Thomas P Guilderson
Biographic Data
| ID | 228902 |
|---|---|
| NAME | Thomas P Guilderson |
| GIVEN NAMES | Thomas P |
| FAMILY NAME | Guilderson |
| SIGNATURE | GUILDERSON T P |
| AFFILIATIONS | Lawrence Livermore National Laboratory |
| ORCID | 0000-0001-9371-7059 |
| VERIFIED | Yes |
| TOTAL WORKS | 32 |
| TOTAL CITATIONS | 5574 |
| AUTHOR COUNT | 32 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2000 |
| LATEST PUBLICATION YEAR | 2025 |
| H-INDEX | 12 |
New and old coral radiocarbon records revisited for the subtropical and tropical Atlantic Ocean
Ocean radiocarbon ( 14 C) is a proxy for air-sea exchange, vertical and horizontal mixing, and water mass identification. Here, we present five pre- to post-bomb coral Δ 14 C records from West Flower Garden Bank and Santiaguillo reefs in the Gulf of Mexico, Boca de Medio, and Isla Tortuga near the Cariaco Basin north of Venezuela. To assess basin-wide Δ 14 C variability, we compiled the Atlantic Ocean reef-building surface coral Δ 14 C records (2…
Marine Biogenic Carbonates and Radiocarbon—a Retrospective on Shells and Corals With an Outlook on Challenges and Opportunities
Many organisms living in the ocean create tests, shells, or related physical structures of calcium carbonate (CaCO 3 ). As this is most often from dissolved inorganic carbon, using organisms that create calcium carbonate structures for climate research and dating purposes requires knowledge of the origin of carbon that is incorporated. Here, we give a short overview of research on marine carbonates over the last 60 years, especially that based on…
Global Ocean Radiocarbon Programs
The importance of studying the radiocarbon content of dissolved inorganic carbon (DI 14 C) in the oceans has been recognized for decades. Starting with the GEOSECS program in the 1970s, 14 C sampling has been a part of most global survey programs. Early results were used to study air-sea gas exchange while the more recent results are critical for helping calibrate ocean general circulation models used to study the effects of climate change. Here …
The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)
Radiocarbon ( 14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14 C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth syste…
Assessing fossil fuel CO 2 emissions in California using atmospheric observations and models
Analysis systems incorporating atmospheric observations could provide a powerful tool for validating fossil fuel CO 2 (ffCO 2 ) emissions reported for individual regions, provided that fossil fuel sources can be separated from other CO 2 sources or sinks and atmospheric transport can be accurately accounted for. We quantified ffCO 2 by measuring radiocarbon ( 14 C) in CO 2 , an accurate fossil-carbon tracer, at nine observation sites in Californi…
Results from the first intensive dating program for pigment art in the Australian arid zone
IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP
The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14 C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were r…
SHCal13 Southern Hemisphere Calibration, 0–50,000 Years cal BP
The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correla…
Allocation of Terrestrial Carbon Sources Using 14 CO 2
The radiocarbon content of whole air provides a theoretically ideal and now observationally proven tracer for recently added fossil-fuel-derived CO 2 in the atmosphere ( C ff ). Over large industrialized land areas, determination of C ff also constrains the change in CO 2 due to uptake and release by the terrestrial biosphere. Here, we review the development of a Δ 14 CO 2 measurement program and its implementation within the US portion of the NO…
Selection and Treatment of Data for Radiocarbon Calibration
High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon calibration curves. We discuss here the basic assumptions behind 14 C dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are obtained. We also highlight the procedures, problems, and uncertainties involved in determining atmospheric and surface ocean 14 C/ 12 C in these archives, i…
Measuring Submicron-Size Fractionated Particulate Matter on Aluminum Impactor Disks
Submicron-sized airborne particulate matter (PM) is not collected well on regular quartz or glass fiber filter papers. We used a micro-orifice uniform deposit impactor (MOUDI) to fractionate PM into 6 size fractions and deposit it on specially designed high-purity thin aluminum disks. The MOUDI separated PM into fractions 56–100, 100–180, 180–320, 320–560, 560–1000, and 1000–1800 nm. Since the MOUDI has a low flow rate (30 L/min), it takes severa…
The Transition to Agriculture at Dadiwan, People's Republic of China
