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21.
Abstract This article presents a set of multi-gas emission pathways for different CO2-equivalent concentration stabilization levels, i.e. 400, 450, 500 and 550 ppm CO2-equivalent, along with an analysis of their global and regional reduction implications and implied probability of achieving the EU climate target of 2°C. For achieving the 2°C target with a probability of more than 60%, greenhouse gas concentrations need to be stabilized at 450 ppm CO2-equivalent or below, if the 90% uncertainty range for climate sensitivity is believed to be 1.5–4.5°C. A stabilization at 450 ppm CO2-equivalent or below (400 ppm) requires global emissions to peak around 2015, followed by substantial overall reductions of as much as 25% (45% for 400 ppm) compared to 1990 levels in 2050. In 2020, Annex I emissions need to be approximately 15% (30%) below 1990 levels, and non-Annex I emissions also need to be reduced by 15–20% compared to their baseline emissions. A further delay in peaking of global emissions by 10 years doubles maximum reduction rates to about 5% per year, and very probably leads to high costs. In order to keep the option open of stabilizing at 400 and 450 ppm CO2-equivalent, the USA and major advanced non-Annex I countries will have to participate in the reductions within the next 10–15 years. 相似文献
22.
Malte Willmes Dennis Reiss Harald Hiesinger Michael Zanetti 《Planetary and Space Science》2012,60(1):199-206
The mid- and high-latitudes of Mars are covered by a smooth young mantle that is interpreted as an atmospherically derived air-fall deposit of ice and dust related to recent climate changes. In order to determine relative and absolute ages of this surface unit within the southern hemisphere, a systematic survey of all available HiRISE and CTX images in the Malea Planum region from 55–60°S latitude and 50–70°E longitude was performed and the distribution and the morphology of small impact craters on the mantle deposit were investigated. Using crater size-frequency measurements, we derived absolute model ages of ～3–5 Ma for the surface of the mantle, immediately south of the Hellas basin rim. Morphologic observations of the mantle, its fresh appearance, very low number of craters, and superposition on older units support this very young Amazonian age. Nearly all observed craters on the smooth mantle in Malea Planum are small and show signs of erosion, evidence for the ongoing modification of the ice–dust mantle. However, this modification has not been strong enough to reset the surface age. Compared to the ice–dust mantle at higher latitudes in the northern and southern hemisphere, the surface of the mantle in Malea Planum is older and thus has been relatively stable during obliquity changes in the last ～3–5 Ma. This is consistent with the hypothesis that the ice–dust mantle is a complex surface deposit of different layers, that shows a strong latitude dependence in morphology and has been deposited and degraded at different times in martian history. 相似文献
23.
Malte C. Ebach Anthony C. Gill David M. Williams 《Astrophysics and Space Science》2008,317(3-4):143-144
Biogeography, the study of organismal distribution, adheres to the same basic reasoning no matter where organisms are distributed. Wickramasinghe and Wickramasinghe (Astrophys. Space Sci. doi:10.1007/s10509-008-9851-2), however, are possibly the first to propose a mechanism of distribution for extraterrestrial organisms, thus venturing into the uncharted realm of astrobiogeography. The same logic used in the study of distributions on Earth applies to those of extraterrestrial microbes. Herein we attempt to introduce some pitfalls common in biogeography for those venturing into the new study of astrobiogeography. 相似文献
24.
Aimée J. D. Pelletier Dennis E. Jelinski Malte Treplin Martin Zimmer 《Estuaries and Coasts》2011,34(4):863-871
Sandy beaches are characterised by heterogeneously distributed food sources both in time and space. The major energy supply
is derived from marine subsidies in the form of beach-cast macrophyte wrack. Wrack patches are short-lived, and their position
on the beaches varies with tidal and seasonal cycles as well as weather conditions. Little is known about how sandy beach
inhabitants orient themselves towards, and colonise, wrack patches. In a series of field studies on islands off Vancouver
Island (British Columbia, Canada), colonisation patterns of wrack patches by beach fleas and sand hoppers (Amphipoda: Talitridae),
the most abundant macrofaunal detritivores, were studied. As indicated by colonisation of experimental patches of wrack and
wrack surrogates that were either visible or buried in the sand, beach fleas (Traskorchestia traskiana) rely on olfactory cues for locating freshly deposited wrack patches in their patchy and dynamic habitat. Dense colonisation
of freshly deposited algal wrack generally occurred within less than 1 h but depended upon the tidal height of wrack patches.
