On the use of IPCC-class models to assess the impact of climate on Living Marine Resources

The study of climate impacts on Living Marine Resources (LMRs) has increased rapidly in recent years with the availability of climate model simulations contributed to the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Collaboration between climate and LMR scientists and shared understanding of critical challenges for such applications are essential for developing robust projections of climate impacts on LMRs. This paper assesses present approaches for generating projections of climate impacts on LMRs using IPCC-class climate models, recommends practices that should be followed for these applications, and identifies priority developments that could improve current projections. Understanding of the climate system and its representation within climate models has progressed to a point where many climate model outputs can now be used effectively to make LMR projections. However, uncertainty in climate model projections (particularly biases and inter-model spread at regional to local scales), coarse climate model resolution, and the uncertainty and potential complexity of the mechanisms underlying the response of LMRs to climate limit the robustness and precision of LMR projections. A variety of techniques including the analysis of multi-model ensembles, bias corrections, and statistical and dynamical downscaling can ameliorate some limitations, though the assumptions underlying these approaches and the sensitivity of results to their application must be assessed for each application. Developments in LMR science that could improve current projections of climate impacts on LMRs include improved understanding of the multi-scale mechanisms that link climate and LMRs and better representations of these mechanisms within more holistic LMR models. These developments require a strong baseline of field and laboratory observations including long time series and measurements over the broad range of spatial and temporal scales over which LMRs and climate interact. Priority developments for IPCC-class climate models include improved model accuracy (particularly at regional and local scales), inter-annual to decadal-scale predictions, and the continued development of earth system models capable of simulating the evolution of both the physical climate system and biosphere. Efforts to address these issues should occur in parallel and be informed by the continued application of existing climate and LMR models.     

Tectonic implications of some field relations of the Adelaidean Cooee Dolerite,Tasmania

Complex contact relations between thin sills of the Adelaidean Cooee Dolerite and the enclosing flysch sediments (Burnie Formation) indicate emplacement of the sills into substantially uncompacted quasi‐liquid sediments very shortly after deposition. The sills are consequently coeval with the sediments rather than synchronous with the first phase of folding of the sediments (the Penguin Orogeny).

The K/Ar date on the Cooee Dolerite, here revised as 725 ± 35 m.y. (J. Richards, pers. comm.), very probably provides an estimate of the age of the sediments, rather than the age of the orogeny. Age relationships of the Cooee Dolerite, its host sediments and their deformation proposed hitherto can no longer be regarded as settled. The Burnie Formation may be part of a passive continental margin to the Rocky Cape Block, which was deformed during the Cambrian as a result of subduction beneath the active margin of the Tyennan Block.     

Fore‐arc evolution in the Tasman Geosyncline: The origin of the southeast Australian continental crust

A new general model describing the extended evolution of fore‐arc terrains is used to analyse the evolution of the southern Tasman Geosyncline and the concomitant growth and kratonisation of the continental crust of southeast Australia during the Palaeozoic. The southern Tasman Geosyncline comprises ten arc terrains (here defined), most of which are east‐facing, and several features formed by crustal extension. Each arc terrain consists of several strato‐tectonic units: a volcanic arc, subduction complex and fore‐arc sequence formed during subduction; and an overlying post‐arc sequence which post‐dates subduction and is composed of flysch, neritic sediments or subaerial volcanics.

When these materials attained a thickness of c. 20 km their internal heat‐balance caused partial melting of the subduction complex and the hydrated oceanic lithosphere trapped beneath it, to yield S‐ and I‐type granitic magma. The magma rose, inducing pervasive deformation of each arc terrain and emplacement of granitoid plutons at high levels in the evolving crust. Transitional basins then developed in many terrains on top of their volcanic arcs or the thinner parts of the buried accretionary prisms. After deformation of the transitional sequences, platform cover accumulated, marking the completion of kratonisation.

Analysis of each arc terrain in terms of the above units leads to a predicted ‘stratigraphy’ for the continental crust of southeast Australia. The crust is complexly layered, with lateral discontinuities reflecting the boundaries of arc terrains which were successively accreted, principally back‐arc to fore‐arc, during crustal development.     

Permeameter data verify new turbulence process for MODFLOW

A sample of Key Largo Limestone from southern Florida exhibited turbulent flow behavior along three orthogonal axes as reported in recently published permeameter experiments. The limestone sample was a cube measuring 0.2 m on edge. The published nonlinear relation between hydraulic gradient and discharge was simulated using the turbulent flow approximation applied in the Conduit Flow Process (CFP) for MODFLOW-2005 mode 2, CFPM2. The good agreement between the experimental data and the simulated results verifies the utility of the approach used to simulate the effects of turbulent flow on head distributions and flux in the CFPM2 module of MODFLOW-2005.     

Sensitivity of climate response to variations in freshwater hosing location

In a recent intercomparison of the response of general circulation models (GCMs) to high-latitude freshwater forcing (Stouffer et al., J Climate 19(8):1365–1387, 2006), a number of the GCMs investigated showed a localised warming response in the high-latitude North Atlantic, as opposed to the cooling that the other models showed. We investigated the causes for this warming by testing the sensitivity of the meridional overturning circulation (MOC) to variations in freshwater forcing location, and then analysing in detail the causes of the warming. By analysing results from experiments with HadCM3, we are able to show that the high-latitude warming is independent of the exact location of the additional freshwater in the North Atlantic or Arctic Ocean basin. Instead, the addition of freshwater changes the circulation in the sub-polar gyre, which leads to enhanced advection of warm, saline, sub-surface water into the Greenland–Iceland–Norwegian Sea despite the overall slowdown of the MOC. This sub-surface water is brought to the surface by convection, where it leads to a strong warming of the surface waters and the overlying atmosphere.     

Legacies from three former manufactured-gas plants: impacts on groundwater quality

Groundwater contamination due to accidental releases of mono- and polycyclic aromatic compounds (MAHs and PAHs) from decommissioned manufactured-gas plants is an ongoing and litigious problem. The MAHs and PAHs are derived from coal tar, which was a by-product of the gas-manufacturing process. While originally designed to contain coal tar, the manufactured-gas plant structures that remain today have often degraded over time and are not completely leak-proof. Over a period of many years, subsurface water has seeped into and out of the structures, resulting in groundwater contamination. This was particularly true once the tops of the structures were removed. In this study, process-based simulations were conducted to estimate the groundwater-quality impacts of accidental releases of dissolved naphthalene (C₁₀H₈) from the sites of three former manufactured-gas plants. The results from one-dimensional, transient, unsaturated, near-surface fluid-flow and solute-transport simulations served as input to three-dimensional saturated subsurface fluid-flow and solute-transport simulations. The simulation results and sensitivity analysis reported here indicate that accidental releases of naphthalene had significant, negative impacts on groundwater quality at each of the three sites. Electronic Publication     

Variations of the neutralino elastic cross-section with CP-violating phases

We analyze the neutralino–nucleus elastic cross-section in the minimal supersymmetric extension of the standard model (MSSM), including contributions from CP-violating phases, using the four-fermi neutralino–quark interaction. Over a wide range of the MSSM parameter space, we show the variations in the cross-sections due to these phases. We further concentrate on the regions which are consistent with constraints from the electric dipole moment of the electron, neutron and mercury atom. In the regions we examine in detail, we find suppressions by up to a factor of two, while enhancements in the cross-sections are no greater than 10%.