An assessment of the climate change impacts on groundwater recharge at a continental scale using a probabilistic approach with an ensemble of GCMs   总被引：1，自引：0，他引：1  

Russell S. Crosbie  Trevor Pickett  Freddie S. Mpelasoka  Geoff Hodgson  Stephen P. Charles  Olga V. Barron 《Climatic change》2013,117(1-2):41-53

This study used 16 Global Climate Models and three global warming scenarios to make projections of recharge under a 2050 climate for the entire Australian continent at a 0.05° grid resolution. The results from these 48 future climate variants have been fitted to a probability distribution to enable the results to be summarised and uncertainty quantified. The median results project a reduction in recharge across the west, centre and south of Australia and an increase in recharge across the north and a small area in the east of the continent. The range of results is quite large and for large parts of the continent encompasses both increases and decreases in recharge. This makes it difficult to utilise for water resources management so the results have been analysed with a risk analysis framework; this enables the future projections for groundwater recharge to be communicated to water managers in terms of likelihood and consequence of a reduction in recharge. This highlights an important message for water resource managers that in most areas of Australia they will be making decisions on water allocations under considerable uncertainty as to the direction and magnitude of recharge change under a future climate and that this uncertainty may be irreducible.  相似文献   

Critical issues for the calculation of the social cost of CO2: why the estimates from PAGE09 are higher than those from PAGE2002     

Chris Hope 《Climatic change》2013,117(3):531-543

PAGE09 is an updated version of the PAGE2002 integrated assessment model (Hope 2011a). The default PAGE09 model gives a mean estimate of the social cost of CO₂ (SCCO₂) of $106 per tonne of CO₂, compared to $81 from the PAGE2002 model used in the Stern review (Stern 2007). The increase is the net result of several improvements that have been incorporated into the PAGE09 model in response to the critical debate around the Stern review: the adoption of the A1B socio-economic scenario, rather than A2 whose population assumptions are now thought to be implausible; the use of ranges for the two components of the discount rate, rather than the single values used in the Stern review; a distribution for the climate sensitivity that is consistent with the latest estimates from IPCC 2007a; less adaptation than in PAGE2002, particularly in the economic sector, which was criticised for possibly being over-optimistic; and a more theoretically-justified basis of valuation that gives results appropriate to a representative agent from the focus region, the EU. The effect of each of these adjustments is quantified and explained.  相似文献   

The use of the land-sea warming contrast under climate change to improve impact metrics     

Manoj M. Joshi  Andrew G. Turner  Chris Hope 《Climatic change》2013,117(4):951-960

A favoured method of assimilating information from state-of-the-art climate models into integrated assessment models of climate impacts is to use the transient climate response (TCR) of the climate models as an input, sometimes accompanied by a pattern matching approach to provide spatial information. More recent approaches to the problem use TCR with another independent piece of climate model output: the land-sea surface warming ratio (φ). In this paper we show why the use of φ in addition to TCR has such utility. Multiple linear regressions of surface temperature change onto TCR and φ in 22 climate models from the CMIP3 multi-model database show that the inclusion of φ explains a much greater fraction of the inter-model variance than using TCR alone. The improvement is particularly pronounced in North America and Eurasia in the boreal summer season, and in the Amazon all year round. The use of φ as the second metric is beneficial for three reasons: firstly it is uncorrelated with TCR in state-of-the-art climate models and can therefore be considered as an independent metric; secondly, because of its projected time-invariance, the magnitude of φ is better constrained than TCR in the immediate future; thirdly, the use of two variables is much simpler than approaches such as pattern scaling from climate models. Finally we show how using the latest estimates of φ from climate models with a mean value of 1.6—as opposed to previously reported values of 1.4—can significantly increase the mean time-integrated discounted damage projections in a state-of-the-art integrated assessment model by about 15 %. When compared to damages calculated without the inclusion of the land-sea warming ratio, this figure rises to 65 %, equivalent to almost 200 trillion dollars over 200 years.  相似文献   

