Publications Published in 2002

1. Abrupt Climate Change: Inevitable Surprises. National Research Council,.
   National Academy Press: 2002
   Notes
   Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. For example, roughly half the north Atlantic warming since the last ice age was achieved in only a decade, and it was accompanied by significant climatic changes across most of the globe. Similar events, including local warmings as large as 16°C, occurred repeatedly during the slide into and climb out of the last ice age. Human civilizations arose after those extreme, global ice-age climate jumps. Severe droughts and other regional climate events during the current warm period have shown similar tendencies of abrupt onset and great persistence, often with adverse effects on societies. Abrupt climate changes were especially common when the climate system was being forced to change most rapidly. Thus, greenhouse warming and other human alterations of the earth system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events. The abrupt changes of the past are not fully explained yet, and climate models typically underestimate the size, speed, and extent of those changes. Hence, future abrupt changes cannot be predicted with confidence, and climate surprises are to be expected.
   
   
   
2. Advanced technology paths to global climate stability: Energy for a greenhouse planet. Hoffert, M.I.; Caldeira, K.; Benford, G.; Criswell, D.R.; Green, C.; Herzog, H.; Jain, A.K.; Kheshgi, H.S.; Lackner, K.S.; Lewis, J.S.; Lightfoot, H.D.; Manheimer, W.; Mankins, J.C.; Mauel, M.E.; Perkins, L.J.; Schlesinger, M.E.; Volk, T.; Wigley, T.M.L..
   Science: 2002
   Notes
   Stabilizing the carbon dioxide induced component of climate change is an energy problem. Establishment of a course toward such stabilization will require the development within the coming decades of primary energy sources that do not emit carbon dioxide to the atmosphere, in addition to efforts to reduce end-use energy demand. Mid-century primary power requirements that are free of carbon dioxide emissions could be several times what we now derive from fossil fuels (similar to10(13) watts), even with improvements in energy efficiency. Here we survey possible future energy sources, evaluated for their capability to supply massive amounts of carbon emission free energy and for their potential for large-scale commercialization. Possible candidates for primary energy sources include terrestrial solar and wind energy, solar power satellites, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids, and fossil fuels from which carbon has been sequestered.
   
   
   
3. Aerosol distributions and cloud interactions at a mountaintop laboratory. Lowenthal, Douglas H; Borys, Randolph D; Wetzel, Melanie A.
   Journal of Geophysical Research Atmospheres: 2002
   Notes
   The first measurements of ultrafine (3–10 nm diameter) condensation nuclei concentrations and particle size distributions at Storm Peak Laboratory (3210 MSL) are presented. In-cloud average hourly average ultrafine concentrations peaked at 1608 cm
   
   
   
4. Allele Frequency Shifts in Response to Climate Change and Physiological Consequences of Allozyme Variation in a Montane Insect. Nathan E. Rank; Elizabeth P. Dahlhoff.
   Evolution: 2002
   Notes
   Rapid changes in climate may impose strong selective pressures on organisms. Evolutionary responses to climate change have been observed in natural populations, yet no example has been documented for a metabolic enzyme locus. Furthermore, few studies have linked physiological responses to stress with allozyme genotypic variation. We quantified changes in allele frequency between 1988 and 1996 at three allozyme loci (isocitrate dehydrogenase, Idh; phosphoglucose isomerase, Pgi; and phosphoglucomutase, Pgm) for the leaf beetle Chrysomela aeneicollis in the Bishop Creek region of the Sierra Nevada of California (2900-3300 m). Beetles often experience high daytime (>32?C) and extremely low nighttime (<-5?C) temperatures during summer. Bishop Creek weather station data indicated that conditions were unusually dry before 1988, and that conditions were cool and wet during the years preceding the 1996 collection. We found directional changes in allele frequency at Pgi (11% increase in the Pgi-1 allele), but not at Id or Pgm. We also found that physiological response to thermal extremes depended on Pgi genotype. Pgi 1-1 individuals induced expression of a 70-kD heat shock protein (HSP) at lower temperatures than 1-4 or 4-4 individuals, and 1-1 individuals expressed higher levels of HSP70 after laboratory exposure to temperatures routinely experienced in nature. Survival after nighttime laboratory exposure to subzero temperatures depended on gender, previous exposure to cold, and Pgi genotype. Females expressed higher levels of HSP70 than males after exposure to heat, and recovery by female Pgi 1-1 homozygotes after exposure to cold (-5?C) was significantly better than 1-4 or 4-4 genotypes. These data suggest that the cooler climate of the mid-1990s may have caused an increase in frequency of the Pgi-1 allele, due to a more robust physiological response to cold by Pgi 1-1 and 1-4 genotypes.
   
