气候变化国家评估报告（II）：气候变化的影响与适应

已经观测到的气候变化影响是显著的、多方面的。各个领域和地区都存在有利和不利影响,但以不利影响为主,未来的气候变暖将会对中国的生态系统、农业以及水资源等部门和沿海地区产生重大的不利影响。采取适应措施可以减轻气候变化的不利影响,应将适应气候变化的行动逐步纳入国民经济和社会发展的中长期规划中。由于我国科学研究的相对不足和科学认识能力的局限,目前的气候变化影响评估方法和结果还存在很大的不确定性。应当加强区域适应气候变化的案例研究、扩大研究领域、加强极端天气、气候事件影响的研究,以降低影响评估的不确定性,并提出切实可行的适应对策。     

Adapting water resources management to global climate change

This paper provides an overview of the impact of global climate change on water resources management. Changes in precipitation and temperature of the scale predicted by General Circulation Models for a doubled CO₂ level will significantly affect annual runoff, runoff variability, and seasonal runoff. These in turn will affect water supply, flood protection, hydropower generation, and environmental resources. In addition, climate change will significantly affect the geomorphic response of the watershed, increasing soil erosion and altering the hydrologic response of the watershed. These geomorphic changes will in turn affect water supply, flood hazard, and riparian ecosystems.Possible water resources management responses are identified. This includes reallocation of water supply from less valuable irrigated agriculture to municipal uses; changes in agricultural methods; increasing incentives for integrated flood management; increasing incentives for watershed management; integration of ecosystem needs in water resources planning; and the need to redesign the operation of existing water projects.     

Assessing the robustness of adaptation decisions to climate change uncertainties: A case study on water resources management in the East of England

Projections of future climate change are plagued with uncertainties, causing difficulties for planners taking decisions on adaptation measures. This paper presents an assessment framework that allows the identification of adaptation strategies that are robust (i.e. insensitive) to climate change uncertainties. The framework is applied to a case study of water resources management in the East of England, more specifically to the Anglian Water Services’ 25 year Water Resource Plan (WRP). The paper presents a local sensitivity analysis (a ‘one-at-a-time’ experiment) of the various elements of the modelling framework (e.g., emissions of greenhouse gases, climate sensitivity and global climate models) in order to determine whether or not a decision to adapt to climate change is sensitive to uncertainty in those elements.Water resources are found to be sensitive to uncertainties in regional climate response (from general circulation models and dynamical downscaling), in climate sensitivity and in climate impacts. Aerosol forcing and greenhouse gas emissions uncertainties are also important, whereas uncertainties from ocean mixing and the carbon cycle are not. Despite these large uncertainties, Anglian Water Services’ WRP remains robust to the climate change uncertainties sampled because of the adaptation options being considered (e.g. extension of water treatment works), because the climate model used for their planning (HadCM3) predicts drier conditions than other models, and because ‘one-at-a-time’ experiments do not sample the combination of different extremes in the uncertainty range of parameters. This research raises the question of how much certainty is required in climate change projections to justify investment in adaptation measures, and whether such certainty can be delivered.     

Engineering Design and Uncertainties Related to Climate Change

To explore how uncertain climate events might affect investment decisions that need to be made in the near future, this paper examines (1) the relative magnitude of the uncertainties arising from climate change on engineering design in water resources planning and (2) a restricted set of water resource planning techniques that deal with the repeated choice of investment decisions over time. The classical capacity-expansion model of operations research is exploited to show the relative impacts upon engineering design choices for variations in future demand attributable to changes in the climate or other factors and the possible shortfall of supply due to climate change. The type of engineering decisions considered in the paper are sequential, enabling adjustments to revealed uncertainty in subsequent decisions. The range of possible impacts analyzed in the paper lead to similar engineering design decisions. This result means that engineers must be on their guard with respect to under-design or over-design of systems with and without the threat of climate change, but that the sequential nature of the decision-making does not call for drastic action in the early time periods.     

