Global urbanization projections for the Shared Socioeconomic Pathways     

《Global Environmental Change》2017

The new scenario process for climate change research includes the creation of Shared Socioeconomic Pathways (SSPs) describing alternative societal development trends over the coming decades. Urbanization is a key aspect of development that is relevant to studies of mitigation, adaptation, and impacts. Incorporating urbanization into the SSPs requires a consistent set of global urbanization projections that cover long time horizons and span a full range of uncertainty. Existing urbanization projections do not meet these needs, in particular providing only a single scenario over the next few decades, a period during which urbanization is likely to be highly dynamic in many countries. We present here a new, long-term, global set of urbanization projections at country level that cover a plausible range of uncertainty. We create SSP-specific projections by choosing urbanization outcomes consistent with each SSP narrative. Results show that the world continues to urbanize in each of the SSPs but outcomes differ widely across them, with urbanization reaching 60%, 79%, and 92% by the end of century in SSP3, SSP2, and SSP1/SSP4/SSP5, respectively. The degree of convergence in urbanization across countries also differs substantially, with largely convergent outcomes by the end of the century in SSP1 and SSP5 and persistent diversity in SSP3. This set of global, country-specific projections produces urbanization pathways that are typical of regions in different stages of urbanization and development levels, and can be extended to further elaborate assumptions about the styles of urban growth and spatial distributions of urban people and land cover occurring in each SSP.  相似文献   

China’s changing economy and emissions trajectory: following global trends     

Mukul Sanwal  Xinzhu Zheng 《Climate Policy》2018,18(1):36-41

A key climate policy issue and debate is the future trajectory of emissions of carbon dioxide of countries, their peaking dates, and rates of decline after peaking. This article analyses China’s emissions trajectory in terms of global historical trends distinguishing between industry, infrastructure, and urbanization. Growth of emissions from industrialization and infrastructure development has stabilized in 2014 with saturation levels being reached, while the process of urbanization continues with the shift of the economy to the services sector, with reduced energy use, and this is a global trend. The future trajectory of emissions will be shaped largely by growth of transport and building-related services which directly impact on and are shaped by middle-class levels of well-being. These are areas where convergence with levels of services in other urbanized countries is an important element of national policy. This global trend has not been adequately taken into account in modelling and macroeconomic analysis which ignore social processes. The article concludes that China’s 13th Five Year Plan (2016–2020) seeks to achieve a ‘moderately well-off society’ while putting a cap on total energy demand by modifying the drivers of consumption emissions compared with countries that urbanized earlier. The adoption of a public policy priority of dense mixed-use urban form, public transport, energy efficiency to enable energy system reform, and digital economy could be a model for others.

Policy relevance

The article redefines climate change in terms of social processes as urban form and notions of well-being lock-in increasing levels of future emissions of carbon dioxide. There are implications for research in assessing how best drivers of emissions can be modified without affecting well-being, including renewable and digital technologies and human behaviours that drive patterns of natural resource use as well as the identification of leverage points. There are also broader implications for replacing the development cooperation model of global climate governance to focus on new values recognizing interdependencies for sharing responsibility as well as prosperity.  相似文献   

Changes in low and high flows in the Vistula and the Odra basins: Model projections in the European‐scale context          下载免费PDF全文

Mikołaj Piniewski  Mateusz Szcześniak  Zbigniew W. Kundzewicz  Abdelkader Mezghani  Øystein Hov 《水文研究》2017,31(12):2210-2225

A number of extensive droughts and destructive floods have occurred in Poland in the last 25 years; hence, projections of low and high river flows are of considerable interest and importance. In the first part of this paper, projections of low and high flows in the rivers of the Vistula and the Odra basins (VOB region), for two future time horizons, are presented. Projections are based on the Soil and Water Assessment Tool (SWAT) hydrological model simulations driven by results of the EURO‐CORDEX experiment under Representative Concentration Pathways 4.5 and 8.5. The VOB region covers most of Poland and parts of five neighboring countries, giving this study an international relevance. In the second part of the paper, a review of projections of low and high flows in rivers in Central and Eastern Europe is presented. Despite a substantial spread of flow projections, the main message of the modelling part is that increases of both low and high flows are dominating. The magnitude of increase of low flow is considerably higher than that of high flow. In other words, future streamflow droughts are projected to be less severe, whereas, in contrast, river floods are projected to increase, which is a challenge for flood risk reduction, water management, and climate change adaptation. There is an overall agreement of our findings for the VOB region with projections of hydrological extremes from large‐scale models forced by EURO‐CORDEX results in the European‐scale studies.  相似文献   

