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101.
102.
103.
Infinite uncertainty,forgotten feedbacks,and cost-benefit analysis of climate policy 总被引:1,自引:1,他引:1
Tol (2003) questioned the applicability of expected cost-benefit analysis to global mitigation policy when he found evidence that the
uncertainty surrounding estimates of the marginal damage of climate change could be infinite even if total damages were finite.
Yohe (2003) suggested that this problem could be alleviated if international development aid were directed at eliminating the source
of the problem – climate induced negative growth rates in a few regions along a handful of troublesome scenarios. The hypothesis
about adding a second policy lever to the climate policy calculus is shown to hold, though perhaps not as robustly as originally
thought. A portfolio of international policies with at least two independent tools can avoid infinite uncertainty on the margins
and the associated implications for global mitigation policy at a reasonable price even in the relatively unlikely event that
climate change causes negative economic growth in a region or two.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
104.
The Marmes Rockshelter archaeological site in southeastern Washington state contains a > 11 kyr stratigraphic record that was excavated in the 1960s but only recently analyzed in detail. We present the results of physical, chemical, and isotopic analyses of archived Marmes sediments from rockshelter, hillslope, and floodplain locations. Multiple lines of evidence including éboulis production, soil chemistry, and δ13C and δ18O signatures in soil organic matter and calcium carbonate suggest that relatively cool, moist conditions 10,600 to 9700 14C yr BP were followed by relatively warm and dry conditions as early as 9000 14C yr BP. Warm and dry conditions extended to the late Holocene, followed by a return to cooler and moister climate. The limited range of δ13C and δ18O values in Marmes paleosols suggests that the magnitude of moisture and temperature shifts was locally buffered in the lower Snake River Canyon but adequate to generate significant changes in sedimentation and soil formation, possibly due to nonlinear geological and pedological processes. These buffered canyon environments were well suited for establishing residential bases associated with foraging and logistical collecting strategies and may have minimized the influence of climate changes in food resource abundance. 相似文献
105.
In situ measurements of 60Fe-60Ni and 53Mn-53Cr isotopic systems with an ion microprobe have been carried out for sulfide assemblages from unequilibrated enstatite chondrites (UECs). Evidence for the initial presence of 60Fe has been observed in nine sulfide inclusions from three UECs: ALHA77295, MAC88136, and Qingzhen. The inferred initial (60Fe/56Fe) [(60Fe/56Fe)0] ratios show a large variation range, from ∼2 × 10−7 to ∼2 × 10−6. The sulfide inclusions with high Fe/Ni ratios yield (60Fe/56Fe)0 ratios of ∼(2-7) × 10−7, similar to most of the (60Fe/56Fe)0 values of troilite and pyroxene observed in unequilibrated ordinary chondrites (UOCs). Inclusions with high inferred (60Fe/56Fe)0 ratios (∼1-2 × 10−6) have low Fe/Ni ratios and the magnitude of the 60Ni excesses is similar in two MAC88136 assemblages in spite of a difference of a factor of two in their Fe/Ni ratios. The inferred high (60Fe/56Fe)0 ratios were probably the result of Fe-Ni re-distribution in the sulfides during later alteration processes.The 53Mn-53Cr system was measured in five of the sulfide assemblages that were examined for their 60Fe-60Ni systematics. The 53Mn-53Cr isochrons yielded variable initial (53Mn/55Mn) [(53Mn/55Mn)0] ratios from ∼(2-7) × 10−7. There is no obvious correlation between the (60Fe/56Fe)0 and (53Mn/55Mn)0 ratios. The variable 53Mn-53Cr isochrons probably also indicate later disturbance to the isotopic systems in these sulfides. Even though no chronological information can be extracted from the 60Fe-60Ni and 53Mn-53Cr systems in these UEC sulfides, our results indicate that 60Fe was present in the enstatite chondrite formation region of the early Solar System. 相似文献
106.