Using Decision Analysis to Include Climate Change in Water Resources Decision Making

Is the prospect of possible climate change relevant to water resources decisions being made today? And, if so, how ought that prospect be considered? These questions can be addressed by decision analysis, which we apply to two investments in the Great Lakes region: a regulatory structure for Lake Erie, and breakwaters to protect Presque Isle State Park, PA. These two decisions have the elements that potentially make climate change relevant: long lived, "one shot" investments; benefits or costs that are affected by climate-influenced variables; and irreversibilities. The decision analyses include the option of waiting to obtain better information, using Bayesian analysis to detect whether climate change has altered water supplies. The analyses find that beliefs about climate change can indeed affect optimal decisions. Furthermore, ignoring the possibility of climate change can lead to significant opportunity losses—in the cases here, as much as 10% or more of the construction cost. Yet the consequences of climate uncertainty for Great Lakes management do not appear to be qualitatively different from those of other risks, and thus do not deserve different treatment. The methods of sensitivity analysis, scenario planning, and decision analysis, all of which are encouraged under US federal guidelines for water planning, are applicable. We recommend increased use of decision trees and Bayesian analysis to consider not only climate change risks, but also other important social and environmental uncertainties.     

Water resources for agriculture in a changing climate: international case studies

This integrated study examines the implications of changes in crop water demand and water availability for the reliability of irrigation, taking into account changes in competing municipal and industrial demands, and explores the effectiveness of adaptation options in maintaining reliability. It reports on methods of linking climate change scenarios with hydrologic, agricultural, and planning models to study water availability for agriculture under changing climate conditions, to estimate changes in ecosystem services, and to evaluate adaptation strategies for the water resources and agriculture sectors. The models are applied to major agricultural regions in Argentina, Brazil, China, Hungary, Romania, and the US, using projections of climate change, agricultural production, population, technology, and GDP growth.For most of the relatively water-rich areas studied, there appears to be sufficient water for agriculture given the climate change scenarios tested. Northeastern China suffers from the greatest lack of water availability for agriculture and ecosystem services both in the present and in the climate change projections. Projected runoff in the Danube Basin does not change substantially, although climate change causes shifts in environmental stresses within the region. Northern Argentina's occasional problems in water supply for agriculture under the current climate may be exacerbated and may require investments to relieve future tributary stress. In Southeastern Brazil, future water supply for agriculture appears to be plentiful. Water supply in most of the US Cornbelt is projected to increase in most climate change scenarios, but there is concern for tractability in the spring and water-logging in the summer.Adaptation tests imply that only the Brazil case study area can readily accommodate an expansion of irrigated land under climate change, while the other three areas would suffer decreases in system reliability if irrigation areas were to be expanded. Cultivars are available for agricultural adaptation to the projected changes, but their demand for water may be higher than currently adapted varieties. Thus, even in these relatively water-rich areas, changes in water demand due to climate change effects on agriculture and increased demand from urban growth will require timely improvements in crop cultivars, irrigation and drainage technology, and water management.     

气候变化国家评估报告(Ⅱ):气候变化的影响与适应

Significant and various impacts of climate change have been observed in China, showing both positive and adverse effects, dominantly the latter, in different sectors and regions. It is very likely that future climate change would cause significant adverse impacts on the ecosystems, agriculture, water resources, and coastal zones in China. Adoption of adaptive measures to climate change can alleviate the adverse impact, therefore such measures should be incorporated into the medium-and long-term national economic and social development plans. Because China has done relatively limited research on impact assessment and our understanding of climate change is incomplete, the current impact assessment methodologies used and results obtained contain many uncertainties. To reduce the uncertainties and develop effective and practical climate change adaptive measures in China, it is necessary to emphasize regional case studies on adaptive measures, enlarge the scope of climate change research, and strengthen the assessment of the impacts resulted from extreme weather/climate events.     