The impact of climate change on U. K. river flows: A preliminary comparison of two generations of probabilistic climate projections     

Alison Lindsey Kay  Glenn Watts  Steven C. Wells  Stuart Allen 《水文研究》2020,34(4):1081-1088

The impacts of climate change on future river flows are a growing concern. Typically, impacts are simulated by driving hydrological models with climate model ensemble data. The U.K. Climate Projections 2009 (UKCP09) provided probabilistic projections, enabling a risk-based approach to decision-making under climate change. Recently, an update was released—UKCP18—so there is a need for information on how impacts may differ. The probabilistic projections from UKCP18 and UKCP09 are here applied using the change factor method with catchment-based hydrological modelling for 10 catchments across England. Projections of changes in median, mean, high, and low flows are made for the 2050s, using the A1B emissions scenario from UKCP09 and UKCP18 as well as the RCP4.5 and RCP8.5 emissions scenarios from UCKP18. The results show that, in all catchments for all flow measures, the central estimate of change under UKCP18 is similar to that from UKCP09 (A1B emissions). However, the probabilistic uncertainty ranges from UKCP18 are, in all cases, greater than from UKCP09, despite UKCP18 having a smaller ensemble size than UKCP09. Although there are differences between the central estimates of change using UKCP18 RCP4.5, RCP8.5 and A1B emissions, there is considerable overlap in the uncertainty ranges. The results suggest that existing assessments of hydrological impacts remain relevant, though it will be necessary to evaluate sensitive decisions using the latest projections. The analysis will aid development of advice to users of current guidance based on UKCP09 and help make decisions about the prioritization of further hydrological impacts work using UKCP18, which should also apply other products from UKCP18 like the 12-km regional data.  相似文献   

Using response surfaces to estimate impacts of climate change on flood peaks: assessment of uncertainty          下载免费PDF全文

A. L. Kay  S. M. Crooks  N. S. Reynard 《水文研究》2014,28(20):5273-5287

The potential impacts of climate change are an increasing focus of research, and ever‐larger climate projection ensembles are available, making standard impact assessments more onerous. An alternative way of estimating impacts involves response surfaces, which present the change in a given indicator for a large number of plausible climatic changes defined on a regular sensitivity domain. Sets of climate change projections can then be overlaid on the response surface and impacts estimated from the nearest corresponding points of the sensitivity domain, providing a powerful method for fast impact estimation for multiple projections and locations. However, the effect of assumptions necessary for initial response surface development must be assessed. This paper assesses the uncertainty introduced by use of a sensitivity framework for estimating changes in 20‐year return period flood peaks in Britain. This sensitivity domain involves mean annual and seasonal precipitation changes, and a number of simplifications were necessary for consistency and to reduce dimensionality. The effect of these is investigated for nine catchments across Britain, representing nine typical response surfaces (response types), using three sets of climate projections. The results show that catchments can have different causes of uncertainty and some catchments have an overall higher level of uncertainty than others. These differences are compatible with the underlying climatological and hydrological differences between the response types, giving confidence in generalization of the results. This enables the development of uncertainty allowances by response type, to be used alongside the response surfaces to provide more robust impact estimates. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

A new pseudocylindrical equal-area projection for adaptive composite map projections     

Bojan Šavrič  Bernhard Jenny 《International journal of geographical information science》2014,28(12):2373-2389

The recently introduced adaptive composite map projection technique changes the projection to the geographic area shown on a map. It is meant as a replacement for the commonly used web Mercator projection, which grossly distorts areas when representing the entire world. The original equal-area version of the adaptive composite map projection technique uses the Lambert azimuthal projection for regional maps and three alternative projections for world maps. Adaptive composite map projections can include a variety of other equal-area projections when the transformation between the Lambert azimuthal and the world projections uses Wagner’s method. To select the most suitable pseudocylindrical projection, the distortion characteristics of a pseudocylindrical projection family are analyzed, and a user study among experts in the area of map projections is carried out. Based on the results of the distortion analysis and the user study, a new pseudocylindrical projection is recommended for extending adaptive composite map projections. The new projection is equal-area throughout the transformation to the Lambert azimuthal projection and has better distortion characteristics then small-scale projections currently included in the adaptive composite map projection technique.  相似文献   

