What do near-term observations tell us about long-term developments in greenhouse gas emissions?     

Detlef P. van Vuuren  Jae Edmonds  Steven J. Smith  Kate V. Calvin  Joseph Karas  Mikiko Kainuma  Nebojsa Nakicenovic  Keywan Riahi  Bas J. van Ruijven  Rob Swart  Allison Thomson 《Climatic change》2010,103(3-4):635-642

Long-term scenarios developed by integrated assessment models are used in climate research to provide an indication of plausible long-term emissions of greenhouse gases and other radiatively active substances based on developments in the global energy system, land-use and the emissions associated with these systems. The phenomena that determine these long-term developments (several decades or even centuries) are very different than those that operate on a shorter time-scales (a few years). Nevertheless, in the literature, we still often find direct comparisons between short-term observations and long-term developments that do not take into account the differing dynamics over these time scales. In this letter, we discuss some of the differences between the factors that operate in the short term and those that operate in the long term. We use long-term historical emissions trends to show that short-term observations are very poor indicators of long-term future emissions developments. Based on this, we conclude that the performance of long-term scenarios should be evaluated against the appropriate, corresponding long-term variables and trends. The research community may facilitate this by developing appropriate data sets and protocols that can be used to test the performance of long-term scenarios and the models that produce them.  相似文献   

Erratum to “Patterns of accessing variable resources across time and space: Desert plants,animals and people” [J. Arid Environ. 73 (2009) 338–346]     

R.R.J. McAllister  D.M.S. Smith  C.J. Stokes  F.J. Walsh 《Journal of Arid Environments》2009,73(6-7):695

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Geochemical studies of North American soils: Results from the pilot study phase of the North American Soil Geochemical Landscapes Project     

David B. Smith   《Applied Geochemistry》2009,24(8):1355

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Deglacial history of the West Antarctic Ice Sheet in the western Amundsen Sea Embayment     

James A. Smith  Claus-Dieter Hillenbrand  Gerhard Kuhn  Robert D. Larter  Alastair G.C. Graham  Werner Ehrmann  Steven G. Moreton  Matthias Forwick 《Quaternary Science Reviews》2011,30(5-6):488-505

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Reports from the Smithsonian’s Global Volcanism Network, July 2009     

Edward Venzke  Sally Kuhn Sennert  Richard Wunderman 《Bulletin of Volcanology》2010,72(1):129-130

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 34, no. 7, July 2009 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.  相似文献   

Tephrostratigraphy and glass compositions of post-15 kyr Campi Flegrei eruptions: implications for eruption history and chronostratigraphic markers     

V.C. Smith  R. Isaia  N.J.G. Pearce 《Quaternary Science Reviews》2011,30(25-26):3638-3660

Volcanic ash (tephra) erupted from the frequently active Campi Flegrei volcano forms layers in many palaeoenvironmental archives across Italy and the Mediterranean. Proximal deposits of 50 of the post-15 ka eruptions have been thoroughly sampled and analysed to produce a complete database of glass compositions (>1900 analyses) to aid identification of these units. The deposits of individual eruptions are compositionally diverse and this variability is often greater than that observed between different units. Many of the tephra units do not have a unique glass chemistry, with compositionally similar tephra often erupted over long periods of time (1000s years). Thus, glass chemistry alone is not enough to robustly correlate most of the tephra from Campi Flegrei, especially in the last 10 kyrs. In order to reliably correlate the eruption units it is important to take into account the stratigraphy, chronology, magnitude, and dispersal of the eruptions, which has been collated to aid identification. An updated chronology is also presented, which was constrained using Bayesian analysis (OxCal) of published radiocarbon dates and ⁴⁰Ar/³⁹Ar ages. All the data presented can be employed to help correlate post-15 ka tephra units preserved in archaeological and Holocene palaeoenvironmental archives. The new database of proximal glass compositions has been used to correlate proximal volcanic deposits through to distal tephra layers in the Lago di Monticchio record (Wulf et al., 2004, Wulf et al., 2008) and these correlations provide information on eruption stratigraphy and the tempo of volcanism at Campi Flegrei.  相似文献   

Development and deployment of a deep-sea Raman probe for measurement of pore water geochemistry     

