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101.
The issue of climate change required the development of the Special Report on Emission Scenarios (SRES) by the IPCC. The complexity
of the subject and the unique science-policy relation resulted in confusion and discussions appeared in popular media like
The Economist. This paper reviews scenario literature and SRES, identifies the most vulnerable elements in the communication
of SRES. In the communication of GHG emission scenarios through SRES, the weaknesses that have been identified by the authors
of this paper are the normative character of climate change assessment, the plausibility of the scenarios, and the risk of
simplification of complex messages. The causes of these communicative issues have been identified as the intrinsic difficulties
of interdisciplinary science, the uniqueness of the science-policy relation, and the need for a high degree of transparency.
This paper suggests improving future communication of complex messages from scientists to their audience by means of clear
reasoning when communicating with non-scientists, explicitly normative emission scenarios, and increased stakeholder participation
in scenario development.
Based on a presentation at the “IIASA-YSSP uncertainty seminars,” 22 July 2004, and the discussions thereafter. 相似文献
102.
During the mid‐Holocene, the first large‐scale civilizations emerged in lower alluvial systems after a marked decrease in sea‐level rise at 7–6 kyr. We show that as the landscapes of deltas and lower alluvial plains adjusted to this decrease in the rate of relative sea‐level rise, the abundance and location of resources available for human exploitation changed as did the network of waterways. This dynamic environmental evolution contributed to archaeological changes in the three fluvio‐deltaic settings considered herein: Egypt, Mesopotamia, and the Huang He in China. Specifically, an increase in the scale and intensity of agricultural practice, and the focussing of power toward a single city can be interpreted as responses to these environmental changes. Other archaeological observations, and the cultural trajectories leading to the formation of the Primary States also need to be considered in light of these evolving landscapes. 相似文献
103.
Direct evidence of the feedback between climate and weathering 总被引:1,自引:0,他引:1
Sigurdur R. Gislason Eric H. Oelkers Eydis S. Eiriksdottir Marin I. Kardjilov Gudrun Gisladottir Bergur Sigfusson Arni Snorrason Sverrir Elefsen Jorunn Hardardottir Peter Torssander Niels Oskarsson 《Earth and Planetary Science Letters》2009,277(1-2):213-222
Long-term climate moderation is commonly attributed to chemical weathering; the higher the temperature and precipitation the faster the weathering rate. Weathering releases divalent cations to the ocean via riverine transport where they promote the drawdown of CO2 from the atmosphere by the precipitation and subsequent burial of carbonate minerals. To test this widely-held hypothesis, we performed a field study determining the weathering rates of 8 nearly pristine north-eastern Iceland river catchments with varying glacial cover over 44 years. The mean annual temperature and annual precipitation of these catchments varied by 3.2 to 4.5 °C and 80 to 530%, respectively during the study period. Statistically significant linear positive correlations were found between mean annual temperature and chemical weathering in all 8 catchments and between mean annual temperature and both mechanical weathering and runoff in 7 of the 8 catchments. For each degree of temperature increase, the runoff, mechanical weathering flux, and chemical weathering fluxes in these catchments are found to increase from 6 to 16%, 8 to 30%, and 4 to 14% respectively, depending on the catchment. In contrast, annual precipitation is less related to the measured fluxes; statistically significant correlations between annual precipitation and runoff, mechanical weathering, and chemical weathering were found for 3 of the least glaciated catchments. Mechanical and chemical weathering increased with time in all catchments over the 44 year period. These correlations were statistically significant for only 2 of the 8 catchments due to scatter in corresponding annual runoff and average annual temperature versus time plots. Taken together, these results 1) demonstrate a significant feedback between climate and Earth surface weathering, and 2) suggest that weathering rates are currently increasing with time due to global warming. 相似文献
104.
We present a new, fast and versatile method, the lateral parameter correlation method, of invoking lateral smoothness in model sections of one-dimensional (1D) models. Modern, continuous electrical and electromagnetic methods are capable of recording very large data sets and except for a few cases, standard inversion methodology still relies on 1D models. In environments where the lateral rate of change of resistivity is small, 1D inversion can be justified but model sections of concatenated 1D models do not necessarily display the expected lateral smoothness.