Beach flea density in freshly deposited wrack patches increased with increasing tidal height. By contrast, sand hoppers (Megalorchestia californiana) colonised freshly deposited wrack patches in densities that decreased with tidal height. Discussing these interspecific
differences, we provide a primer for future detailed studies on transport of matter along the marine–terrestrial gradient
of sand beaches. 相似文献
25.
26.
Data from global and regional climate models refer to grid cells and, hence, are basically different from station data. This particularly holds for variables with enhanced spatio-temporal variability like precipitation. On the other hand, many applications like for instance hydrological models require atmospheric data with the statistical characteristics of station data. Here, we present a dynamical-statistical tool to construct virtual station data based on regional climate model output for tropical West Africa. This weather generator (WEGE) incorporates daily gridded rainfall from the model, an orographic term and a stochastic term, accounting for the chaotic spatial distribution of local rain events within a model grid box. In addition, the simulated probability density function of daily precipitation is adjusted to available station data in Benin. It is also assured that the generated data are still consistent with other model parameters like cloudiness and atmospheric circulation. The resulting virtual station data are in excellent agreement with various observed characteristics which are not explicitly addressed by the WEGE algorithm. This holds for the mean daily rainfall intensity and variability, the relative number of rainless days and the scaling of precipitation in time. The data set has already been used successfully for various climate impact studies in Benin. 相似文献
27.
Global and regional evolution of short-lived radiatively-active gases and aerosols in the Representative Concentration Pathways 总被引：3，自引：0，他引：3
Jean-Fran?ois Lamarque G. Page Kyle Malte Meinshausen Keywan Riahi Steven J. Smith Detlef P. van Vuuren Andrew J. Conley Francis Vitt 《Climatic change》2011,109(1-2):191-212
In this paper, we discuss the results of 2000?C2100 simulations following the emissions associated with the Representative Concentration Pathways (RCPs) with a chemistry-climate model, focusing on the changes in 1) atmospheric composition (troposphere and stratosphere) and 2) associated environmental parameters (such as nitrogen deposition). In particular, we find that tropospheric ozone is projected to decrease (RCP2.6, RCP4.5 and RCP6) or increase (RCP8.5) between 2000 and 2100, with variations in methane a strong contributor to this spread. The associated tropospheric ozone global radiative forcing is shown to be in agreement with the estimate used in the RCPs, except for RCP8.5. Surface ozone in 2100 is projected to change little compared from its 2000 distribution, a much-reduced impact from previous projections based on the A2 high-emission scenario. In addition, globally-averaged stratospheric ozone is projected to recover at or beyond pre-1980 levels. Anthropogenic aerosols are projected to strongly decrease in the 21st century, a reflection of their projected decrease in emissions. Consequently, sulfate deposition is projected to strongly decrease. However, nitrogen deposition is projected to increase over certain regions because of the projected increase in NH3 emissions. 相似文献
28.
The Eastern Weddell Ice Shelves (EWIS) are believed to modify the water masses of the coastal current and thus preconditions
the water mass formation in the southern and western Weddell Sea. We apply various ocean warming scenarios to investigate
the impact on the temperature–salinity distribution and the sub-ice shelf melting in the Eastern Weddell Sea. In our numerical
experiments, the warming is imposed homogeneously along the open inflow boundaries of the model domain, leading to a warming
of the warm deep water (WDW) further downstream. Our modelling results indicate a weak quadratic dependence of the melt rate
at the ice shelf base on the imposed amount of warming, which is consistent with earlier studies. The total melt rate has
a strong dependence on the applied ocean warming depth. If the warming is restricted to the upper ocean (above 1,000 m),
the water column (aside from the mixed surface layer) in the vicinity of the ice shelves stabilises. Hence, reduced vertical
mixing will reduce the potential of Antarctic Bottom Water formation further downstream with consequences on the global thermohaline
circulation. If the warming extends to the abyss, the WDW core moves significantly closer to the continental shelf break.