Xin Zhang  Peter M. Walz  William J. Kirkwood  Keith C. Hester  William Ussler  Edward T. Peltzer  Peter G. Brewer 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(2):297-306

We have developed, deployed, and tested a novel probe for study of the geochemistry of sediment pore waters based upon Raman spectroscopy. The Raman technique has already been used successfully for in situ measurements of targets of scientific interest including gas and hydrothermal vents and complex gas hydrates, but sediment geochemistry has so far been an intractable problem since the sediments themselves are strongly fluorescent and typically only very small sample volumes are obtainable. The 35 cm long probe extracts pore fluids through a 10 μm sintered metallic frit and draws the sample through a 2 mm diameter channel into a sapphire windowed optical cell within which the laser beam is focused and the spectrum recorded. The dead volume of the system is ～1 ml and the instrument is ROV deployable with activation of probe insertion and sample withdrawal under direct operator control. The unique features of this mode of detection include observation of the sulfate gradient in marine pore waters as an indicator of diagenesis, direct measurement of the dissolved sulfide species H₂S and HS^?, and measurement of dissolved methane; all of which are of primary geochemical interest. Quantitative analysis is achieved by area ratio to known water peaks and from standard calibration curves with a precision of ±5%. We find only very small fluorescence from pore waters measured in situ, but observe rapid increases in fluorescence from cores returned to the surface and exposed to oxygen.  相似文献   

Reports from the Smithsonian’s Global Volcanism Network, February 2010     

Edward Venzke  Sally Kuhn Sennert  Richard Wunderman  Catie Carter 《Bulletin of Volcanology》2010,72(6):769-770

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 35, no. 2, February 2010 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.  相似文献   

Pb-concentrations and Pb-isotope ratios in soils collected along an east–west transect across the United States     

Clemens Reimann  David B. Smith  Laurel G. Woodruff  Belinda Flem 《Applied Geochemistry》2011,26(9-10):1623-1631

Analytical results for Pb-concentrations and isotopic ratios from ca. 150 samples of soil A horizon and ca. 145 samples of soil C horizon collected along a 4000-km east–west transect across the USA are presented. Lead concentrations along the transect show: (1) generally higher values in the soil A-horizon than the C-horizon (median 21 vs. 16.5 mg/kg), (2) an increase in the median value of the soil A-horizon for central to eastern USA (Missouri to Maryland) when compared to the western USA (California to Kansas) (median 26 vs. 20 mg/kg) and (3) a higher A/C ratio for the central to eastern USA (1.35 vs. 1.14). Lead isotopes show a distinct trend across the USA, with the highest ²⁰⁶Pb/²⁰⁷Pb ratios occurring in the centre (Missouri, median A-horizon: 1.245; C-horizon: 1.251) and the lowest at both coasts (e.g., California, median A-horizon: 1.195; C-horizon: 1.216). The soil C-horizon samples show generally higher ²⁰⁶Pb/²⁰⁷Pb ratios than the A-horizon (median C-horizon: 1.224; A-horizon: 1.219). The ²⁰⁶Pb/²⁰⁷Pb-isotope ratios in the soil A horizon show a correlation with the total feldspar content for the same 2500-km portion of the transect from east-central Colorado to the Atlantic coast that shows steadily increasing precipitation. No such correlation exists in the soil C horizon. The data demonstrate the importance of climate and weathering on both Pb-concentration and ²⁰⁶Pb/²⁰⁷Pb-isotope ratios in soil samples and natural shifts thereof in the soil profile during soil-forming processes.  相似文献   

The RAVE survey: constraining the local Galactic escape speed     

Martin C. Smith  Gregory R. Ruchti  Amina Helmi  Rosemary F. G. Wyse  J. P. Fulbright  K. C. Freeman  J. F. Navarro  G. M. Seabroke  M. Steinmetz  M. Williams  O. Bienaymé  J. Binney  J. Bland-Hawthorn  W. Dehnen  B. K. Gibson  G. Gilmore  E. K. Grebel  U. Munari  Q. A. Parker  R.-D. Scholz  A. Siebert  F. G. Watson  T. Zwitter 《Monthly notices of the Royal Astronomical Society》2007,379(2):755-772

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