Recent excavations at the Dadiwan site in the western Loess Plateau, Gansu Province, People's Republic of China (PRC), document the first continuous foraging-to-farming sequence in North China. The Dadiwan occupation began at about 80,000 BP and became regular by about 60,000 BP, probably before the arrival or evolution of modern Homo sapiens in North China. This record spans the transitions from nonintensive to intensive hunting and gathering an…
Climate and vegetation history from a 14,000-year peatland record, Kenai Peninsula, Alaska
Analysis of pollen, spores, macrofossils, and lithology of an AMS 14 C-dated core from a subarctic fen on the Kenai Peninsula, Alaska reveals changes in vegetation and climate beginning 14,200 cal yr BP. Betula expansion and contraction of herb tundra vegetation characterize the Younger Dryas on the Kenai, suggesting increased winter snowfall concurrent with cool, sunny summers. Remarkable Polypodiaceae (fern) abundance between 11,500 and 8500 ca…
Agricultural origins and the isotopic identity of domestication in northern China
Stable isotope biochemistry (δ 13 C and δ 15 N) and radiocarbon dating of ancient human and animal bone document 2 distinct phases of plant and animal domestication at the Dadiwan site in northwest China. The first was brief and nonintensive: at various times between 7900 and 7200 calendar years before present (calBP) people harvested and stored enough broomcorn millet ( Panicum miliaceum ) to provision themselves and their hunting dogs ( Canis s…
Pre-Bomb Surface Water Radiocarbon of the Gulf of Mexico and Caribbean as Recorded in Hermatypic Corals
Radiocarbon measurements of hermatypic corals from 4 sites in the Gulf of Mexico (GOM) and Caribbean Sea were made to estimate the marine 14 C reservoir age (R) and the marine regional correction (ΔR) for this region. Coral skeletal material from the Flower Garden Banks (northern GOM continental shelf), Veracruz, Mexico, and 2 reefs from the Cariaco Basin, Venezuela, were analyzed. Annual and subannual samples from 1945–1955 were milled and 14 C …
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years cal BP
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves…
Methods for High-Precision 14 C AMS Measurement of Atmospheric CO 2 at LLNL
Development of radiocarbon analysis with precision better than 2% has the potential to expand the utility of 14 CO 2 measurements for carbon cycle investigations as atmospheric gradients currently approach the typical measurement precision of 2–5%. The accelerator mass spectrometer at Lawrence Livermore National Laboratory (LLNL) produces high and stable beam currents that enable efficient acquisition times for large numbers of 14 C counts. One m…
Lower Pecos and Coahuila peyote
Seawater Radiocarbon Evolution in the Gulf of Alaska
Oceanic uptake and transport of bomb radiocarbon as 14 CO 2 created by atmospheric nuclear weapons testing in the 1950s and 1960s has been a useful diagnostic for determining the carbon transfer between the ocean and atmosphere. In addition, the distribution of 14 C in the ocean can be used as a tracer of oceanic circulation. Results obtained on samples collected in the Gulf of Alaska in the summer of 2002 provide a direct comparison with results…
Climate change on the Yucatan Peninsula during the Little Ice Age
We studied a 5.1-m sediment core from Aguada X'caamal (20° 36.6′N, 89° 42.9′W), a small sinkhole lake in northwest Yucatan, Mexico. Between 1400 and 1500 A.D., oxygen isotope ratios of ostracod and gastropod carbonate increased by an average of 2.2‰ and the benthic foraminifer Ammonia beccarii parkinsoniana appeared in the sediment profile, indicating a hydrologic change that included increased lake water salinity. Pollen from a core in nearby Ce…
Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals
Pre-Bomb Δ 14 C Variability and the Suess Effect in Cariaco Basin Surface Waters as Recorded in Hermatypic Corals
The Δ 14 C content of surface waters in and around the Cariaco Basin was reconstructed from radiocarbon measurements on sub-annually sampled coral skeletal material. During the late 1930s to early 1940s, surface waters within and outside of the Cariaco Basin were similar. Within the Cariaco Basin at Islas Tortugas, coral Δ 14 C averages −51.9 ± 3.3%. Corals collected outside of the basin at Boca de Medio and Los Testigos have Δ 14 C values of −53…
Direct radiocarbon dating of megalithic paints from north-west Iberia
Using plasma chemistry, carbon was extracted from charcoal paint samples collected from megalithic monuments in north-west Iberia. Nine accelerator mass spectrometric radiocarbon dates on these paints establish their age to be within 1000 14C years of each other, centred at approximately 5000 BP. These radiocarbon ages for megalithic paintings fall within the proposed time period for north-west Iberian megalithic culture. Multiple layers of paint…