Gary M. McMurtry David R. Tappin Peter N. Sedwick Ian Wilkinson Jan Fietzke Bruce Sellwood 《Sedimentary Geology》2007,200(3-4):155-165
Deposits of coral-bearing, marine shell conglomerate exposed at elevations higher than 20 m above present-day mean sea level (MSL) in Bermuda and the Bahamas have previously been interpreted as relict intertidal deposits formed during marine isotope stage (MIS) 11, ca. 360–420 ka before present. On the strength of this evidence, a sea level highstand more than 20 m higher than present-day MSL was inferred for the MIS 11 interglacial, despite a lack of clear supporting evidence in the oxygen-isotope records of deep-sea sediment cores. We have critically re-examined the elevated marine deposits in Bermuda, and find their geological setting, sedimentary relations, and microfaunal assemblages to be inconsistent with intertidal deposition over an extended period. Rather, these deposits, which comprise a poorly sorted mixture of reef, lagoon and shoreline sediments, appear to have been carried tens of meters inside karst caves, presumably by large waves, at some time earlier than ca. 310–360 ka before present (MIS 9–11). We hypothesize that these deposits are the result of a large tsunami during the mid-Pleistocene, in which Bermuda was impacted by a wave set that carried sediments from the surrounding reef platform and nearshore waters over the eolianite atoll. Likely causes for such a megatsunami are the flank collapse of an Atlantic island volcano, such as the roughly synchronous Julan or Orotava submarine landslides in the Canary Islands, or a giant submarine landslide on the Atlantic continental margin. 相似文献
107.
应用双差定位方法(hypodd)对北美Loma Prieta 地区的分属于3个地震丛集的47个地震进行了精确定位.采用交叉谱法精确求取信号的走时差;同时采用人机联做方式在时域调整、修正按自动方式无法准确提取时差的信号,确保每个事件对的走时差精度.重定位后,在几百米的范围内,原来相互重叠的震源位置聚集为三个明显分离的丛集;水平方向的相对位置平均误差为8.5米,震源深度方向的平均误差为23.4 m. 相似文献
108.
Influence of the Atlantic Multidecadal Oscillation on the Winter Climate of East China 总被引:11,自引:0,他引:11
The Atlantic Multidecadal Oscillation (AMO), the multidecadal variation of North Atlantic sea surface temperature (SST), exhibits an oscillation with a period of 65-80 years and an amplitude of 0.4℃. Observational composite analyses reveal that the warm phase AMO is linked to warmer winters in East China, with enhanced precipitation in the north of this region and reduced precipitation in the south, on multidecadal time scales. The pattern is reversed during the cold phase AMO. Whether the AMO acts as a forcing of the multidecadal winter climate of East China is explored by investigating the atmospheric response to warm AMO SST anomalies in a large ensemble of atmospheric general circulation model (AGCM) experiments. The results from three AGCMs are consistent and suggest that the AMO warmth favors warmer winters in East China. This influence is realized through inducing negative surface air pressure anomalies in the hemispheric-wide domain extending from the midlatitude North Atlantic to midlatitude Eurasia. These negative surface anomalies favor the weakening of the Mongolian Cold High, and thus induce a weaker East Asian Winter Monsoon. 相似文献
109.
V -band polarimetric observations of HD 108 were obtained during 1994 August and September. This is the first time that the temporal polarimetric variability of this star has been investigated. Its percentage polarization and position angle vary randomly, and no evidence of its proposed binary nature is detected. The random variability is consistent with that seen for previously observed Wolf–Rayet stars and OB supergiants. Nightly variations do show some systematic behaviour consistent with the blob ejection model of Underhill & Fehey (1984). From the data it is estimated that the mass-loss rate resulting from blobs is ∼1-10−7 M⊙ yr−1 . The total mass-loss rate of the star is estimated to be ∼1-10−5 M⊙ yr−1 . The stellar rotation rate is estimated to be V rot ∼400 km s−1 with an inclination of i <20c. The data are also interpreted in terms of perturbations occurring in an equatorial disc plus bipolar jets viewed equatorially (Underhill 1994). It is found that the perturbation mass-loss rate is about ∼3-10−7 M⊙ yr−1 , giving a total mass-loss rate for the star of 13-10−5 M⊙ yr−1 . Both models are consistent with HD 108 being an OB supergiant or of the class Ofpe/WR9. 相似文献
110.
The biology, ecology, biogeography, phylogeny, and evolution of sand-dwelling scorpions are reviewed. We present general features of sand that form the ecological theatre on which psammophiles have evolved. Sand scorpions, compared to those that live off sand, are not very diverse in any one local habitat, although they are often relatively abundant. Worldwide, they are represented by 29 genera, 11 of which exist exclusively in sand. Endemic genera belong to non-related families, suggesting that psammophilic adaptations evolvedin situin different sand deserts of the world. 相似文献