Publications Published in 1999

1. A comparison of systems for measuring methane emissions from sheep. Murray, P J; Moss, A; Lockyer, D R; Jarvis, S C.
   Journal of Agriculture Science: 1999
   Notes
   Two experiments were conducted, at ADAS Drayton in the autumn and winter 1996/1997, to compare methane (CH4) emissions from sheep housed either in a polytunnel system or in open-circuit respiration chambers. In each system, the sheep received maintenance levels of either cut grass or high temperature dried grass pellets (HTDG). All experiments in the tunnel were conducted on concrete to avoid any interactions of the CH4 with the soil/plant environment. The results suggested that CH4 production from the open-circuit chambers was greater than from the tunnel system (26·9±0·46 v. 31·7±0·35 l/kg dry matter intake (±S.E.) for open circuit respiration chambers and tunnel, respectively). Recovery tests gave similar results for both systems (95·5–97·9% for tunnels and 89·2–96·7% for chambers), and confirmed that both methods give good quantitative recovery of added CH4, and can therefore be assumed to provide reliable estimates of emissions from animals. There is no technical explanation, therefore, for the different estimates of emissions provided by the two systems. Further studies are required to understand the reasons for the differences and in particular, the possible links between animal behavior induced by the two systems and CH4 emission rates.
   
   
   
2. Analysis of ozone in the San Joaquin Valley of California. Dabdub, Donald; DeHaan, Laurel L; Seinfeld, John H.
   Atmospheric Environment: 1999
   Notes
   The dynamics of ozone in the San Joaquin Valley of central California are studied by systematic diagnostic runs of the three-dimensional SARMAP Air Quality Model. Air quality in the San Joaquin Valley is the result of a complex combination of local and transported emissions. Simulations show that relatively brisk winds at points of inflow to the Valley produce a strong dependence of ozone in the Valley on upwind conditions. Furthermore, NOx influx from boundaries and local emissions has significantly greater impact on ozone production than ROG influx and emissions.
   
   
   
3. A test of basin-scale acoustic thermometry using a large-aperture vertical array at 3250-km range in the eastern North Pacific Ocean. Worcester, P. F.; Cornuelle, B. D.; Dzieciuch, M. A.; Munk, W. H.; Howe, B. M.; Mercer, J. A.; Spindel, R. C.; Colosi, J. A.; Metzger, K.; Birdsall, T. G.; Baggeroer, A. B..
   Journal of the Acoustical Society of America: 1999
   Notes
   Broadband acoustic signals were transmitted during November 1994 from a 75-Hz source suspended near the depth of the sound-channel axis to a 700-m long vertical receiving array approximately 3250 km distant in the eastern North Pacific Ocean. The early part of the arrival pattern consists of raylike wave fronts that are resolvable, identifiable, and stable. The later part of the arrival pattern does not contain identifiable raylike arrivals, due to scattering from internal- wave-induced sound-speed fluctuations. The observed ray travel times differ from ray predictions based on the sound-speed field constructed using nearly concurrent temperature and salinity measurements by more than a priori variability estimates, suggesting that the equation used to compute sound speed requires refinement.
   
   
   
4. A UK inventory of nitrous oxide emissions from farmed livestock. Chadwick, D. R.; Sneath, R. W.; Phillips, V. R.; Pain, B. F..
   Atmospheric Environment: 1999
   Notes
   A UK inventory of the nitrous oxide (N2O) emissions from farmed livestock was compiled to identify areas where potential abatement practices may be effective. Where possible, emission factors based on direct experimental data gathered under UK conditions were used, but published data were used when this was not feasible, together with statistical information, which included details of numbers of animals within each category of a species, animal liveweights, number of days housed, excretal rates and volumes of manures in stores. Total N2O emissions were calculated for each component of livestock production systems, i.e. animal houses, manure stores, following application of manures to land and during grazing. Emissions were also estimated from land used for forage conservation and tillage. Total annual N2O emissions from UK farmed livestock, based mainly on 1996 animal census data, were estimated to be 38.27 kt. The two main terms were 22.66 kt N2O from mineral fertilisers after application to soils and 5.61 kt N2O from stored manures (mainly in the form of farmyard manure). Within buildings, poultry were the largest contributors of N2O, 2.97 kt, followed by cattle, 1.62 kt. Within the total emissions from stored manures, cattle were the largest contributors of N2O, 3.58 kt, followed by poultry, 1.86 kt. Dietary manipulation and a move from solid manure based systems to slurry based systems appear to be promising abatement practices.
   