This sharpens the Antarctic Slope Front and leads to a reduced density stratification. In contrast to the narrow shelf bathymetry
in the EWIS region, a wider continental shelf (like in the southern Weddell Sea) partly protects ice shelves from remote ocean
warming. Hence, the freshwater production rate of, e.g., the Filchner–Ronne Ice Shelf increases much less compared with the
EWIS for identical warming scenarios. Our study therefore indicates that the ice-ocean interaction has a significant impact
on the temperature-salinity distribution and the water column stability in the vicinity of ice shelves located along a narrow
continental shelf. The effects of ocean warming and the impact of increased freshwater fluxes on the circulation are of the
same order of magnitude and superimposed. Therefore, a consideration of this interaction in large-scale climate studies is
essential. 相似文献
29.
Malte Drobe Mnica G. Lpez de Luchi Andr Steenken Robert Frei Rudolf Naumann Siegfried Siegesmund Klaus Wemmer 《Journal of South American Earth Sciences》2009,28(3):239-262
Provenance studies have been performed utilising major and trace elements, Nd systematics, whole rock Pb–Pb isotopes and zircon U/Pb SHRIMP data on metasedimentary rocks of the Sierra de San Luis (Nogolí Metamorphic Complex, Pringles Metamorphic Complex, Conlara Metamorphic Complex and San Luis Formation) and the Puncoviscana Formation of the Cordillera Oriental. The goal was the characterisation of the different domains in the study area and to give insights to the location of the source rocks. An active continental margin setting with typical composition of the upper continental crust is depicted for all the complexes using major and trace elements. The Pringles Metamorphic Complex shows indications for crustal recycling, pointing to a bimodal provenance. Major volcanic input has to be rejected due to Th/Sc, Y/Ni and Cr/V ratios for all units. The εNd(540 Ma) data is lower for the San Luis Formation and higher for the Conlara Metamorphic Complex, as compared to the other units, in which a good consistency is given. This is similar to the TDM ages, where the metapsammitic samples of the San Luis Formation are slightly older. The spread of data is largest for the Pringles Metamorphic Complex, again implying two different sources. The whole rock 207Pb/206Pb isotopic data lies in between the South American and African sources, excluding Laurentian provenances. The whole rock Pb–Pb data is almost indistinguishable in the different investigated domains. Only the PMC shows slightly elevated 208Pb/204Pb values. Possible source rocks for the different domains could be the Quebrada Choja in the Central Arequipa–Antofalla domain, the Southern domain of the Arequipa–Antofalla basement, the Brazilian shield or southern Africa. Zircon SHRIMP data point to a connection between the Puncoviscana Formation and the Conlara Metamorphic Complex. Two maxima around 600 Ma and around 1000 Ma have been determined. The Nogolí Metamorphic Complex and the Pringles Metamorphic Complex show one peak of detrital zircons around 550 Ma, and only a few grains are older than 700 Ma. The detrital zircon ages for the San Luis Formation show age ranges between 590 and 550 Ma. A common basin can be assumed for the Conlara Metamorphic Complex and the Puncoviscana Formation, but the available data support different sources for the rest of the Complexes of the Sierra de San Luis. These share the diminished importance or the lack of the Grenvillian detrital peak, a common feature for the late Cambrian–early Ordovician basins of the Eastern Sierras Pampeanas, in contrast to the Sierras de Córdoba, the PVF and the Conlara Metamorphic Complex. 相似文献
30.
A set of 61 normal modes with periods between 7.8 and 133.1 h has been calculated, using a 1° model of the global ocean, including
the Arctic Ocean. The model explicitly considers frictional forces and ocean self-attraction and loading effects. The latter
effects have generally been taken into account by parameterization, but for some modes the effects have also been considered
fully. Due to friction, the computed eigenfrequencies are complex, exhibiting also the varying dissipative properties of the
modes and their dependence on the distribution of potential and kinetic energies over the oceanic regions. In detail, gravity
modes having periods less then 80 h and dominating the semi-diurnal and the diurnal tides, topographically controlled vorticity
modes with periods longer than diurnal, and two planetary vorticity modes with periods of 96.8 and 119.4 h have been identified.
These planetary vorticity modes have their energies distributed over Pacific, Atlantic, and Indian Oceans, while the other
modes with periods longer than 80 h, as vorticity modes, have their energies concentrated on topographic structures of restricted
extension. The modes are discussed with respect to their wave properties, e.g., concerning quasi-standing-wave resonances
and to the appearance of Kelvin waves of different orders and trapped by different coastlines. In particular, the relevance
of specific modes for the development of the fields of the most important semi-diurnal and diurnal tidal constituents is investigated. 相似文献