Dietary reconstruction of an early to middle Holocene human population from the central California coast
Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP
A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0–26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period f…
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years cal BP
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves…
IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP
The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14 C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were r…
Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP
A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0–26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period f…
The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)
Radiocarbon ( 14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14 C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth syste…
SHCal13 Southern Hemisphere Calibration, 0–50,000 Years cal BP
The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correla…
Marine04 Marine Radiocarbon Age Calibration, 0–26 Cal Kyr Bp
New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision, and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically-dated tree-ring…
Dietary reconstruction of an early to middle Holocene human population from the central California coast
The Transition to Agriculture at Dadiwan, People's Republic of China
Recent excavations at the Dadiwan site in the western Loess Plateau, Gansu Province, People's Republic of China (PRC), document the first continuous foraging-to-farming sequence in North China. The Dadiwan occupation began at about 80,000 BP and became regular by about 60,000 BP, probably before the arrival or evolution of modern Homo sapiens in North China. This record spans the transitions from nonintensive to intensive hunting and gathering an…
Selection and Treatment of Data for Radiocarbon Calibration
High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon calibration curves. We discuss here the basic assumptions behind 14 C dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are obtained. We also highlight the procedures, problems, and uncertainties involved in determining atmospheric and surface ocean 14 C/ 12 C in these archives, i…
Southwest Subtropical Pacific Surface Water Radiocarbon in a High-Resolution Coral Record
We have generated a high-resolution coral Δ 14 C record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950–1956) Δ 14 C values average −52%. Values begin to increase in 1957, reaching a maximum in the early 1970s, about 10 yr after the atmospheric peak. There is a consistent 10–15% seasonal cycle whose relationship with vertical mixing evolves as a consequence of the penetration of the bomb transient into subsurface wat…
Results from the first intensive dating program for pigment art in the Australian arid zone
Lower Pecos and Coahuila peyote
Direct radiocarbon dating of megalithic paints from north-west Iberia
Using plasma chemistry, carbon was extracted from charcoal paint samples collected from megalithic monuments in north-west Iberia. Nine accelerator mass spectrometric radiocarbon dates on these paints establish their age to be within 1000 14C years of each other, centred at approximately 5000 BP. These radiocarbon ages for megalithic paintings fall within the proposed time period for north-west Iberian megalithic culture. Multiple layers of paint…
Preliminary Report of the First Workshop of the Intcal04 Radiocarbon Calibration/Comparison Working Group
The first meeting of the IntCal04 working group took place at Queen's University Belfast from April 15 to 17, 2002. The participants are listed as co-authors of this report. The meeting considered criteria for the acceptance of data into the next official calibration dataset, the importance of including reliable estimates of uncertainty in both the radiocarbon ages and the cal ages, and potential methods for combining datasets. This preliminary r…
Methods for High-Precision 14 C AMS Measurement of Atmospheric CO 2 at LLNL
Development of radiocarbon analysis with precision better than 2% has the potential to expand the utility of 14 CO 2 measurements for carbon cycle investigations as atmospheric gradients currently approach the typical measurement precision of 2–5%. The accelerator mass spectrometer at Lawrence Livermore National Laboratory (LLNL) produces high and stable beam currents that enable efficient acquisition times for large numbers of 14 C counts. One m…
Pre-Bomb Surface Water Radiocarbon of the Gulf of Mexico and Caribbean as Recorded in Hermatypic Corals
