Resilience to change in two coastal communities: Using the maximum dexterity fleet

Using whole-ecosystem dynamic simulation models fitted to local data, two coastal communities are described (temperate, northern British Columbia, Canada; tropical, Raja Ampat, Indonesia) where relatively poor fishers’ livelihoods are threatened by climate change and overfishing. A novel theoretical minimum bycatch scenario, the ‘maximum dexterity fleet’, is combined with a search algorithm specifying optimal fisheries to achieve economic and biodiversity goals. Potential gains made by approaching an optimal fleet configuration prove robust against increased risks from climate variability. Although fish, gear and way of life differ greatly, in both communities it is suggested that dexterity (adroitness in adapting fishing gear) could lead to improved benefits from fishing.     

The Ballybofey Anticline: A solution of the general structure of parts of Donegal and Tyrone

A tight early fold, the Ballybofey anticline, trends south-eastwards across central Donegal. South-west of its axial trace the Dalradian strata are inverted so that the rocks high in the Series occur at the lowest structural level, next to, and facing downwards, the supposedly Moinian psammites in the core of the Lough Derg antiform. Rapid facies changes occur in the Dalradian rocks across the Caledonian strike.     

Fluvial morphometry of supraglacial river networks on the southwest Greenland Ice Sheet

Extensive, complex supraglacial river networks form on the southwest Greenland ice sheet (GrIS) surface each melt season. These networks are the dominant pathways for surface meltwater transport on this part of the ice sheet, but their fluvial morphometry has received little study. This paper utilizes high-resolution (2 m) WorldView-1/2 images, digital elevation models, and GIS tools to present a detailed morphometric characterization (river number, river length, Strahler stream order, width, depth, bifurcation ratio, braiding index, drainage density, slope, and relief ratio) for 523 GrIS supraglacial river networks. A new algorithm is presented to determine Strahler stream order in supraglacial environments. Results show that (1) Supraglacial river networks are broadly similar to terrestrial landscapes in that they follow Horton’s laws (river number, mean river length, and slope versus stream order), widen downstream, and have comparable mean bifurcation ratios (3.7 ± 1.9) and braiding indices; (2) unlike terrestrial systems, supraglacial drainage densities (0.90–4.75 km/km²) have no correlation with elevation relief, but instead display a weakly inverse correlation with ice surface elevation; (3) both well-developed (e.g., fifth-order) and discrete (e.g., first-order) supraglacial river networks form on the ice sheet, with the latter associated with short flow distances upstream of a terminal moulin; (4) mean river flow widths increase substantially, but flow depths only modestly, with increasing stream order. Viewed collectively, the 523 supraglacial river networks studied here display fluvial morphometries both similar and dissimilar to terrestrial systems, with moulin capture an important physical process driving the latter.     

Uncertainties in climate stabilization

The atmospheric composition, temperature and sea level implications out to 2300 of new reference and cost-optimized stabilization emissions scenarios produced using three different Integrated Assessment (IA) models are described and assessed. Stabilization is defined in terms of radiative forcing targets for the sum of gases potentially controlled under the Kyoto Protocol. For the most stringent stabilization case (“Level 1” with CO₂ concentration stabilizing at about 450 ppm), peak CO₂ emissions occur close to today, implying (in the absence of a substantial CO₂ concentration overshoot) a need for immediate CO₂ emissions abatement if we wish to stabilize at this level. In the extended reference case, CO₂ stabilizes at about 1,000 ppm in 2200—but even to achieve this target requires large and rapid CO₂ emissions reductions over the twenty-second century. Future temperature changes for the Level 1 stabilization case differ noticeably between the IA models even when a common set of climate model parameters is used (largely a result of different assumptions for non-Kyoto gases). For the Level 1 stabilization case, there is a probability of approximately 50% that warming from pre-industrial times will be less than (or more than) 2°C. For one of the IA models, warming in the Level 1 case is actually greater out to 2040 than in the reference case due to the effect of decreasing SO₂ emissions that occur as a side effect of the policy-driven reduction in CO₂ emissions. This effect is less noticeable for the other stabilization cases, but still leads to policies having virtually no effect on global-mean temperatures out to around 2060. Sea level rise uncertainties are very large. For example, for the Level 1 stabilization case, increases range from 8 to 120 cm for changes over 2000 to 2300.     

Sampling of Mars analogue materials in a laboratory environment

Acta Geotechnica - Two laboratory test series were performed with the aim of ensuring the proper functionality of the key sampling mechanisms installed aboard the Mars rover ExoMars, currently...