The AVOID programme’s new simulations of the global benefits of stringent climate change mitigation

Quantitative simulations of the global-scale benefits of climate change mitigation are presented, using a harmonised, self-consistent approach based on a single set of climate change scenarios. The approach draws on a synthesis of output from both physically-based and economics-based models, and incorporates uncertainty analyses. Previous studies have projected global and regional climate change and its impacts over the 21st century but have generally focused on analysis of business-as-usual scenarios, with no explicit mitigation policy included. This study finds that both the economics-based and physically-based models indicate that early, stringent mitigation would avoid a large proportion of the impacts of climate change projected for the 2080s. However, it also shows that not all the impacts can now be avoided, so that adaptation would also therefore be needed to avoid some of the potential damage. Delay in mitigation substantially reduces the percentage of impacts that can be avoided, providing strong new quantitative evidence for the need for stringent and prompt global mitigation action on greenhouse gas emissions, combined with effective adaptation, if large, widespread climate change impacts are to be avoided. Energy technology models suggest that such stringent and prompt mitigation action is technologically feasible, although the estimated costs vary depending on the specific modelling approach and assumptions.     

The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

Comet 81P/Wild 2 samples returned by NASA's Stardust mission provide an unequalled opportunity to study the contents of, and hence conditions and processes operating on, comets. They can potentially validate contentious interpretations of cometary infrared spectra and in situ mass spectrometry data: specifically the identification of phyllosilicates and carbonates. However, Wild 2 dust was collected via impact into capture media at ~6 km s^?1, leading to uncertainty as to whether these minerals were captured intact, and, if subjected to alteration, whether they remain recognizable. We simulated Stardust Al foil capture conditions using a two‐stage light‐gas gun, and directly compared transmission electron microscope analyses of pre‐ and postimpact samples to investigate survivability of lizardite and cronstedtite (phyllosilicates) and calcite (carbonate). We find the phyllosilicates do not survive impact as intact crystalline materials but as moderately to highly vesiculated amorphous residues lining resultant impact craters, whose bulk cation to Si ratios remain close to that of the impacting grain. Closer inspection reveals variation in these elements on a submicron scale, where impact‐induced melting accompanied by reducing conditions (due to the production of oxygen scavenging molten Al from the target foils) has resulted in the production of native silicon and Fe‐ and Fe‐Si‐rich phases. In contrast, large areas of crystalline calcite are preserved within the calcite residue, with smaller regions of vesiculated, Al‐bearing calcic glass. Unambiguous identification of calcite impactors on Stardust Al foil is therefore possible, while phyllosilicate impactors may be inferred from vesiculated residues with appropriate bulk cation to Si ratios. Finally, we demonstrate that the characteristic textures and elemental distributions identifying phyllosilicates and carbonates by transmission electron microscopy can also be observed by state‐of‐the‐art scanning electron microscopy providing rapid, nondestructive initial mineral identifications in Stardust residues.     

Integrated Futures for Europe’s Mountain Regions: Reconciling Biodiversity Conservation and Human Livelihoods

Introduction Europe's mountains cover nearly half of the continent's area (Price et al. 2004) and land cover varies significantly (European Commission 2004). In most massifs, except for Sicily, southern Greece, and the British Isles, forest cover is dominant. In northern Europe, grassland is proportionately more important, and much of the mountains of the British Isles is covered by moorland. In central and southern Europe, arable land is of far greater importance than grassland, with Med…     

Characterization of surface storage and runoff patterns following peatland restoration,Quebec, Canada