   
   
5. A Long-Term Hydrologically Based Dataset of Land Surface Fluxes and States for the Conterminous United States. Maurer, E.P.; Wood, A.W.; Adam, J.C.; Lettenmaier, D.P.; Nijssen, B..
   Journal of Climate: 2002
   Notes
   A frequently encountered difficulty in assessing model-predicted land–atmosphere exchanges of moisture and energy is the absence of comprehensive observations to which model predictions can be compared at the spatial and temporal resolutions at which the models operate. Various methods have been used to evaluate the land surface schemes in coupled models, including comparisons of model-predicted evapotranspiration with values derived from atmospheric water balances, comparison of model-predicted energy and radiative fluxes with tower measurements during periods of intensive observations, comparison of model-predicted runoff with observed streamflow, and comparison of model predictions of soil moisture with spatial averages of point observations. While these approaches have provided useful model diagnostic information, the observation-based products used in the comparisons typically are inconsistent with the model variables with which they are compared—for example, observations are for points or areas much smaller than the model spatial resolution, comparisons are restricted to temporal averages, or the spatial scale is large compared to that resolved by the model. Furthermore, none of the datasets available at present allow an evaluation of the interaction of the water balance components over large regions for long periods. In this study, a model-derived dataset of land surface states and fluxes is presented for the conterminous United States and portions of Canada and Mexico. The dataset spans the period 1950–2000, and is at a 3-h time step with a spatial resolution of degree. The data are distinct from reanalysis products in that precipitation is a gridded product derived directly from observations, and both the land surface water and energy budgets balance at every time step. The surface forcings include precipitation and air temperature (both gridded from observations), and derived downward solar and longwave radiation, vapor pressure deficit, and wind. Simulated runoff is shown to match observations quite well over large river basins. On this basis, and given the physically based model parameterizations, it is argued that other terms in the surface water balance (e.g., soil moisture and evapotranspiration) are well represented, at least for the purposes of diagnostic studies such as those in which atmospheric model reanalysis products have been widely used. These characteristics make this dataset useful for a variety of studies, especially where ground observations are lacking.
   
   
   
6. A multi-century perspective of variability in the Pacific Decadal Oscillation: new insights from tree rings and coral. Gedalof, Ze'ev; Mantua, Nathan J; Peterson, David L.
   Geophysical Research Letters: 2002
   Notes
   Annual growth increments from trees and coral heads provide an opportunity to develop proxy records of climatic variability that extend back in time well beyond the earliest instrumental records, and in regions where records have not been kept. Here we combine five published proxy records of North Pacific climatic variability in order to identify the extent to which these records provide a coherent picture of Pacific Basin climatic variability. This composite chronology is well correlated with the Pacific Decadal Oscillation (PDO) index, and provides a better record of PDO variability than any of the constituent chronologies back to 1840. A comparison of these records suggests that the PDO may not have been an important organizing structure in the North Pacific climate system over much of the 19th century, possibly indicating changes in the spatial pattern of sealevel pressure and consequent surface climate patterns of variability over the Americas.
   
