Stable water isotopes in HadCM3: isotopic signature of El Nino-Southern Oscillation and the tropical amount effect

Stable water isotopes have been added to the full hydrological cycle of the Hadley Centre Climate model (HadCM3) coupled atmosphere-ocean GCM. Simulations of delta O-18 in precipitation and at the ocean surface compare well with observations for the present-day climate. The model has been used to investigate the isotopic anomalies associated with ENSO; it is found that the anomalous delta O-18 in precipitation is correlated with the anomalous precipitation amount in accordance with the "amount effect.'' The El Nino delta O-18 anomaly at the ocean surface is largest in coastal regions because of the mixing of ocean water and the more depleted runoff from the land surface. Coral delta O-18 anomalies were estimated, using an established empirical relationship, and generally reflect ocean surface delta O-18 anomalies in coastal regions and sea surface temperatures away from the coast. The spatial relationship between tropical precipitation and delta O-18 was investigated for the El Nino anomaly simulated by HadCM3. Weighting the El Nino precipitation anomaly by the precipitation amount at each grid box gave a large increase in the spatial correlation between tropical precipitation and delta O-18. This improvement was most apparent over land points and between 10 and 20 degrees of latitude

Media Coverage and Perceived Policy Influence of Environmental Actors: Good Strategy or Pyrrhic Victory?

In this article we analyze how media coverage for environmental actors (individual environmental activists and environmental movement organizations) is associated with their perceived policy influence in Canadian climate change policy networks. We conceptualize media coverage as the total number of media mentions an actor received in Canada’s two main national newspapers—the Globe and Mail and National Post. We conceptualize perceived policy influence as the total number of times an actor was nominated by other actors in a policy network as being perceived to be influential in domestic climate change policy making in Canada. Literature from the field of social movements, agenda setting, and policy networks suggests that environmental actors who garner more media coverage should be perceived as more influential in policy networks than actors who garner less coverage. We assess support for this main hypothesis in two ways. First, we analyze how actor attributes (such as the type of actor) are associated with the amount of media coverage an actor receives. Second, we evaluate whether being an environmental actor shapes the association between media coverage and perceived policy influence. We find a negative association between media coverage and perceived policy influence for individual activists, but not for environmental movement organizations. This case raises fundamental theoretical questions about the nature of relations between media and policy spheres, and the efficacy of media for signaling and mobilizing policy influence

Geographical Differences in the Forefoot Morphology – A Comparative Radiological Study of Feet in Malawi and UK

Background: Many skeletal morphological differences between populations have been reported with possible but unproven clinical importance. This study was aimed at identifying the normal radiographic findings and measurements seen in patients from Southern Africa and compares them to a European population’s values.Methods: AP foot radiographs of 40 adults from Blantyre, Malawi were compared with those of 40 adults from London, UK. For each patient, measurements were taken of: 1st and 2nd metatarsal lengths, the 1st/2nd intermetatarsal angle, the 1st metatarso- phalangeal angle (the ‘bunion’ angle), and the 2nd metatarsal mortice joint medial and lateral depths.Results: Our results show an increased 1st/2nd metatarsal angle in Malawian feet, but a reduced ‘bunion’ angle. We also found the second metatarsal length to be longer relative to the first in the Malawian foot, and the 2nd metatarsal base to be significantly more covered by its mortice than in UK feet.Conclusion: This racial anatomical variation may convey more stability and less risk of a Lisfranc dislocation. It is also important to be aware of the normal range of these values when considering the need for forefoot arthroplasty procedures

Theory of commensurable magnetic structures in holmium

The tendency for the period of the helically ordered moments in holmium to lock into values which are commensurable with the lattice is studied theoretically as a function of temperature and magnetic field. The commensurable effects are derived in the mean-field approximation from numerical calculations of the free energy of various commensurable structures, and the results are compared with the extensive experimental evidence collected during the last ten years on the magnetic structures in holmium. In general the stability of the different commensurable structures is found to be in accord with the experiments, except for the tau=5/18 structure observed a few degrees below T_N in a b-axis field. The trigonal coupling recently detected in holmium is found to be the interaction required to explain the increased stability of the tau=1/5 structure around 42 K, and of the tau=1/4 structure around 96 K, when a field is applied along the c-axis.Comment: REVTEX, 31 pages, 7 postscript figure

Sea ice feedbacks influence the isotopic signature of Greenland ice sheet elevation changes: Last interglacial HadCM3 simulations

Changes in the Greenland ice sheet (GIS) affect global sea level. Greenland stable water isotope (δ18O) records from ice cores offer information on past changes in the surface of the GIS. Here, we use the isotope-enabled Hadley Centre Coupled Model version 3 (HadCM3) climate model to simulate a set of last interglacial (LIG) idealised GIS surface elevation change scenarios focusing on GIS ice core sites. We investigate how δ18O depends on the magnitude and sign of GIS elevation change and evaluate how the response is altered by sea ice changes. We find that modifying GIS elevation induces changes in Northern Hemisphere atmospheric circulation, sea ice and precipitation patterns. These climate feedbacks lead to ice-core-averaged isotopic lapse rates of 0.49 ‰ (100 m)−1 for the lowered GIS states and 0.29 ‰ (100 m)−1 for the enlarged GIS states. This is lower than the spatially derived Greenland lapse rates of 0.62–0.72 ‰ (100 m)−1. These results thus suggest non-linearities in the isotope–elevation relationship and have consequences for the interpretation of past elevation and climate changes across Greenland. In particular, our results suggest that winter sea ice changes may significantly influence isotope–elevation gradients: winter sea ice effect can decrease (increase) modelled core-averaged isotopic lapse rate values by about −19 % (and +28 %) for the lowered (enlarged) GIS states, respectively. The largest influence of sea ice on δ18O changes is found in coastal regions like the Camp Century site