Blocking drainage ditches and creating bunds to limit surface water losses are important for restoring abandoned peat‐extraction sites in North America. However, these runoff control techniques have not been well characterized, particularly during the snowmelt period. Therefore, patterns of runoff timing and magnitude were evaluated in a peatland (Bois‐des‐Bel, Quebec, Canada) undergoing restoration (restored site), in comparison with an unrestored section of the same peatland (unrestored site). Snowmelt dominated runoff, representing over 79% of the April to August runoff for both sites in 2001. Low (25–35 cm) bunds constructed on the restored site detained water for much of the melt period, but some water loss occurred where bunds were breached. Overland flow and surface ponding were prevalent at the restored site, but were not evident at the unrestored site. At the restored site, the presence of bunds and frozen, saturated (thus impermeable) ground contributed to differences in snowmelt runoff patterns relative to the unrestored site. In the post‐snowmelt period (May–August 2001 and 2002), restored site runoff was reduced to 25% of that lost at the unrestored site. Both hydrometric and chemical hydrograph separation analysis using electrical conductivity indicated that blocked ditches restricted water losses from much of the restored site during the summer months, when the bunds had little effect on runoff. However, discharge peaks were greater at the restored site relative to the unrestored site and generally occurred more quickly following rainfall, because of the wetter antecedent conditions. Copyright © 2006 John Wiley & Sons, Ltd.     

Smoothed Particle Magnetohydrodynamics: Some Shocking Results

There have been some issues in the past in attempts to simulate magnetic fields using the smoothed particle hydrodynamics (SPH) method. SPH is well suited to star formation problems because of its Lagrangian nature. We present new, stable and conservative methods for magnetohydrodynamics (MHD) in SPH and present numerical tests on both linear waves and shocks in one dimension to show that it gives robust and accurate results.     

Hillslope‐swamp interactions and flow pathways in a hypermaritime rainforest,British Columbia

The process of water delivery to a headwater stream in a hypermaritime rainforest was examined using a variety of physical techniques and tracing with dissolved organic carbon (DOC) and the stable isotopes of water. Headwater swamps, often the major discharge zones for water draining off steep forest slopes, strongly affect the physical and chemical character of streamflow in the region. The headwater swamp selected for detailed investigation was sustained by relatively constant groundwater input from the steep colluvial slopes that maintained the water table above the ground surface. During significant storm events the water table rose quickly and the swamp expanded to engulf marginal pools that developed rapidly on the adjacent ground surfaces. The corresponding release of surface water directly to the stream typically comprised up to 95% of total stream discharge. The proportion of groundwater seepage to the stream by matrix flow (<1%) and via macropore‐fed springs (up to 73%) increased during the recession period, but could not be sustained over the longer term. In more protracted drying periods, deep groundwater contributions to the stream were routed first to the headwater swamp. Dissolved organic carbon (DOC) in the stream, measured daily or more frequently during storm events, was found to be directly proportional to discharge, owing to the domination of DOC‐rich headwater‐swamp water sources. Although δ¹⁸O and δ²H composition of rainwater, groundwater and stream flow were found to be similar, deuterium excess (d ? δ²H ? 8δ¹⁸O) of water components was often found to be distinct, and suggested short water residence times of roughly 12 days for one event. Overall, observations of a typical headwater swamp reveal that the groundwater regime is dominated by rapid infiltration and short, emergent flow paths. With a relatively short turnover time, potential disturbances to the system by harvesting of upslope areas can be expected to occur rapidly. Forest managers can mitigate some of the harmful effects of logging operations by respecting the integrity of headwater wetland systems. The nature and magnitude of such perturbations will require further study. Copyright © 2003 John Wiley & Sons, Ltd.     

A Comparison of Aspatial and Spatial Measures of Segregation

The modifiable areal unit problem arises when the boundaries that define neighborhoods affect perceived levels of segregation. Scholars postulate that this problem is exacerbated when one uses a definition of neighborhoods that is based on administrative units; doing so leads to an aspatial measure of segregation, which may or may not adequately account for the spatial relationships among residential locations. In this article, we assess whether aspatial and spatial definitions of neighborhoods produce different perceived levels of income segregation. Using an original individual‐level dataset on income in San Mateo County, California, we define each individual's neighborhood in three ways – two aspatial and one spatial. On the basis of these definitions of neighborhoods, we then estimate residential income segregation using the local Moran's I statistic. We report two primary findings. First, the three measures generate different perceived levels of income segregation. Specifically, we observe less income segregation when using the aspatial measures as compared with the spatial one. Second, the inconsistencies between these measures are systematic in such a way as to lead to different inferences when used to predict individual voter turnout.