003.

Phenological cold/warm events recorded in Chinese historical documents are used to reconstruct, at 10-30 years' resolution, winter half-year (October to April) temperatures for the past 2000 years in the central region of eastern China. From the beginning of the Christian era, climate became cooler at a rate of 0.17°C per century, and around the AD 490s temperature reached about 1°C lower than that of the present (the 1951- 80 mean). Then, abruptly, temperature entered a warm epoch from the AD 570s to 1310s with a warming trend of 0.04°C per century; the peak warming was about 0.3-0.6°C higher than present for 30-year periods, but over 0.9°C warmer on a 10-year basis. After the AD 1310s, temperature decreased rapidly at a rate of 0.10°C per century; the mean temperatures of the four cold troughs were 0.6-0.9°C lower than the present, with the coldest value 1.1°C lower. Temperature has been rising rapidly during the twentieth century, especially for the period 1981-99, and the mean temperature is now 0.5°C higher than for 1951-80. The most interesting aspect over the past 2000 years has been the rapid transitions between cold and warm periods.

Spruce, sedge, and pine distribution at 6,000 years before present. Late Quaternary vegetation dynamics in North America: scaling from taxa to biomes
Williams et al. , Ecological Monographs
Vol. 74, No. 2, pp. 309-334, May 2004.

This paper integrates the mapping of late-Quaternary biomes with palynological evidence for individualistic species responses to environmental change. We document vegetation history in boreal and eastern North America for the past 21,000 calendar years (21 ka), reconstructing past vegetation from fossil pollen evidence at ecological resolutions ranging from individual plant taxa to biomes. At these scales, climatic control of vegetation change is exerted at the level of individual species, from which higher-order properties of the vegetation emerge. Vegetation distribution and composition were relatively stable during full-glacial times (21-17 ka) and the mid- to late Holocene (7-0.5 ka), but changed rapidly during the late glacial and early Holocene (16-8 ka) and after 0.5 ka. Most plant distributions shifted northward, but taxa also moved east or west as, for example, the area of high abundances for spruce, pine, and other cold-tolerants expanded from eastern North America into central and western Canada. Modern associations such as beech-hemlock and spruce-alder-birch date to the early Holocene, whereas other associations common to the late-glacial (e.g. spruce- sedge-ash-hornbeam) no longer exist. Biomes are dynamic entities that have changed in distribution, composition, and structure since the last ice age and before.

Una Paleoperspectiva del Calentamiento Global Spanish Version of Paleo Perspectives and Educational Outreach

The World Data Center for Paleoclimatology's Paleo Perspectives on Global Warming and North American Drought are now available in Spanish. NOAA Paleoclimatology and Dr. Ricardo Villalba of the Centro Regional de Investigaciones Científicas y Tecnológicas (CRICYT) in Mendoza, Argentina oversaw production of the web pages and CRICYT's Maria Elena Soler translated the pages. Co-funded by NOAA Paleoclimatology and the World Data Center System, the translated pages bring the insights of recent paleoclimatological research to a new and important audience. The translations, which also include a primer on paleoclimatology and resources for education and outreach, can be found at the NOAA Paleoclimatology/ World Data Center for Paleoclimatology mirror site in Mendoza.

Testate amoeba from Minden Bog, Michigan A high-resolution record of late-Holocene moisture variability from a Michigan raised bog, USA
Booth and Jackson, Holocene
Volume 13, Issue 6, pp. 863-876, November 2003.

We reconstructed the late-Holocene surface-moisture history and vegetation dynamics of a raised bog in Michigan using testate amoebae, peat humification, pollen, stomata and plant macrofossils. Hydrologic histories inferred from testate amoebae and humification show similar trends, and correspond with records of past water-level variability in Lake Michigan. The bog clearly shows effective-moisture increases during the Algoma highstand (~3200-2300 cal. BP) and a later unnamed highstand (~1900-1300 cal. BP). The good correspondence indicates that bog hydrology and the water levels of Lake Michigan have been driven by changes in large-scale atmospheric circulation patterns for at least the past 3500 years.