Indian monsoon variability in response to orbital forcing during the late Pliocene

The Asian monsoon is a major component of the global climate system and can be divided into two subsystems, the Indian monsoon and the East Asian monsoon. Insights into monsoon behaviour and dynamics can be gained through studying past warm intervals in Earth's history. One such interval is the Pliocene epoch, specifically the mid-Piacenzian Warm Period (mPWP; 3.264–3.025 Ma). This time is characterised as a period of sustained warmth, with annual mean temperatures 2–3 °C higher than the pre-industrial era. Studies have examined the East Asian monsoon during the mPWP from both a geological data and climate modelling perspective. However, there has been little investigation into the behaviour of the Indian monsoon. Using a coupled atmosphere-ocean global climate model (HadCM3), the Indian summer monsoon response to orbital forcing during the mPWP is studied. Of the simulated interglacial events (Marine Isotope Stages KM5c, KM3, K1 and G17), MIS KM5c is the only one with a near-modern orbital forcing. This experiment is compared to a pre-industrial simulation to determine the nature of the mPWP Indian summer monsoon in the absence of a different pattern if insolation forcing. The monsoon at MIS KM5c, is simulated to be stronger than pre-industrial, with higher surface air temperatures and precipitation over land due to higher levels of CO2. MIS G17, K1, and KM3 represent interglacial events of similar magnitude with different insolation forcing than MIS KM5c. The Indian summer monsoon is simulated to be significantly stronger for the interglacials K1 and KM3, compared to KM5c. This is due to stronger precession forcing causing an increase in summer surface air temperature and precipitation. When combined with Pliocene geological boundary conditions, these results highlight the significant effect of orbital forcing on the strength of the Indian summer monsoon. The sensitivity of the Indian monsoon to orbital forcing has important implications for any parallels drawn between Pliocene and future monsoon behaviour

Analysis of 1,000+ Type-Strain Genomes Substantially Improves Taxonomic Classification of Alphaproteobacteria.

The class Alphaproteobacteria is comprised of a diverse assemblage of Gram-negative bacteria that includes organisms of varying morphologies, physiologies and habitat preferences many of which are of clinical and ecological importance. Alphaproteobacteria classification has proved to be difficult, not least when taxonomic decisions rested heavily on a limited number of phenotypic features and interpretation of poorly resolved 16S rRNA gene trees. Despite progress in recent years regarding the classification of bacteria assigned to the class, there remains a need to further clarify taxonomic relationships. Here, draft genome sequences of a collection of genomes of more than 1000 Alphaproteobacteria and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa recognized as problematic long ago but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera and of a variety of genera to other families. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which are confirmed as valuable taxonomic markers. Similarly, analysis of the gene content was shown to provide valuable taxonomic insights in the class. Significant incongruities between 16S rRNA gene and whole genome trees were not found in the class. The incongruities that became obvious when comparing the results of the present study with existing classifications appeared to be caused mainly by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. Another probable cause of misclassifications in the past is the partially low overall fit of phenotypic characters to the sequence-based tree. Even though a significant degree of phylogenetic conservation was detected in all characters investigated, the overall fit to the tree varied considerably

Fertilizer Impact on Groundwater in Utah

Water quality has become the focal point of many decisions involving crop production. Crop production depends on specific inputs including fertilizer application. Without proper fertilization a farmer cannot achieve maximum economic returns. Crop yields in Utah have been increased over 50% by nitrogen fertilizer application alone. However, increasing nitrogen application beyond that needed for optimum economic return does more harm than good. This is especially true when groundwater concerns are ressed

Agricultural pesticide hazard to groundwater in Utah

We gratefully acknowledge the funding support of the Utah Department of Agriculture and the following offices at Utah State University. The Department of Agricultural and Irrigation Engineering, the International Irrigation Center, the Department of Animal, Dairy and Veterinary Sciences, the Department of Soil Science and Biometerology, and the University Extension Services

Ocean circulation drifts in multi-millennial climate simulations: the role of salinity corrections and climate feedbacks

Low-resolution, complex general circulation models (GCMs) are valuable tools for studying the Earth system on multi-millennial timescales. However, slowly evolving salinity drifts can cause large shifts in climatic and oceanic regimes over thousands of years. We test two different schemes for neutralising unforced salinity drifts in the FAMOUS GCM: surface flux correction and volumetric flux correction. Although both methods successfully maintain a steady global mean salinity, local drifts and subsequent feedbacks promote cooling (≈ 4 °C over 6000 years) and freshening (≈ 2 psu over 6000 years) in the North Atlantic Ocean, and gradual warming (≈ 0.2 °C per millennium) and salinification (≈ 0.15 psu per millennium) in the North Pacific Ocean. Changes in the surface density in these regions affect the meridional overturning circulation (MOC), such that, after several millennia, the Atlantic MOC (AMOC) is in a collapsed state, and there is a strong, deep Pacific MOC (PMOC). Furthermore, the AMOC exhibits a period of metastability, which is only identifiable with run lengths in excess of 1500 years. We also compare simulations with two different land surface schemes, demonstrating that small biases in the surface climate may cause regional salinity drifts and significant shifts in the MOC (weakening of the AMOC and the initiation then invigoration of PMOC), even when the global hydrological cycle has been forcibly closed. Although there is no specific precursor to the simulated AMOC collapse, the northwest North Pacific and northeast North Atlantic are important areas that should be closely monitored for trends arising from such biases