THE VEGETATIONAL CHANGES OF THE LAST 20,000 YEARS AT TELEFOMIN, PAPUA NEW GUINEA     

Geoff Hope  MSc.  Ph.D. 《Singapore journal of tropical geography》1983,4(1):25-33

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Evidence for a 200 km thick diamond-bearing root beneath the Central Mackenzie Valley,Northwest Territories,Canada? Diamond indicator mineral geochemistry from the Horn Plateau and Trout Lake regions     

Poitras  St&#;phane P.  Pearson  D. Graham  Hardman  Matthew F.  Stachel  Thomas  Nowell  Geoff M.  Cairns  Scott 《Mineralogy and Petrology》2018,112(2):719-736

The Central Mackenzie Valley (CMV) area of Northwest Territories is underlain by Precambrian basement belonging to the North American Craton. The potential of this area to host kimberlitic diamond deposits is relatively high judging from the seismologically-defined lithospheric thickness, age of basement rocks (2.2–1.7 Ga) and presence of kimberlite indicator minerals (KIMs) in Quaternary sediments. This study presents data for a large collection of KIMs recovered from stream sediments and till samples from two study areas in the CMV, the Horn Plateau and Trout Lake. In the processed samples, peridotitic garnets dominate the KIM grain count for both regions (> 25% each) while eclogitic garnet is almost absent in both regions (< 1% each). KIM chemistry for the Horn Plateau indicates significant diamond potential, with a strong similarity to KIM systematics from the Central and Western Slave Craton. The most significant issue to resolve in assessing the local diamond potential is the degree to which KIM chemistry reflects local and/or distal kimberlite bodies. Radiogenic isotope analysis of detrital kimberlite-related CMV ilmenite and rutile grains requires at least two broad age groups for eroded source kimberlites. Statistical analysis of the data suggests that it is probable that some of these KIMs were derived from primary and/or secondary sources within the CMV area, while others may have been transported to the area from the east-northeast by Pleistocene glacial and/or glaciofluvial systems. At this stage, KIM chemistry does not allow the exact location of the kimberlitic source(s) to be constrained.

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Staging the Local: rethinking scale in farmers' markets     

Bethaney Turner  Cathy Hope 《The Australian geographer》2015,46(2):147-163

Local food has become a significant focus of food studies analysis in recent years with much of this work identifying the potential environmental, social and economic benefits of food localisation. However, a growing body of literature destabilises these assumed benefits with research now questioning the utility of scale in assessing food system outcomes. This paper explores this destabilisation by examining how concepts associated with the ‘local’ have been deployed by the Capital Region Farmers Market (CRFM) in the Australian Capital Territory (ACT). This leads to two key conclusions: firstly, the practical case study confirms theoretical insights highlighting the instability of the local, identifying how it is animated in multiple and sometimes contradictory ways often in response to conventional market forces; and secondly, we argue that the role of farmers' markets may not be best understood through the lens of the local but, rather, through their role in facilitating citizen engagement with the food system via the direct consumer–producer relationship at markets and the characteristics of the food purchased there (i.e. freshness and quality). In these ways, farmers' markets can disrupt conventional forms of engagement with the food system, creating a space that enhances social embeddedness and which may promote new forms of consumer understanding of food systems.  相似文献   

Flow network derivation from a high resolution DEM in a low relief,agrarian landscape   总被引：1，自引：0，他引：1  

Wolfgang Schwanghart  Geoff Groom  Nikolaus J. Kuhn  Goswin Heckrath 《地球表面变化过程与地形》2013,38(13):1576-1586

