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871.
Teresa A. Myers Matthew C. Nisbet Edward W. Maibach Anthony A. Leiserowitz 《Climatic change》2012,113(3-4):1105-1112
Communication researchers and practitioners have suggested that framing climate change in terms of public health and/or national security may make climate change more personally relevant and emotionally engaging to segments of the public who are currently disengaged or even dismissive of the issue. To evaluate these assumptions, using a nationally representative online survey of U.S. residents (N?=?1,127) conducted in December, 2010, we randomly assigned six previously identified audience segments on climate change to one of three experimental conditions. Subjects were asked to read uniquely framed news articles about climate change emphasizing either the risks to the environment, public health, or national security and the benefits of mitigation and adaptation-related actions. Results show that across audience segments, the public health focus was the most likely to elicit emotional reactions consistent with support for climate change mitigation and adaptation. Findings also indicated that the national security frame may possibly boomerang among audience segments already doubtful or dismissive of the issue, eliciting unintended feelings of anger. 相似文献
872.
Planktonic larvae of estuarine species often develop in the coastal ocean and return to estuaries using favorable currents.
This study investigated spatial distributions of brachyuran crab post-larvae during ingress to the Newport River estuary,
North Carolina, USA (34°41′ N, 76°40′ W). Nearshore plankton tows were conducted across the inlet to the estuary. Settlement
on passive ‘hog’s hair’ collectors was simultaneously monitored in each of four estuarine channels. Callinectes sapidus density was highest east of the inlet, whereas relative estuarine abundance was higher in western channels. In separate sampling
with collectors at coastal and estuarine locations, spatial distributions of post-larvae were consistent through time but
differed for C. sapidus, Uca spp., and Pachygrapsus transversus. The diel timing of C. sapidus settlement on collectors was determined at the coast and compared to previous studies of settlement in the estuary. Behavioral
responses to environmental cues may alter transport pathways from those predicted by hydrodynamic models. 相似文献
873.
We have measured both P- and S-wave velocities (Vp and Vs) and Poisson's ratios (υ) of 60 typical ultrahigh pressure (UHP) metamorphic rock samples from the Chinese Continental Scientific Drilling (CCSD) main and pre-pilot holes and surface outcrops in the Sulu–Dabie orogenic belt at hydrostatic confining pressures up to 850 MPa. The experimental results, together with those compiled in Handbook of Seismic Properties of Minerals, Rocks and Ores [ Ji, S.C., Wang, Q., Xia, B., 2002. Handbook of Seismic Properties of Minerals, Rocks and Ores. Polytechnic International Press, Montreal, 630 pp.], reveal that except for monomineralic rocks such as quartzite, serpentinite, anorthosite, limestone, and marble the rest of the rock types have Poisson's ratios falling along an upward convex curve determined from the correlations between elastic moduli and density. Poisson's ratios increase with density as the lithology changes from granite, felsic gneiss and schist, through diorite–syenite, intermediate gneiss and metasediment, to gabbro–diabase, amphibolite, and mafic gneiss, and then decrease as the rocks become ultramafic in composition. Eclogite has a higher density but a lower Poisson's ratio than peridotite. The results were applied to constrain the crustal composition and tectonic evolution of the Chinese continental crust based on crustal thickness (H) and Poisson's ratio (υ) from 248 broadband seismic stations, measured using teleseismic receiver function techniques. The North China, Yangtze, South China and Northeast China blocks and Songpan–Ganzi Terrane are dominated by low (υ < 0.26) and moderate (0.26 ≤ υ < 0.28) υ values (> 70%), suggesting the dominance of felsic composition in the crust. The Lhasa terrane, Qiangtang terrane, and Indochina block are characterized by high proportions (33–42%) of measurements with very high υ values (≥ 0.30 and H is found for the South China block, Northeast block, Lhasa block, Qiangtang terrane and Indochina block, indicating either tectonic thickening of the felsic upper and middle crust by folding and thrusting or the removal of mafic layers from the lower crust into the upper mantle by delamination. 相似文献
874.