Radiocarbon measurements of hermatypic corals from 4 sites in the Gulf of Mexico (GOM) and Caribbean Sea were made to estimate the marine 14 C reservoir age (R) and the marine regional correction (ΔR) for this region. Coral skeletal material from the Flower Garden Banks (northern GOM continental shelf), Veracruz, Mexico, and 2 reefs from the Cariaco Basin, Venezuela, were analyzed. Annual and subannual samples from 1945–1955 were milled and 14 C …
Pre-Bomb Δ 14 C Variability and the Suess Effect in Cariaco Basin Surface Waters as Recorded in Hermatypic Corals
The Δ 14 C content of surface waters in and around the Cariaco Basin was reconstructed from radiocarbon measurements on sub-annually sampled coral skeletal material. During the late 1930s to early 1940s, surface waters within and outside of the Cariaco Basin were similar. Within the Cariaco Basin at Islas Tortugas, coral Δ 14 C averages −51.9 ± 3.3%. Corals collected outside of the basin at Boca de Medio and Los Testigos have Δ 14 C values of −53…
Seawater Radiocarbon Evolution in the Gulf of Alaska
Oceanic uptake and transport of bomb radiocarbon as 14 CO 2 created by atmospheric nuclear weapons testing in the 1950s and 1960s has been a useful diagnostic for determining the carbon transfer between the ocean and atmosphere. In addition, the distribution of 14 C in the ocean can be used as a tracer of oceanic circulation. Results obtained on samples collected in the Gulf of Alaska in the summer of 2002 provide a direct comparison with results…
High-Precision AMS 14 C Results on Tiri/Firi Turbidite
Unleached aliquots of TIRI/FIRI turbidite were analyzed by accelerator mass spectronomy (AMS) over a timespan of 18 months. Individual analyses ranged from 18,090–18,245 yr BP with reported errors between 30–50 yr. The weighted average fraction modern (FM) of these 28 measurements is 0.10378 ± 0.00008 (which equates to 18,199 ± 8 yr BP) and the measurements show a 1 standard deviation scatter of 0.00044 (±35 yr). The fractional error of these res…
Global Ocean Radiocarbon Programs
The importance of studying the radiocarbon content of dissolved inorganic carbon (DI 14 C) in the oceans has been recognized for decades. Starting with the GEOSECS program in the 1970s, 14 C sampling has been a part of most global survey programs. Early results were used to study air-sea gas exchange while the more recent results are critical for helping calibrate ocean general circulation models used to study the effects of climate change. Here …
Marine Biogenic Carbonates and Radiocarbon—a Retrospective on Shells and Corals With an Outlook on Challenges and Opportunities
Many organisms living in the ocean create tests, shells, or related physical structures of calcium carbonate (CaCO 3 ). As this is most often from dissolved inorganic carbon, using organisms that create calcium carbonate structures for climate research and dating purposes requires knowledge of the origin of carbon that is incorporated. Here, we give a short overview of research on marine carbonates over the last 60 years, especially that based on…
Allocation of Terrestrial Carbon Sources Using 14 CO 2
The radiocarbon content of whole air provides a theoretically ideal and now observationally proven tracer for recently added fossil-fuel-derived CO 2 in the atmosphere ( C ff ). Over large industrialized land areas, determination of C ff also constrains the change in CO 2 due to uptake and release by the terrestrial biosphere. Here, we review the development of a Δ 14 CO 2 measurement program and its implementation within the US portion of the NO…
Pre-Bomb Radiocarbon Variability Inferred from a Kenyan Coral Record
We report results from AMS radiocarbon measurements (δ 14 C) in corals recovered off the coast of Kenya. Bimonthly samples which span the pre-bomb era average −51 (±3.7; n=43), when age and Suess effect are corrected, and over the time of interest (1946–1954) do not exhibit any discernible seasonality. Relative to regional pre-bomb δ 14 C values in the western Indian Ocean, our results indicate 14 C enrichment off the coast of Kenya. Furthermore,…
Southwest Subtropical Pacific Surface Water Radiocarbon in a High-Resolution Coral Record
We have generated a high-resolution coral Δ 14 C record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950–1956) Δ 14 C values average −52%. Values begin to increase in 1957, reaching a maximum in the early 1970s, about 10 yr after the atmospheric peak. There is a consistent 10–15% seasonal cycle whose relationship with vertical mixing evolves as a consequence of the penetration of the bomb transient into subsurface wat…
Solar Forcing of Drought Frequency in the Maya Lowlands