The lateral parameter correlation method has three steps. First, all sounding data are inverted individually. Next, a laterally smooth version of each model parameter, one at a time, is found by solving a simple constrained inversion problem. Identity is postulated between the uncorrelated and correlated parameters and the equations are solved including a model covariance matrix. As a last step, all sounding data are inverted again to produce models that better fit the data, now subject to constraints by including the correlated parameter values as a priori values. Because the method separates the inversion from the correlation it is much faster than methods where the inversion and correlation are solved simultaneously, typically with a factor of 200–500.
Theoretical examples show that the method produces laterally smooth model sections where the main influence comes from the well-determined parameters in such a way that problems with equivalence and poor resolution are alleviated. A field example is presented, demonstrating the improved resolution obtained with the lateral parameter correlation method. The method is very flexible and is capable of coupling models from inversion of different data types and information from boreholes. 相似文献
The lateral parameter correlation method has three steps. First, all sounding data are inverted individually. Next, a laterally smooth version of each model parameter, one at a time, is found by solving a simple constrained inversion problem. Identity is postulated between the uncorrelated and correlated parameters and the equations are solved including a model covariance matrix. As a last step, all sounding data are inverted again to produce models that better fit the data, now subject to constraints by including the correlated parameter values as a priori values. Because the method separates the inversion from the correlation it is much faster than methods where the inversion and correlation are solved simultaneously, typically with a factor of 200–500.
Theoretical examples show that the method produces laterally smooth model sections where the main influence comes from the well-determined parameters in such a way that problems with equivalence and poor resolution are alleviated. A field example is presented, demonstrating the improved resolution obtained with the lateral parameter correlation method. The method is very flexible and is capable of coupling models from inversion of different data types and information from boreholes. 相似文献
105.
Jens M. Turowski Niels Hovius Hsieh Meng‐Long Dimitri Lague Chen Men‐Chiang 《地球表面变化过程与地形》2008,33(3):353-363
Lateral erosion in bedrock rivers is an important control on the shape of channel cross‐sections, and the coupling of channels and hillslopes. Recent observations link lateral erosion to the variability of flow. We propose two mechanisms to explain this. One is based on changing shear stress distributions within the channel with varying flood level, the other on the competition between cover and tool effects in fluvial bedrock erosion. We assess these processes for the Liwu River, Taiwan, and conclude that cover and tool effects dominate the partitioning of lateral and vertical erosion in this case. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
106.
Sanne Lorentzen Carita Augustsson Jens Jahren Johan P. Nystuen Niels H. Schovsbo 《Basin Research》2019,31(6):1098-1120
Lower Cambrian quartz arenitic deposits have a worldwide occurrence. In this study, petrographic and mineralogical analyses were carried out on samples from the quartz‐rich Ringsaker Member of the Vangsås Formation from southern Norway and the corresponding Hardeberga Formation from southern Sweden and on the Danish island of Bornholm. The quartz arenite is almost completely quartz cemented and has an average intergranular volume of 30%. The quartz cement is the dominating cause for porosity loss. Dissolution along stylolites and microstylolites is suggested to be the primary and secondary source for the quartz cement respectively. The quartzose sandstone from southern Norway was severely cemented prior to the Caledonian Orogeny, thus limiting the tectonic influence on diagenesis during thrusting. For most samples, authigenic clay minerals and detrital phyllosilicates represent ca. 5% of the present‐day composition. This, together with a low feldspar content, of on average 4%, indicates that the sediment was extremely quartz‐rich already during deposition. The low amount of feldspar prior to burial and the formation of early diagenetic kaolinite point to weathering, sediment reworking and early diagenesis act as important controls on sediment maturity. The large variation in clay‐mineral and feldspar content between the localities, as well as within the sandstone successions, can be explained by different palaeogeography on the shelf during deposition and subsequently dissimilar subjection to reworking and early diagenetic processes. Weathering in the provenance area, reworking in the depositional shallow‐marine environment and meteoric flushing during the burial stage are suggested to explain the high mineralogical maturity of the lower Cambrian sandstone from southwestern Baltica. These processes may generally account for similar quartz‐rich shallow‐marine sandstone units, deposited as a result of intensive continental denudation and during temperate to subtropical and moderately humid conditions. 相似文献
107.