   
   
5. Big El Ninos ride the back of slower climate change. Kerr, Richard A.
   Science: 1999
   Notes
   Discusses factors which contributed to the severe El Nino season in 1997 and 1998. Successful prediction of the season by climate modelers; Research in the "Journal of Climate" regarding the intensification of El Nino by slower cycles of Pacific Ocean warming; Cause of cycles unknown; Use of the Kaplan temperature record; Impact of long-term global warming and decadal variations.
   
   
   
6. Biological response to climate change on a tropical mountain. Pounds, J. Alan; Fogden, Michael P. L.; Campbell, John H..
   Nature: 1999
   Notes
   Recent warming has caused changes in species distribution and abundance1, 2, 3, but the extent of the effects is unclear. Here we investigate whether such changes in highland forests at Monteverde, Costa Rica, are related to the increase in air temperatures that followed a step-like warming of tropical oceans in 1976 (refs4, 5). Twenty of 50 species of anurans (frogs and toads) in a 30-km2 study area, including the locally endemic golden toad (Bufo periglenes), disappeared following synchronous population crashes in 1987 (refs 6–8). Our results indicate that these crashes probably belong to a constellation of demographic changes that have altered communities of birds, reptiles and amphibians in the area and are linked to recent warming. The changes are all associated with patterns of dry-season mist frequency, which is negatively correlated with sea surface temperatures in the equatorial Pacific and has declined dramatically since the mid-1970s. The biological and climatic patterns suggest that atmospheric warming has raised the average altitude at the base of the orographic cloud bank, as predicted by the lifting-cloud-base hypothesis 9,10.
   
   
   
7. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Petit, J R; Jouzel, J; Raynaud, D; Barkov, N I; Barnola, J-M; Basile, I; Bender, M; Chappellaz, J; Davis, M; Delaygue, G; Delmotte, M; Kotlyakov, V M; Legrand, M; Lipenkov, V Y; Lorius, C; PEpin, L; Ritz, C; Saltzman, E; Stievenard, M.
   Nature: 1999
   Notes
   The recent completion of drilling at Vostok station in East Antarctica has allowed the extension of the ice record of atmospheric composition and climate to the past four glacial–interglacial cycles. The succession of changes through each climate cycle and termination was similar, and atmospheric and climate properties oscillated between stable bounds. Interglacial periods differed in temporal evolution and duration. Atmospheric concentrations of carbon dioxide and methane correlate well with Antarctic air-temperature throughout the record. Present-day atmospheric burdens of these two important greenhouse gases seem to have been unprecedented during the past 420,000 years.
   
   
   