We analyzed lake-sediment cores from the Yucatan Peninsula, Mexico, to reconstruct the climate history of the region over the past 2600 years. Time series analysis of sediment proxies, which are sensitive to the changing ratio of evaporation to precipitation (oxygen isotopes and gypsum precipitation), reveal a recurrent pattern of drought with a dominant periodicity of 208 years. This cycle is similar to the documented 206-year period in records …
A 4000-Year Lacustrine Record of Environmental Change in the Southern Maya Lowlands, Petén, Guatemala
A 4000-yr sediment core record from Lake Salpetén, Guatemala, provides evidence for Maya-induced forest clearance and consequent soil erosion between ∼1700 cal yr B.C. and 850 cal yr A.D. Radiocarbon ages of wood, seeds, and charcoal support an age-depth model with average errors of ±110 cal yr. Relatively low carbonate δ 18 O values between 1300 and 400 cal yr B.C. coincide with pollen evidence for forest loss, consistent with increased surface …
Pre-Bomb Radiocarbon Variability Inferred from a Kenyan Coral Record
We report results from AMS radiocarbon measurements (δ 14 C) in corals recovered off the coast of Kenya. Bimonthly samples which span the pre-bomb era average −51 (±3.7; n=43), when age and Suess effect are corrected, and over the time of interest (1946–1954) do not exhibit any discernible seasonality. Relative to regional pre-bomb δ 14 C values in the western Indian Ocean, our results indicate 14 C enrichment off the coast of Kenya. Furthermore,…
Preliminary Report of the First Workshop of the Intcal04 Radiocarbon Calibration/Comparison Working Group
The first meeting of the IntCal04 working group took place at Queen's University Belfast from April 15 to 17, 2002. The participants are listed as co-authors of this report. The meeting considered criteria for the acceptance of data into the next official calibration dataset, the importance of including reliable estimates of uncertainty in both the radiocarbon ages and the cal ages, and potential methods for combining datasets. This preliminary r…
High-Precision AMS 14 C Results on Tiri/Firi Turbidite
Unleached aliquots of TIRI/FIRI turbidite were analyzed by accelerator mass spectronomy (AMS) over a timespan of 18 months. Individual analyses ranged from 18,090–18,245 yr BP with reported errors between 30–50 yr. The weighted average fraction modern (FM) of these 28 measurements is 0.10378 ± 0.00008 (which equates to 18,199 ± 8 yr BP) and the measurements show a 1 standard deviation scatter of 0.00044 (±35 yr). The fractional error of these res…
Dietary reconstruction of an early to middle Holocene human population from the central California coast
Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP
A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0–26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period f…
Marine04 Marine Radiocarbon Age Calibration, 0–26 Cal Kyr Bp
New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision, and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically-dated tree-ring…
Climate change on the Yucatan Peninsula during the Little Ice Age
We studied a 5.1-m sediment core from Aguada X'caamal (20° 36.6′N, 89° 42.9′W), a small sinkhole lake in northwest Yucatan, Mexico. Between 1400 and 1500 A.D., oxygen isotope ratios of ostracod and gastropod carbonate increased by an average of 2.2‰ and the benthic foraminifer Ammonia beccarii parkinsoniana appeared in the sediment profile, indicating a hydrologic change that included increased lake water salinity. Pollen from a core in nearby Ce…
Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals
Pre-Bomb Δ 14 C Variability and the Suess Effect in Cariaco Basin Surface Waters as Recorded in Hermatypic Corals
The Δ 14 C content of surface waters in and around the Cariaco Basin was reconstructed from radiocarbon measurements on sub-annually sampled coral skeletal material. During the late 1930s to early 1940s, surface waters within and outside of the Cariaco Basin were similar. Within the Cariaco Basin at Islas Tortugas, coral Δ 14 C averages −51.9 ± 3.3%. Corals collected outside of the basin at Boca de Medio and Los Testigos have Δ 14 C values of −53…
Direct radiocarbon dating of megalithic paints from north-west Iberia
Using plasma chemistry, carbon was extracted from charcoal paint samples collected from megalithic monuments in north-west Iberia. Nine accelerator mass spectrometric radiocarbon dates on these paints establish their age to be within 1000 14C years of each other, centred at approximately 5000 BP. These radiocarbon ages for megalithic paintings fall within the proposed time period for north-west Iberian megalithic culture. Multiple layers of paint…
Lower Pecos and Coahuila peyote
Seawater Radiocarbon Evolution in the Gulf of Alaska