Projection of Extreme Temperatures in Hong Kong in the 21st Century          下载免费PDF全文

LEE Tsz-cheung  CHAN Kin-yu  GINN Wing-lui 《Acta Meteorologica Sinica》2011,25(1):1-20

The possible changes in the frequency of extreme temperature events in Hong Kong in the 21st century were investigated by statistically downscaling 26 sets of the daily global climate model projections (a combination of 11 models and 3 greenhouse gas emission scenarios, namely A2, A1B, and B1) of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The models’ performance in simulating the past climate during 1971–2000 has also been verified and discussed. The verification revealed that the models in general have an acceptable skill in reproducing past statistics of extreme temperature events. Moreover, the models are more skillful in simulating the past climate of the hot nights and cold days than that of the very hot days. The projection results suggested that, in the 21st century, the frequency of occurrence of extremely high temperature events in Hong Kong would increase significantly while that of the extremely low temperature events is expected to drop significantly. Based on the multi-model scenario ensemble mean, the average annual numbers of very hot days and hot nights in Hong Kong are expected to increase significantly from 9 days and 16 nights in 1980–1999 to 89 days and 137 nights respectively in 2090–2099. On the other hand, the average annual number of cold days will drop from 17 days in 1980–1999 to about 1 day in 2090–2099. About 65 percent of the model-scenario combinations indicate that there will be on average less than one cold day in 2090–2099. While all the model-emission scenarios in general have projected consistent trends in the change of temperature extremes in the 21st century, there is a large divergence in the projections between difierent model/emission scenarios. This reflects that there are still large uncertainties in the model simulation of the future climate of extreme temperature events.  相似文献   

双投影矩阵模型的方向关系组合推理研究     

顾卫杰  刘永山 《测绘科学技术学报》2014,(5)

将三维空间中的参照物体分别向xoy和xoz平面投影,得到的最小外接矩形将两个平面都划分成9个区域,用两个三行三列矩阵联合表示目标物体投影与两个参考区域的相交情况,据此提出了双投影方向关系矩阵模型。基于该模型,利用矩阵的计算性能,提出了一种三维空间方向关系的组合推理方法,解决了方向关系的组合推理问题。  相似文献   

Code as Cartography     

《The Cartographic journal》2013,50(2):129-135

Abstract

Provincial Atlas of People's Republic of China (Chung hua ien min kung wo kuo fên shêng di t'u chi). 190 x 265 mm. pp. 251 (84 pages of maps). Peking: Map Publishing Society (di t'u ch'u p'an shê), China, Oct., 1974. 6.30 Yuan  相似文献   

New measures for analysis and comparison of shape distortion in world map projections     

Melih Basaraner  Sinan Cetinkaya 《制图学和地理信息科学》2013,40(6):518-531

ABSTRACT

World maps can have quite different depictions of reality depending on the projection adopted, and this can influence our perception of the world. In this respect, shape is a significant property that needs to be considered, especially when representing large regions in general-purpose world maps. A map projection distorts most geometric properties (area, distance, direction/angle, shape, and specific curves) and usually preserves a single property or provides a compromise between different properties when transforming terrestrial features from globe to plane. The distortions are mainly classified based on area, distance and direction/angle and analyzed with Tissot’s theorem. However, this theorem offers a local (pointwise) solution, so the distortion assessment is valid at infinitesimal scale (i.e. for very small regions). For this reason, different approaches are required to analyze the distortions at finite scale (i.e. for larger regions). However, there are very few attempts at analyzing and comparing shape distortion of landmasses in world map projections owing to the fact that shape measurement is difficult and usually involves measuring different characteristics. Seeking to fill this gap, in this study, compactness and elongation distortion measures are introduced. In this regard, 16 world map projections are analyzed and compared with these distortion measures in a GIS environment, based on map datasets of continents and countries. An analysis of the effect of the levels of detail of the datasets is also presented.  相似文献