Digital flow networks derived from digital elevation models (DEMs) sensitively react to errors due to measurement, data processing and data representation. Since high‐resolution DEMs are increasingly used in geomorphological and hydrological research, automated and semi‐automated procedures to reduce the impact of such errors on flow networks are required. One such technique is stream‐carving, a hydrological conditioning technique to ensure drainage connectivity in DEMs towards the DEM edges. Here we test and modify a state‐of‐the‐art carving algorithm for flow network derivation in a low‐relief, agricultural landscape characterized by a large number of spurious, topographic depressions. Our results show that the investigated algorithm reconstructs a benchmark network insufficiently in terms of carving energy, distance and a topological network measure. The modification to the algorithm that performed best, combines the least‐cost auxiliary topography (LCAT) carving with a constrained breaching algorithm that explicitly takes automatically identified channel locations into account. We applied our methods to a low relief landscape, but the results can be transferred to flow network derivation of DEMs in moderate to mountainous relief in situations where the valley bottom is broad and flat and precise derivations of the flow networks are needed. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Policy uncertainty and diffusion of carbon capture and storage in an optimal region     

Chris W. Hope 《Climate Policy》2013,13(5):565-572

Abstract

The social cost of carbon (SCC) is the value of the climate change impacts from 1 tonne of carbon emitted today as CO₂, aggregated over time and discounted back to the present day. We used PAGE2002, the same probabilistic integrated assessment model as used by the Stern Review (Stern et al., 2006), to calculate the SCC and to examine how it varies with discount rate; and find that it is not sensitive to the path of emissions on which the tonne of carbon is superimposed. The mean value of the SCC is $43 per tonne under both a business-as-usual scenario, and under a scenario aimed at stabilizing CO₂ concentrations at 550 ppm. This counter-intuitive result is caused by the interplay between the logarithmic relationship between forcing and concentration, the nonlinear relationship of damage to temperature, and discounting. However, the SCC is sensitive to a number of scientific and economic inputs to the model. Two recent distributions for the sensitivity of climate to a doubling of atmospheric CO₂ (Murphy et al., 2004; Stainforth et al., 2005) increase the mean value of the SCC from $43 to $68 and $90 per tonne. Using a pure rate of time preference of 0.1% per year, as in the Stern Review, gives a mean SCC of $365 per tonne.  相似文献   

The origin of crystalline residues in Stardust Al foils: Surviving cometary dust or crystallized impact melts?     

Penelope J. WOZNIAKIEWICZ  Anton T. KEARSLEY  Hope A. ISHII  Mark J. BURCHELL  John P. BRADLEY  Nick TESLICH  Mike J. COLE  Mark C. PRICE 《Meteoritics & planetary science》2012,47(4):660-670

Abstract– Samples returned by the Stardust mission from comet 81P/Wild 2 provide an unequaled opportunity to investigate cometary formation and evolution. Crystalline silicates have been identified in impact craters in Stardust Al foil, yet their origin is ambiguous. They may be original cometary components, or they may have grown from melt generated by impact. We have now studied experimental impacts of the calcium silicate mineral wollastonite, using scanning and transmission electron microscopy to document the relationship between impact feature shape and crystal lattice orientation in impact residue. Wollastonite can have a characteristic acicular habit, forming crater shapes that indicate crystal orientation upon impact. From extracted impact residue, we determined the lattice orientation of crystalline material for comparison with the whole particle orientation. We assume that crystallization from melt, without surviving seed nuclei, should result in randomly oriented crystallite growth, with no preferred direction for individual crystals. However, we find that the majority of crystalline material in the residue retains b‐axis orientation parallel to the long axis of the crater form. This, together with impact parameter calculations and lack of Al incorporation by the residue (suggesting melting did not occur), indicates that these crystals and, by analogy, the majority of Al‐free crystalline silicates in Stardust foil, are surviving remnants of the impactor. Furthermore, amorphous wollastonite residue probably did not form via melting and subsequent quenching, but instead by high‐pressure amorphization or degradation of unquenchable phases. Finally, one crystal studied appears to be a new high‐pressure/temperature polymorph of CaSiO₃, indicating that such polymorphs may be observed in Stardust residues in craters.  相似文献   

Numerical description of coalbed methane desorption stages based on isothermal adsorption experiment   总被引：1，自引：0，他引：1  

ZHANG Zheng  QIN Yong  Geoff X WANG  FU XueHai 《中国科学:地球科学(英文版)》2013,(6):1029-1036

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