Sediment varves from Cariaco Basin core PL07-39PC Synchroneity of Tropical and High-Latitude Atlantic Temperatures over the Last Glacial Termination
Lea et al., Science
Volume 301, Number 5638, pp.1361-1364, 5 September 2003

A high-resolution western tropical Atlantic sea surface temperature (SST) record from the Cariaco Basin on the northern Venezuelan shelf, based on Mg/Ca values in surface-dwelling planktonic foraminifera, reveals that changes in SST over the last glacial termination are synchronous, within ±30 to ±90 years, with the Greenland Ice Sheet Project 2 air temperature proxy record and atmospheric methane record. The most prominent deglacial event in the Cariaco record occurred during the Younger Dryas time interval, when SSTs dropped by 3° to 4°C. A rapid southward shift in the atmospheric intertropical convergence zone could account for the synchroneity of tropical temperature, atmospheric methane, and high-latitude changes during the Younger Dryas.

forest fire photo International Multiproxy Paleofire Database

The International Multiproxy Paleofire Database (IMPD) is a new archive of fire history records, preserved in natural proxies, that has been established to provide a permanent repository for high-quality data from around the world. Fire is an important process in terrestrial ecosystems, modulating the susceptibility of vegetation to climate change, disease, and other disturbances. The growing body of high-quality fire-history data provides opportunities for investigations into the role of fire in ecosystems and the feedbacks that link fire, climate, vegetation, and management decisions. In addition to providing a permanent data repository, the IMPD will allow researchers to compare, combine, and evaluate data from tree scars and charcoal in sediments across temporal and spatial scales. The current data holdings are available at the IMPD web site, and are searchable by various parameters and through an online mapping tool. Paleofire data are also being solicited through online data submission forms via the IMPD web site.

340,000 year d18O and SST Mg/Ca records from core MD97-2120 compared to the Vostok dD record Sea–land oxygen isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implication for paleorainfall during interglacial intervals
Bar-Matthews et al., Geochimica et Cosmochimica Acta
Volume 67, Issue 17, Pages 3181-3199, 1 September 2003.

The oxygen and carbon stable isotope compositions of cave speleothems provide a powerful method for understanding continental climate change. Here, we examine the question of the regionality of this isotopic record and its linkage with the marine isotopic record in the Eastern Mediterranean (EM) region. The study presents a new, accurately dated 250-kyr d18O and d13C record determined from speleothems of the Peqiin Cave, Northern Israel. Its comparison with the continuous 185-kyr isotopic record of the Soreq Cave speleothems from Central Israel reveals striking similarities. Thus, a strong regional climatic signal, brought about by variations in temperature and rainfall amount, is reflected in both cave records. The record for the last 7000 yr shows a trend toward increasing aridity and agrees well with climatic and archeological data from North Africa and the Middle East.

340,000 year d18O and SST Mg/Ca records from core MD97-2120 compared to the Vostok dD record 340,000-Year Centennial-Scale Marine Record of Southern Hemisphere Climatic Oscillation
Pahnke et al., Science
Volume 301, Number 5635, pp. 948-952 (August 15 2003).

In order to investigate rapid climatic changes at mid-southern latitudes, we have developed centennial-scale paleoceanographic records from the southwest Pacific that enable detailed comparison with Antarctic ice core records. These records suggest close coupling of mid-southern latitudes with Antarctic climate during deglacial and interglacial periods. Glacial sections display higher variability than is seen in Antarctic ice cores, which implies climatic decoupling between mid- and high southern latitudes due to enhanced circum-Antarctic circulation. Structural and temporal similarity with the Greenland ice core record is evident in glacial sections and suggests a degree of interhemispheric synchroneity not predicted from bipolar ice core correlations.

Hemispheric temperature reconstructions Global Surface Temperatures over the Past Two Millennia
Mann and Jones, Geophysical Research Letters
Vol. 30, No. 15, 1820 (August 2003)

We present reconstructions of Northern and Southern Hemisphere mean surface temperature over the past two millennia based on high-resolution 'proxy' temperature data which retain millennial-scale variability. These reconstructions indicate that late 20th century warmth is unprecedented for at least roughly the past two millennia for the Northern Hemisphere. Conclusions for the Southern Hemisphere and global mean temperature are limited by the sparseness of available proxy data in the Southern Hemisphere at present.