Martin Reich Carlos Palacios Gabriel Vargas Shangde Luo Eion M. Cameron Matthew I. Leybourne Miguel A. Parada Alejandro Zúñiga Cheng-Feng You 《Mineralium Deposita》2009,44(5):497-504
Supergene enrichment of Cu deposits in the Atacama Desert has played a critical role in making this the prime Cu-producing
province of the world. Previously, this has been believed to have occurred exclusively over a long period from the middle
Eocene to the late Miocene, which ended when climatic conditions changed from arid to hyperarid. Here, we report U-series
disequilibrium ages in atacamite-bearing supergene assemblages that provide a new conceptualization on both the supergene
enrichment process and the onset of extreme hyperaridity in the Atacama Desert. 230Th–234U ages of gypsum intergrown with atacamite in supergene veins from Cu deposits cluster at ~240 ka (Chuquicamata), 130 ka (Mantos
Blancos, Spence), and 80 ka (Mantos de la Luna, Michilla). When coupled with previous data, these results indicate that supergene
enrichment of Cu deposits did not cease after the onset of hyperaridity. We propose that supergene enrichment in the Atacama
region developed in two main stages. The main phase, caused by downward circulation of meteoric waters in a semi-arid setting,
was active from 45 until ~9 Ma, with a last pulse ca. 5 Ma in the southern Atacama Desert. During this phase, atacamite-bearing
supergene assemblages were not preserved because atacamite requires saline water for its formation and rapidly dissolves when
contacted by meteoric water. This was followed by a second stage starting at ~2–1.5 Ma and continuing until at least the late
Pleistocene, when deep formation waters derived from the basement passed up through and modified the pre-existing supergene
Cu oxide minerals. Atacamite has then been preserved in the prevailing hyperarid climate. 相似文献
875.
Coprolites can provide detailed information about the nutritional habits and digestive processes of the animals that produced them and may also yield information about the palaeoenvironment in which the animal existed. To test the utility of the lipid biomarker approach to coprolite analysis, lipids were extracted from a coprolite of the Pleistocene ground sloth Nothrotheriops shastensis. Gas chromatography/mass spectrometry results revealed a dominant spiroketal sapogenin component identified, using nuclear magnetic resonance spectroscopy, as epismilagenin. The dominance of epismilagenin is probably due to ingestion of Yucca spp. and Agave spp., which is consistent with previous studies on the diet of this species. 相似文献
876.
Matthew D. Turner 《Geoforum》2009,40(5):746-81
In dryland areas of the Africa, livestock play important economic roles as commodities, wealth stores, producers of products, and agents of environmental change. Conventional depictions of livestock economies in this region have focused (in support or against) on the need for greater engagement of livestock producers with markets supplying meat to urban areas. This paper argues this singular focus has led analysts to ignore two important aspects of livestock economies: livestock as a preferred store of wealth across a wide range of social groups and the need for specialized labor to manage these livestock across open pastures to maintain their productivity and limit their negative environmental impacts. In the West African Sahel, the capital-like nature of livestock wealth has become more clear with a growing fraction of the region’s livestock owned by investors with little connection to livestock husbandry. Livestock investments are maintained on a day-to-day basis by hired herders who facilitate access to ephemeral pastures and water. A particular concern is the changing geographies of livestock ownership and the herding labor in relationship to regional pastures (to economic and environmental ends). This relationship will be explored using the case study of the Maasina region of central Mali - a historically important livestock region, which is now undergoing significant labor emigration. Building from a long-term ethnographic engagement with local livestock owners and herders, the results of ownership surveys of livestock herds across a 14-year period and interviews of urban-based emigrants from the study area about investment decisions will be used to analyze the changing geographies of livestock investment and herding labor in the Maasina. 相似文献
877.
We analyse the differences in the properties of the El Niño Southern Oscillation (ENSO) in a set of 17 coupled integrations with the flux-adjusted, 19-level HadCM3 model with perturbed atmospheric parameters. Within this ensemble, the standard deviation of the NINO3.4 deseasonalised SSTs ranges from 0.6 to 1.3 K. The systematic changes in the properties of the ENSO with increasing amplitude confirm that ENSO in HadCM3 is prevalently a surface (or SST) mode. The tropical-Pacific SST variability in the ensemble of coupled integrations correlates positively with the SST variability in the corresponding ensemble of atmosphere models coupled with a static mixed-layer ocean (“slab” models) perturbed with the same changes in atmospheric parameters. Comparison with the respective coupled ENSO-neutral climatologies and with the slab-model climatologies indicates low-cloud cover to be an important controlling factor of the strength of the ENSO within the ensemble. Our analysis suggests that, in the HadCM3 model, increased SST variability localised in the south-east tropical Pacific, not originating from ENSO and associated with increased amounts of tropical stratocumulus cloud, causes increased ENSO variability via an atmospheric bridge mechanism. The relationship with cloud cover also results in a negative correlation between the ENSO activity and the model’s climate sensitivity to doubling CO2. 相似文献
878.
