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801.
Stabilizing greenhouse gas concentrations at low levels: an assessment of reduction strategies and costs 总被引:2,自引:8,他引:2
Detlef P. van Vuuren Michel G. J. den Elzen Paul L. Lucas Bas Eickhout Bart J. Strengers Bas van Ruijven Steven Wonink Roy van Houdt 《Climatic change》2007,81(2):119-159
On the basis of the IPCC B2, A1b and B1 baseline scenarios, mitigation scenarios were developed that stabilize greenhouse
gas concentrations at 650, 550 and 450 and – subject to specific assumptions – 400 ppm CO2-eq. The analysis takes into account a large number of reduction options, such as reductions of non-CO2 gases, carbon plantations and measures in the energy system. The study shows stabilization as low as 450 ppm CO2-eq. to be technically feasible, even given relatively high baseline scenarios. To achieve these lower concentration levels,
global emissions need to peak within the first two decades. The net present value of abatement costs for the B2 baseline scenario
(a medium scenario) increases from 0.2% of cumulative GDP to 1.1% as the shift is made from 650 to 450 ppm. On the other hand,
the probability of meeting a two-degree target increases from 0%–10% to 20%–70%. The mitigation scenarios lead to lower emissions
of regional air pollutants but also to increased land use. The uncertainty in the cost estimates is at least in the order
of 50%, with the most important uncertainties including land-use emissions, the potential for bio-energy and the contribution
of energy efficiency. Furthermore, creating the right socio-economic and political conditions for mitigation is more important
than any of the technical constraints. 相似文献
802.
Despite the broad impact and importance of saltwater intrusion in coastal aquifers, little research has been directed towards forecasting saltwater intrusion in areas where the source of saltwater is uncertain. Saline contamination in inland groundwater supplies is a concern for numerous communities in the southern US including the city of Deltona, Florida. Furthermore, conventional numerical tools for forecasting saltwater contamination are heavily dependent on reliable characterization of the physical characteristics of underlying aquifers, information that is often absent or challenging to obtain. To overcome these limitations, a reliable alternative data-driven model for forecasting salinity in a groundwater supply was developed for Deltona using the fast orthogonal search (FOS) method. FOS was applied on monthly water-demand data and corresponding chloride concentrations at water supply wells. Groundwater salinity measurements from Deltona water supply wells were applied to evaluate the forecasting capability and accuracy of the FOS model. Accurate and reliable groundwater salinity forecasting is necessary to support effective and sustainable coastal-water resource planning and management. The available (27) water supply wells for Deltona were randomly split into three test groups for the purposes of FOS model development and performance assessment. Based on four performance indices (RMSE, RSR, NSEC, and R), the FOS model proved to be a reliable and robust forecaster of groundwater salinity. FOS is relatively inexpensive to apply, is not based on rigorous physical characterization of the water supply aquifer, and yields reliable estimates of groundwater salinity in active water supply wells. 相似文献
803.
Tobias Diehl John Clinton Nicolas Deichmann Carlo Cauzzi Philipp Kästli Toni Kraft Irene Molinari Maren Böse Clotaire Michel Manuel Hobiger Florian Haslinger Donat Fäh Stefan Wiemer 《Swiss Journal of Geoscience》2018,111(1-2):221-244
This report summarizes the seismicity in Switzerland and surrounding regions in the years 2015 and 2016. In 2015, the Swiss Seismological Service detected and located 735 earthquakes in the region under consideration. With a total of 20 earthquakes of magnitude ML ≥ 2.5, the seismic activity of potentially felt events in 2015 was close to the average of 23 earthquakes over the previous 40 years. Seismic activity was above average in 2016 with 872 located earthquakes of which 31 events had ML ≥ 2.5. The strongest event in the analyzed period was the ML 4.1 Salgesch earthquake, which occurred northeast of Sierre (VS) in October 2016. The event was felt in large parts of Switzerland and had a maximum intensity of V. Derived focal mechanisms and relative hypocenter relocations of aftershocks image a SSE dipping reverse fault, which likely also hosted an ML 3.9 earthquake in 2003. Another remarkable earthquake sequence in the Valais occurred close to Sion with four felt events (ML 2.7–3.2) in 2015/16. We associate this sequence with a system of WNW-ESE striking fault segments north of the Rhône valley. Similarities with a sequence in 2011, which was located about 10 km to the NE, suggest the existence of an en-echelon system of basement faults accommodating dextral slip along the Rhône-Simplon line in this area. Another exceptional earthquake sequence occurred close to Singen (Germany) in November 2016. Relocated hypocenters and focal mechanisms image a SW dipping transtensional fault segment, which is likely associated with a branch of the Hegau-Bodensee Graben. On the western boundary of this graben, micro-earthquakes close to Schlattingen (TG) in 2015/16 are possibly related to a NE dipping branch of the Neuhausen Fault. Other cases of earthquakes felt by the public during 2015/16 include earthquakes in the region of Biel, Vallorcine, Solothurn, and Savognin. 相似文献
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807.
Gerges Firas Nassif Hani Geng Xiaolong Michael Holly A. Boufadel Michel C. 《Natural Hazards》2022,111(2):1271-1299
Natural Hazards - Community resilience refers to the degree to which a community can survive and recover following a disaster. While resilience itself is well understood, decisions that would... 相似文献
808.
Field observations by divers indicated that a high rate of predation of whelks (Buccinum undatum) by starfish (Asterias rubens) occurred in an area disturbed by scallop dredging, although these whelks mostly appeared to be alive and externally undamaged. The ability of whelks to escape from starfish was tested in the laboratory after they were dropped or rolled to simulate direct physical contact with bottom fishing gear. Dropping whelks did not significantly affect their escape behaviour, but whelks which had been rolled took significantly longer to right themselves and were significantly less likely to perform an escape response than whelks that had not experienced this treatment. This study suggests that demersal fishing may indirectly increase whelk mortality by increasing their risk of predation. 相似文献
809.
J. L. A. Fordham H. Kawakami R. M. Michel R. Much J. R. Robinson 《Monthly notices of the Royal Astronomical Society》2000,319(2):414-418
The micro‐channel plate intensified CCD photon counting detector developed at University College London has been upgraded to allow time-resolved spectroscopic optical data to be acquired on periodical sources such as pulsars. First observing trials have been carried out, acquiring spectroscopic data on the Crab pulsar. The detector was phase locked to the pulsar period and a temporal resolution of 41.4 μs employed. The phase locking allowed the coaddition of time slices over a large number of pulsar periods to build up quantifiable spectroscopic data when observing in a flux-limited regime. 相似文献
810.
Norbert Mercier Christine Hatt Michel Fontugne Jean-Louis Reyss Hlne Valladas Luc Wengler Jean-Philip Brugal Abderrahmane Ouammou Andr Weisrock 《Quaternary Geochronology》2009,4(4):326-334
The Sidi Messaoud site provides a 40 m thick sedimentary infilling of great importance for the study of environmental changes and landscape evolution during the Upper Pleistocene in the Western Sahara. In this study, chronological results obtained by the 14C, U-series and optical dating techniques are compared. Each individual age, depositional environment and post-deposition history of the various samples are evaluated, in order to explain the methodological reasons for discordances and concordances. Stratigraphic and palaeoenvironmental implications for the last 120 ka history in southwestern Morocco are also inferred: the wadi Noun gorges had been incised before MIS 5, and later, during MIS 3, the valley has been filled in with a mean sedimentation rate of 1 m/ka. 相似文献