2650-year (BC665-AD1985) Warm Season Temperature Reconstruction 
spliced with Beijing instrumental data from 1930-2000.  Cyclic rapid warming on centennial-scale revealed by a 2650-year stalagmite record of warm season temperature
Tan et al., Geophysical Research Letters
Vol. 30, No. 12, 1617 (June 2003).

A 2650-year (BC665-AD1985) warm season (MJJA: May, June, July, August) temperature reconstruction is derived from a correlation between thickness variations in annual layers of a stalagmite from Shihua Cave, Beijing, China and instrumental meteorological records. Observations of soil CO2 and drip water suggest that the temperature signal is amplified by the soil-organism-CO2 system and recorded by the annual layer series. Our reconstruction reveals that centennial-scale rapid warming occurred repeatedly following multicentennial cooling trends during the last millennia. These results correlate with different records from the Northern Hemisphere, indicating that the periodic alternation between cool and warm periods on a sub-millennial scale had a sub-hemispherical influence.

4th ICCANE 4th International Congress on the Archaeology of the Ancient Near East
Berlin, March 29-April 3, 2004
Workshop: "Paleoclimate Proxy Data for Holocene East Mediterranean
and West Asia"

This workshop aims to synthesize the proxy data retrieved from ice, lake, marine and speleothem cores across West Asia and adjacent regions to establish coherent (in-phase) and synoptic (simultaneous) sequences of natural Holocene climate stages and abrupt events defined by their precipitation, temperature, seasonality, and other qualities. This synthesis may provide a base-line for building regional prehistoric and ancient agro-production functions and for distinguishing anthropogenic from natural environmental alterations during the period 11.5 - 2 kaBP.

Average global surface air temperature with full forcings. 
 Bottom: 25-year averaged forcing contributions. 
Thin black bars: combined natural forcing (solar + volcanic) A monthly and latitudinally varying volcanic forcing dataset in simulations of 20th century climate
Ammann et al., Geophysical Research Letters
Vol. 30, No. 12, 1657 (June 2003).

A new monthly volcanic forcing dataset is included in a coupled GCM for a more physically consistent treatment of the stratospheric sulfate aerosol history from explosive volcanism. The volcanic forcing is different from previous versions in that there is an individual evolution of the aerosol for each event. Thus the seasonal and latitudinal dependence of the volcanic aerosol can affect global climate in a more realistic way prior to the satellite period, compared to earlier volcanic forcing datasets. Negative radiative forcing from volcanic activity is greatest in the early 20th century prior to 1915 and in the late 20th century after 1960. The combination of volcanic and solar forcing contributes to an early-20th century warming, followed by relative cooling in late 20th century. Consequently, the addition of natural forcing factors to the anthropogenic GHG forcing in late 20th century is required to simulate the observed late 20th century warming.

Fossil coral heads, Palmyra Island El Niño/Southern Oscillation and tropical Pacific climate during the last millennium
Cobb et al., Nature
Vol. 424, No. 6946, pp. 271-276 (17 July 2003)

Any assessment of future climate change requires knowledge of the full range of natural variability in the El Niño/Southern Oscillation (ENSO) phenomenon. Here we splice together fossil-coral oxygen isotopic records from Palmyra Island in the tropical Pacific Ocean to provide 30-150-year windows of tropical Pacific climate variability within the last 1,100 years. The records indicate mean climate conditions in the central tropical Pacific ranging from relatively cool and dry during the tenth century to increasingly warmer and wetter climate in the twentieth century. But the corals also document a broad range of ENSO behaviour that correlates poorly with these estimates of mean climate. The most intense ENSO activity within the reconstruction occurred during the mid-seventeenth century. Taken together, the coral data imply that the majority of ENSO variability over the last millennium may have arisen from dynamics internal to the ENSO system itself.