Josephine Brown Matthew Collins Alexander W. Tudhope Thomas Toniazzo 《Climate Dynamics》2008,30(1):19-36
Palaeoclimate simulations provide an opportunity for climate model evaluation as well as having a potential role in assigning relative likelihood to different ensemble members in probabilistic climate change prediction, supplementing constraints provided by the instrumental record. Here we take some initial steps towards such an approach by performing ensemble experiments with the Hadley Centre HadCM3 model under pre-industrial and mid-Holocene (6,000 years before present) forcing conditions. We examine the changes in both mean tropical climate and El Niño-Southern Oscillation (ENSO) variability, as palaeoclimate records suggest that ENSO amplitude was reduced in the mid-Holocene. Experiments are performed with perturbations to physical parameters in the atmosphere–surface component of the model, and with different implementations of heat and freshwater flux adjustments. Heat flux adjustments are required to stabilise model versions in which perturbations cause a net radiative imbalance. While we find broad agreement between different model versions in terms of changes in mean climate in the mid-Holocene, a detailed and quantitative comparison with the geographically-sparse palaeo-record is limited by systematic model biases. In the simulations without seasonally-varying flux adjustments there are modest reductions in ENSO amplitude of the order of 10–15%, lower than the range of reductions inferred from coral proxy records. We examine the mechanisms for these changes, and discuss the implications for the design of future ensemble experiments to formally quantify uncertainty in climate change predictions using palaeoclimate simulations. 相似文献
879.
David A. Wake Ravi K. Sheth Robert C. Nichol Carlton M. Baugh Joss Bland-Hawthorn Matthew Colless Warrick J. Couch Scott M. Croom Roberto De Propris Michael J. Drinkwater Alastair C. Edge Jon Loveday Tsz Yan Lam Kevin A. Pimbblet Isaac G. Roseboom Nicholas P. Ross Donald P. Schneider Tom Shanks Robert G. Sharp 《Monthly notices of the Royal Astronomical Society》2008,387(3):1045-1062
880.
Vivienne Wild Guinevere Kauffmann Simon White Donald York Matthew Lehnert Timothy Heckman Patrick B. Hall Pushpa Khare Britt Lundgren Donald P. Schneider Daniel Vanden Berk 《Monthly notices of the Royal Astronomical Society》2008,388(1):227-241
Using data from the Sloan Digital Sky Survey data release 3 (SDSS DR3), we investigate how narrow (<700 km s−1 ) C iv and Mg ii quasar absorption-line systems are distributed around quasars. The C iv absorbers lie in the redshift range 1.6 < z < 4 and the Mg ii absorbers in the range 0.4 < z < 2.2. By correlating absorbers with quasars on different but neighbouring lines of sight, we measure the clustering of absorbers around quasars on comoving scales between 4 and 30 Mpc. The observed comoving correlation lengths are r o ∼ 5 h −1 Mpc , similar to those observed for bright galaxies at these redshifts. Comparing correlations between absorbers and the quasars, in whose spectra they are identified, then implies: (i) that quasars destroy absorbers to comoving distances of ∼300 kpc (C iv ) and ∼800 kpc (Mg ii ) along their lines of sight; (ii) that ≳40 per cent of C iv absorbers within 3000 km s−1 of the quasi-stellar object are not a result of large-scale clustering but rather are directly associated with the quasar itself; (iii) that this intrinsic absorber population extends to outflow velocities of the order of 12 000 km s−1 ; (iv) that this outflow component is present in both radio-loud and radio-quiet quasars and (v) that a small high-velocity outflow component is also observed in the Mg ii population. We also find an indication that absorption systems within 3000 km s−1 are more abundant for radio-loud quasars than for radio-quiet quasars. This suggests either that radio-loud objects live in more massive haloes, or that their radio activity generates an additional low-velocity outflow, or both. 相似文献