Oceanic uptake and transport of bomb radiocarbon as 14 CO 2 created by atmospheric nuclear weapons testing in the 1950s and 1960s has been a useful diagnostic for determining the carbon transfer between the ocean and atmosphere. In addition, the distribution of 14 C in the ocean can be used as a tracer of oceanic circulation. Results obtained on samples collected in the Gulf of Alaska in the summer of 2002 provide a direct comparison with results…
Methods for High-Precision 14 C AMS Measurement of Atmospheric CO 2 at LLNL
Development of radiocarbon analysis with precision better than 2% has the potential to expand the utility of 14 CO 2 measurements for carbon cycle investigations as atmospheric gradients currently approach the typical measurement precision of 2–5%. The accelerator mass spectrometer at Lawrence Livermore National Laboratory (LLNL) produces high and stable beam currents that enable efficient acquisition times for large numbers of 14 C counts. One m…
Climate and vegetation history from a 14,000-year peatland record, Kenai Peninsula, Alaska
Analysis of pollen, spores, macrofossils, and lithology of an AMS 14 C-dated core from a subarctic fen on the Kenai Peninsula, Alaska reveals changes in vegetation and climate beginning 14,200 cal yr BP. Betula expansion and contraction of herb tundra vegetation characterize the Younger Dryas on the Kenai, suggesting increased winter snowfall concurrent with cool, sunny summers. Remarkable Polypodiaceae (fern) abundance between 11,500 and 8500 ca…
Agricultural origins and the isotopic identity of domestication in northern China
Stable isotope biochemistry (δ 13 C and δ 15 N) and radiocarbon dating of ancient human and animal bone document 2 distinct phases of plant and animal domestication at the Dadiwan site in northwest China. The first was brief and nonintensive: at various times between 7900 and 7200 calendar years before present (calBP) people harvested and stored enough broomcorn millet ( Panicum miliaceum ) to provision themselves and their hunting dogs ( Canis s…
Pre-Bomb Surface Water Radiocarbon of the Gulf of Mexico and Caribbean as Recorded in Hermatypic Corals
Radiocarbon measurements of hermatypic corals from 4 sites in the Gulf of Mexico (GOM) and Caribbean Sea were made to estimate the marine 14 C reservoir age (R) and the marine regional correction (ΔR) for this region. Coral skeletal material from the Flower Garden Banks (northern GOM continental shelf), Veracruz, Mexico, and 2 reefs from the Cariaco Basin, Venezuela, were analyzed. Annual and subannual samples from 1945–1955 were milled and 14 C …
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years cal BP
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves…
Measuring Submicron-Size Fractionated Particulate Matter on Aluminum Impactor Disks
Submicron-sized airborne particulate matter (PM) is not collected well on regular quartz or glass fiber filter papers. We used a micro-orifice uniform deposit impactor (MOUDI) to fractionate PM into 6 size fractions and deposit it on specially designed high-purity thin aluminum disks. The MOUDI separated PM into fractions 56–100, 100–180, 180–320, 320–560, 560–1000, and 1000–1800 nm. Since the MOUDI has a low flow rate (30 L/min), it takes severa…
The Transition to Agriculture at Dadiwan, People's Republic of China
Recent excavations at the Dadiwan site in the western Loess Plateau, Gansu Province, People's Republic of China (PRC), document the first continuous foraging-to-farming sequence in North China. The Dadiwan occupation began at about 80,000 BP and became regular by about 60,000 BP, probably before the arrival or evolution of modern Homo sapiens in North China. This record spans the transitions from nonintensive to intensive hunting and gathering an…
IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP
The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14 C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were r…
SHCal13 Southern Hemisphere Calibration, 0–50,000 Years cal BP
The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correla…
Allocation of Terrestrial Carbon Sources Using 14 CO 2
The radiocarbon content of whole air provides a theoretically ideal and now observationally proven tracer for recently added fossil-fuel-derived CO 2 in the atmosphere ( C ff ). Over large industrialized land areas, determination of C ff also constrains the change in CO 2 due to uptake and release by the terrestrial biosphere. Here, we review the development of a Δ 14 CO 2 measurement program and its implementation within the US portion of the NO…
Radiocarbon dating (24 works) · Geography (20 works) · Geology (19 works) · Archaeology and ancient environmental studies (18 works) · Geology and Paleoclimatology Research (18 works) · Paleontology (14 works) · Archaeology (13 works) · Oceanography (12 works) · Physical geography (10 works) · Chemistry (9 works)