Reconstructions of warm season AO SAT (top) and SLP index for AD 1650-1975. Tree-ring reconstructions of temperature and sea-level pressure variability associated with the warm-season Arctic Oscillation since AD 1650
D'Arrigo et al., Geophysical Research Letters
Vol. 30, No. 11, 1549 (June 2003)

Arctic Oscillation (AO) changes are inferred from a treering reconstruction of a warm-season temperature index. The reconstruction covers AD1650-1975 and is based largely on chronologies from circumpolar-Arctic and circum-North Atlantic areas. It accounts for 48% of the variance in the instrumental AO record from 1900 to 1975, verifies using independent data, and exhibits its largest variance at low frequencies. Positive levels during 20th century periods equal or exceed values back to AD 1650. Trends (including lower values during "Little Ice Age" periods) resemble those of Arctic temperature reconstructions, reflecting some data overlap, but also the strong link between the AO and northern temperatures. A reconstruction of an AO summer sea level pressure index shows similar trends. Comparison of these reconstructions with proxies of the North Atlantic Oscillation (NAO) and other indices can help clarify relationships between the AO and NAO, at least during the boreal warm season.

Yellowstone Falls from Red Rock Point, NPS photo. Upper Yellowstone River Flow and Teleconnections with Pacific Basin Climate Variability during the Past Three Centuries.
Graumlich et al., Climatic Change
Volume 59, Issue 1-2, pp.245-262, July 2003.

Climate variability, coupled with increasing demand is raising concerns about the sustainability of water resources in the western United States. Tree-ring reconstructions of stream flow that extend the observational record by several centuries provide critical information on the short-term variability and multi-decadal trends in water resources. In this study, precipitation sensitive Douglas-fir (Pseudotsuga menzeisii) tree ring records are used to reconstruct annual flow of the Yellowstone River back to A.D. 1706. Linkages between precipitation in the Greater Yellowstone Region and climate variability in the Pacific basin were incorporated into our model by including indices Pacific Ocean interannual and decadal-scale climatic variability, namely the Pacific Decadal Oscillation and the Southern Oscillation. The reconstruction indicates that 20th century streamflow is not representative of flow during the previous two centuries. With the exception of the 1930s, streamflow during the 20th century exceeded average flows during the previous 200 years. The drought of the 1930s resulted in the lowest flows during the last three centuries, however, this probably does not represent a worst-case scenario for the Yellowstone as other climate reconstructions indicate more extreme droughts prior to the 18th century.

SW Turkey Precip. Recon. Preliminary reconstructions of spring precipitation in southwestern Turkey from tree-ring width
Touchan et al., International Journal of Climatology
Vol. 23, Issue 2, pp. 157-171, February 2003.

Two reconstructions of spring (May-June) precipitation have been developed for southwestern Turkey. Calibration and verification statistics of both reconstructions indicate reasonably accurate reconstruction of spring precipitation, and show clear evidence of multi-year to decadal variations. Apart from the 1476-79 extended dry period, spring droughts of 3 years in length have only occurred from 1700 to the present. The absence of extended spring drought during the 16th and 17th centuries and the occurrence of extended wet spring periods during these centuries suggest a possible regime shift in climate. Preliminary analysis of links between large-scale climatic variation and these climate reconstructions shows that there is a relationship between extremes in spring precipitation and anomalous atmospheric circulation in the region.

Eagle over Nepal Dendroclimatic Signals in Long Tree-Ring Chronologies from the Himalayas of Nepal
Cook et al., International Journal of Climatology
Vol. 23, Issue 7, 707-732, 15 June 2003.

We describe the development of a tree-ring chronology network in Nepal that is suitable for reconstructing temperature-related climate forcing over the past few hundred years. Significant monthly and seasonal temperature responses are identified that provide guidance for the formal reconstruction of two temperature seasons for Kathmandu: February-June (1546-91) and October-February (1605-91). Each reconstruction indicates the occurrence of unusually cold temperatures in 1815-22, which coincides with the eruption of Tambora in Indonesia. A novel method is also used to add probable missing multi-centennial temperature variance to each reconstruction. The resulting adjusted reconstructions strongly reflect patterns of temperature variability associated with Little Ice Age cooling and warming into the 20th century, with the October-February season exhibiting the strongest increase in temperature over the past 400 years. Only the October-February season shows any evidence for late- 20th century warming, whereas February-June temperatures have actually cooled since 1960 (as with the observational series).