8. Climate change and the episodicity of sediment flux of small California rivers. Inman, Douglas L; Jenkins, Scott A.
   The Journal of Geology: 1999
   Notes
   We studied the streamflow and sediment flux characteristics of the 20 largest streams entering the Pacific Ocean along the central and southern California coast, extending for 750 km from Monterey Bay to just south of the U.S./Mexico border. Drainage basins ranged in area from 120 to 10,800 km2, with headwater elevations ranging from 460 to 3770 m. Annual streamflow ranged from 0 to a maximum of m3/yr for the Santa Clara River in 1969, with 9 1#10 an associated suspended sediment flux of ton. Trend analyses confirm that El Nino/Southern Oscilla- 6 46#10 tion–induced climate changes recur on a multidecadal time scale in general agreement with the Pacific/North American climate pattern: a dry climate extending from 1944 to about 1968 and a wet climate extending from about 1969 to the present. The dry period is characterized by consistently low annual river sediment flux. The wet period has a mean annual suspended sediment flux about five times greater, caused by strong El Nino events that produce floodswith an average recurrence of ca. 5 yr. The sediment flux of the rivers during the three major flood years averages 27 times greater than the annual flux during the previous dry climate. The effects of climate change are superimposed on erodibility associated with basin geology. The sediment yield of the faulted, overturned Cenozoic sediments of the Transverse Ranges is many times greater than that of the Coast Ranges and Peninsular Ranges. Thus, the abrupt transition from dry climate to wet climate in 1969 brought a suspended sediment flux of 100 million tons to the ocean edge of the Santa Barbara Channel from the rivers of the Transverse Range, an amount greater than their total flux during the preceding 25-yr dry period. These alternating dry to wet decadal scale changes in climate are natural cycles that have profound effects on fluvial morphology, engineering structures, and the supply of sediment and associated agricultural chemicals to the ocean.
   
   
   
9. Climate-related change in an intertidal community over short and long time scales. Sagarin, R. D.; Barry, J. P.; Gilman, S. E.; Baxter, C. H..
   Ecological Monographs: 1999
   Notes
   Changes in the abundance of macroinvertebrate species documented in a rocky intertidal community between surveys in 1931-1933 and 1993-1996 are consistent with the predicted effects of recent climate warming. We resampled 57 0.84-m(2) plots of an intertidal transect first surveyed by W. G. Hewatt at Hopkins Marine Station (HMS), Pacific Grove, California, between 1931 and 1933. Replicating precisely the location of the plots and methodology used by Hewatt, we documented changes in the abundances of 46 invertebrate species, indicating that this intertidal community changed significantly during the 60 yr between surveys. Changes in abundance were related to geographic ranges of species. Most southern species (10 of 11) increased in abundance, whereas most northern species (5 of 7) decreased. Cosmopolitan species showed no clear trend, with 12 increasing and 16 decreasing. Although Hewatt did not record algal species as thoroughly as invertebrates, we were able to document a massive decline in cover of Pelvetia compressa, a cosmopolitan fucoid alga that is typically more common in the southern part of its range. Shoreline ocean temperature, taken daily at HMS, warmed by 0.79 degrees C during this 60-yr period, with average summer temperatures up to 1.94 degrees C warmer in the 13 yr preceding our study than in the 13 yr preceding Hewatt's. The hypothesis that climatic warming drove the observed range-related community shifts is supported further by historical records and data from other investigators. Several alternative hypotheses to explain changes in the invertebrate community at HMS, including habitat changes, anthropogenic effects, indirect biological interactions, El Nino-Southern Oscillation (ENSO) events, and upwelling are considered to be less important than climate change. Changes in species' abundances over a short period (3 yr) were relatively small compared to large species shifts over 60 yr and were unrelated to geographic range of the species, indicating that short-term population fluctuations play a relatively minor role in the long-term community changes that we observed.
   
   
   
10. Comparison of seven methods for measuring methane flux at a municipal solid waste landfill site. Tregoures, A.; Beneito, A.; Berne, P.; Gonze, M. A.; Sabroux, J. C.; Savanne, D.; Pokryszka, Z.; Tauziede, C.; Cellier, P.; Laville, P.; Milward, R.; Arnaud, A.; Levy, F.; Burkhalter, R..
    Waste Management & Research: 1999
    Notes
    Seven methods were compared to evaluate methane flux densities in an actual municipal solid waste landfill: two accumulation chambers, two micrometeorological techniques (eddy correlation and mass balance methods), two tracer gas methods and an airborne infrared thermography. The comparison took into account scientific, technical and economic aspects.