Niels Schütze Sebastian Kloss Franz Lennartz Ahmed Al Bakri Gerd H. Schmitz 《Environmental Earth Sciences》2012,65(5):1511-1521
In this contribution, we introduce a stochastic framework for decision support for optimal planning and operation of water
supply in irrigation. This consists of (1) a weather generator for simulating regional impacts of climate change on the basis
of IPCC scenarios, (2) a tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water
supply, (3) a mechanistic model for simulating water transport and crop growth in a sound manner, and (4) a kernel density
estimator for estimating stochastic productivity, profit, and demand functions by a nonparametric method. As a result of several
simulation/optimization runs within the framework, we present stochastic crop-water production functions (SCWPF) for different
crops which can be used as a basic tool for assessing the impact of climate variability on the risk for the potential yield
for specific crops and specific agricultural areas. A case study for an agricultural area in the Al Batinah region of the
Sultanate of Oman is used to illustrate these methodologies. In addition, microeconomic impacts of climate change and the
vulnerability of the agro-ecological system are discussed. 相似文献
108.
Ole Humlum Birger Ulf Hansen Niels Nielsen Hanne H. Christiansen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):113-121
An automatic meteorological station has been operating at the Arctic Station (69°15'N, 53°31'W) in West Greenland since 1990. This paper summarises meteorological parameters during 1998, including snow cover, ground temperatures and active layer development, and presents comments on the local permafrost thickness. Abstract Active layer monitoring in Greenland was started in 1996 and 1997, and forms part of the Circumpolar Active Layer Monitoring (CALM) Network of the International Permafrost Association (IPA). The results of the first years of this monitoring of thaw progression and maximum active layer thickness in two Greenlandic permafrost areas are presented. Two sites are in the continuous permafrost zone at Zackenberg in NE Greenland (74 °N), and one at Disko Island in W Greenland (69 °N), at the border between discontinuous and continuous permafrost. The data collected at Zackenberg demonstrate interannual variation in the timing of thaw progression in the monitoring grid holding a seasonal snowpatch, while there is less variation in the horizontal grid without a snowpatch. The maximum active layer thickness for the two Zackenberg grids is more or less consistent for the first three years with averages from 58 to 66 cm in mid and late August. At Disko the active layer reached 71 cm in mid August 1998. Spatially the distribution of the maximum, annual active layer thickness within the grids is concordant. 相似文献
109.
Christian Christiansen Troels Aagaard Jesper Bartholdy Merete Christiansen Jørgen Nielsen Niels Nielsen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):107-126
Average sea-level rise in the northern part of the Danish Wadden Sea has been 1.3 mm a?1 during the last 100 years but during the last 25 years a rise of 4.2 mm a?1 was observed. Concurrent with the recent sea-level rise the Skallingen barrier spit has migrated landward by 3–5 m a?1. Long term sediment budgets for each of the morphological units involved in the migration are reviewed (e.g. onshore in the shore face +90.000 m3 a?1, longshore -641.000 m3 a?1, foredunes +65,000 m3 a?1, overwash fan including shorenormal dunes +11,000 m3 a?1, spit terminus -96,000 m3 a?1, tidal flat + 10,000 m3 a?1 and backbarrier salt marsh +33,000 m3 a?1) and used to establish the relative importance of sediment transport processes involved in barrier migration. Strong interannual variations exist in the long term budget making evaluation of barrier behaviour based on short term measurements doubtful. In a cross shore sense the barrier spit is accreting in spite of the sea level rise. This is specially pronounced at an active overwash fan. However, due to substantial sediment losses to longshore transport the barrier, gets narrower and shorter during its transgressive behaviour. This may indicate that preservation of barriers in the geological record during rapid sea level rise is promoted when sediment loss to longshore transport is insignificant. 相似文献
110.
Morten Rasch Niels Nielsen Christian Christiansen Thomas Balstrøm Robert Gilbert Joseph Desloges 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):1-11
Measurements of discharge and suspended sediment and organic matter yield from nine different drainage basins on the island Disko in central West Greenland were carried out in the period 19–30 July 1997. A series of landscape properties (glacier cover, altitude, slope, aspect and vegetation cover) were measured for each drainage basin from a digital elevation model and a satellite image. Principal Component Analysis and regression statistics have been used to examine which landscape parameters dominate the measured discharges and yields. It is concluded that differences in suspended sediment and organic matter yield between the drainage basins can be explained by the measured morphometric properties while differences in water run-off can not. Glacier cover percentage and percent area above 800 m a.s.l. were the most important parameters influencing suspended sediment and organic matter yield in the drainage basins on Disko during the study period. 相似文献