Oxygen isotopes from piston core AII-125 JPC-76 Increased northeast Pacific climatic variability during the warm middle Holocene
Friddell et al., Geophysical Research Letters
Vol. 30, No. 11, 1560 (June 2003)

We use a pair of decadally resolved planktonic foraminiferal d18O records from Santa Barbara Basin (SBB) to show that the warmest interval of the current interglacial, the middle Holocene, was characterized by increased decadal- to centennial-scale climatic variability. Modern relationships between the Pacific Decadal Oscillation (PDO), the El Niño-Southern Oscillation (ENSO), and upper water conditions in SBB also suggest a preference of the northeast (NE) Pacific climate during the warm mid-Holocene toward the warm phase of the PDO and more intense ENSO warm events ("El Niño"). In the context of future climate, this study suggests increasing decadal- to centennial-scale climatic variability in a globally warmed world.

Subfossil wood in alluvial deposits of the Yadayakhodyyakha River A continuous multimillennial ring-width chronology in Yamal, northwestern Siberia
Hantemirov and Shiyatov, Holocene
Vol. 12, Issue 6 (December 2002)

Remains of subfossil Siberian larch trees in the Holocene deposits of the Yamal Peninsula (Western Siberia) have been collected in order to develop a continuous, multimillennium tree-ring-width chronology. This work has produced a calendar-age dated 4000-year (2000 BC to AD 1996) series. From these data, summer-temperature variability in this region has been estimated on annual to multidecadal timescales.

Fig. 2 The coral Ba/Ca record of Burdekin River suspended sediment Coral record of increased sediment flux to the inner Great Barrier Reef since European settlement
McCulloch et al., Nature
Vol. 421, 727 - 730 (13 February 2003); doi:10.1038/nature01361.

The effect of European settlement on water quality in the Great Barrier Reef of Australia is a long-standing and controversial issue. Erosion and sediment transport in river catchments in this region have increased substantially since European settlement, but the magnitude of these changes remains uncertain. Here we report analyses of Ba/Ca ratios in long-lived Porites coral from Havannah Reef - a site on the inner Great Barrier Reef that is influenced by flood plumes from the Burdekin river - to establish a record of sediment fluxes from about 1750 to 1998. We find that, in the early part of the record, suspended sediment from river floods reached the inner reef area only occasionally, whereas after about 1870 - following the beginning of European settlement - a five- to tenfold increase in the delivery of sediments is recorded with the highest fluxes occurring during the drought-breaking floods.

Fig. 3  Comparison of Temperature Reconstructions Optimal Surface Temperature Reconstructions Using Terrestrial Borehole Data
Mann et al., Journal of Geophysical Research Atmospheres
Vol. 108 No. D7, 3 April 2003.

We derive an optimal Northern Hemisphere mean surface temperature reconstruction from terrestrial borehole temperature profiles spanning the past five centuries. The pattern of borehole ground surface temperature (GST) reconstructions displays prominent discrepancies with instrumental surface air temperature (SAT) estimates during the 20th century, suggesting the presence of a considerable amount of noise and/or bias in any underlying spatial SAT signal. Application of optimal signal estimation methods yields a hemispheric borehole SAT reconstruction that is largely consistent with instrumental data available in past centuries, and is indistinguishable in its major features from several published long-term temperature estimates based on both climate proxy data and model simulations.


Climate TimeLine Information Tool
The Climate TimeLine Information Tool
Developed as an information resource covering the fundamentals of climate change over varying times scales, the Climate TimeLine Information Tool uses a "powers of 10" exponential or logarithmic approach to look at different time scales. The primary goal of the site is to understand climate of the recent past, and to provide a context and background for framing current and future climate change. This resource includes access to a variety of climate and related environmental data from NOAA and other agencies.

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30 January 2004