   
   
7. Anaerobic methane oxidation in a landfill-leachate plume. Grossman, E. L.; Cifuentes, L. A.; Cozzarelli, I. M..
   Environmental Science & Technology: 2002
   Notes
   The alluvial aquifer adjacent to Norman Landfill, OK, provides an excellent natural laboratory for the study of anaerobic processes impacting landfill-leachate contaminated aquifers. We collected groundwaters from a transect of seven multilevel wells ranging in depth from 1.3 to 11 m that were oriented parallel to the flow path. The center of the leachate plume was characterized by (1) high alkalinity and elevated concentrations of total dissolved organic carbon, reduced iron, and methane, and (2) negligible oxygen, nitrate, and sulfate concentrations. Methane concentrations and stable carbon isotope (delta(13)C) values suggest anaerobic methane oxidation was occurring within the plume and at its margins. Methane delta(13)C values increased from about -54parts per thousand near the source to > -10parts per thousand downgradient and at the plume margins. The isotopic fractionation associated with this methane oxidation was -13.6 +/- 1.0parts per thousand.
   
   
   
8. Analysis of Regional Climate Model Results for simulations of Future Climates. Arritt, R W; Gutowski Jr., W J; Pan, Z; Takle, E S.
   EPRI: 2002
   Notes
   Contemporary global climate models produce results that are too coarse to provide the level of detail required to evaluate environmental, social, and economic impacts of global climate change. High-resolution limited-area models (regional climate models) nested within the global model output have been used to create physically and spatially consistent climates with high spatial resolution. This report evaluates the effectiveness of these models.
   
   
   
9. A new decision sciences for complex systems. Lempert, Robert J.
   Proceedings of the National Academy of Sciences of the United States of America: 2002
   Notes
   Models of complex systems can capture much useful information but can be difficult to apply to real-world decision-making because the type of information they contain is often inconsistent with that required for traditional decision analysis. New approaches, which use inductive reasoning over large ensembles of computational experiments, now make possible systematic comparison of alternative policy options using models of complex systems. This article describes Computer-Assisted Reasoning, an approach to decision-making under conditions of deep uncertainty that is ideally suited to applying complex systems to policy analysis. The article demonstrates the approach on the policy problem of global climate change, with a particular focus on the role of technology policies in a robust, adaptive strategy for greenhouse gas abatement.
   
   
   
10. An integrated model of soil, hydrology, and vegetation for carbon dynamics in wetland ecosystems. Zhang, Yu; Li, Changsheng; Trettin, Carl C; Li, Harbin; Sun, Ge.
    Global Biogeochemical Cycles: 2002
    Notes
    Wetland ecosystems are an important component in global carbon (C) cycles and may exert a large influence on global climate change. Predictions of C dynamics require us to consider interactions among many critical factors of soil, hydrology, and vegetation. However, few such integrated C models exist for wetland ecosystems. We developed a simulation model, Wetland-DNDC, for C dynamics including methane (CH4) emissions in wetland ecosystems. The general structure of the model was adopted from PnET-NDNDC, a process-oriented biogeochemical model that simulates C and N dynamics in upland forest ecosystems. We developed new functions and algorithms to capture the unique features of C dynamics under wetland conditions. Major modifications were made which focus on quantifying water table dynamics, soil thermal dynamics, growth of mosses and herbaceous plants, and soil biogeochemical processes under anaerobic conditions. In this paper, we report new developments made for Wetland-DNDC, as well as tests against observations from three wetland sites in Northern America. Validation results show that the model’s predictions are in good agreement with measurements of water table dynamics, soil temperature, CH4 fluxes, net ecosystem productivity (NEP), and annual C budgets. Sensitivity analysis indicates that the most critical input factors include temperature, water outflow parameters, initial soil C content, and plant photosynthesis capacity. NEP and CH4 emissions are sensitive to many of the input variables required by different components of the model. These results suggest that integrated modeling with soil, hydrology, vegetation, and climate is essential to predict C cycles in wetland ecosystems.