Impact of climate change on Pacific Northwest hydropower

The Pacific Northwest (PNW) hydropower resource, central to the region’s electricity supply, is vulnerable to the impacts of climate change. The Northwest Power and Conservation Council (NWPCC), an interstate compact agency, has conducted long term planning for the PNW electricity supply for its 2005 Power Plan. In formulating its power portfolio recommendation, the NWPCC explored uncertainty in variables that affect the availability and cost of electricity over the next 20 years. The NWPCC conducted an initial assessment of potential impacts of climate change on the hydropower system, but these results are not incorporated in the risk model upon which the 2005 Plan recommendations are based. To assist in bringing climate information into the planning process, we present an assessment of uncertainty in future PNW hydropower generation potential based on a comprehensive set of climate models and greenhouse gas emissions pathways. We find that the prognosis for PNW hydropower supply under climate change is worse than anticipated by the NWPCC’s assessment. Differences between the predictions of individual climate models are found to contribute more to overall uncertainty than do divergent emissions pathways. Uncertainty in predictions of precipitation change appears to be more important with respect to impact on PNW hydropower than uncertainty in predictions of temperature change. We also find that a simple regression model captures nearly all of the response of a sequence of complex numerical models to large scale changes in climate. This result offers the possibility of streamlining both top-down impact assessment and bottom-up adaptation planning for PNW water and energy resources.     

Climate change impacts on the energy system: a review of trends and gaps

Major transformation of the global energy system is required for climate change mitigation. However, energy demand patterns and supply systems are themselves subject to climate change impacts. These impacts will variously help and hinder mitigation and adaptation efforts, so it is vital they are well understood and incorporated into models used to study energy system decarbonisation pathways. To assess the current state of understanding of this topic and identify research priorities, this paper critically reviews the literature on the impacts of climate change on the energy supply system, summarising the regional coverage of studies, trends in their results and sources of disagreement. We then examine the ways in which these impacts have been represented in integrated assessment models of the electricity or energy system.Studies tend to agree broadly on impacts for wind, solar and thermal power stations. Projections for impacts on hydropower and bioenergy resources are more varied. Key uncertainties and gaps remain due to the variation between climate projections, modelling limitations and the regional bias of research interests. Priorities for future research include the following: further regional impact studies for developing countries; studies examining impacts of the changing variability of renewable resources, extreme weather events and combined hazards; inclusion of multiple climate feedback mechanisms in IAMs, accounting for adaptation options and climate model uncertainty.     

Monte Carlo Assessment of Sampling Uncertainty of Climate Change Impacts on Water Resources Yield in Yorkshire, England

Despite much effort over the last decade, there still remain many uncertainties in the assessed impacts of climate change on water resources. This study has carried out Monte Carlo Simulations to characterise the sampling uncertainties in assessed water resources impacts. The investigation employed data from catchments in northeast England, which incorporate water supply reservoirs. The impacts assessment used scenarios from three GCM experiments: (i) the Canadian first generation coupled model (CGCM1), (ii) the Australian first generation coupled model (CSIRO-mk2b) and (iii) the British third generation model (HadCM3). The results showed that yield impacts are subject to wide variability, irrespective of the GCM experiment, which calls for caution when using mean impacts obtained from single data record analysis for decision making.     

Adapting to Climate Impacts on the Supply and Demand for Water

The prospect of climate change adds to future water supply and demand uncertainties and reinforces the need for institutions that facilitate adaptation to changing conditions and promote efficient management of supplies and facilities. High costs and limited opportunities for increasing water supplies with dams, reservoirs, and other infrastructure have curbed the traditional supply-side approach to planning in recent decades. Although new infrastructure may be an appropriate response to climate-induced shifts in hydrologic regimes and water demands, it is difficult to plan for and justify expensive new projects when the magnitude, timing, and even the direction of the changes are unknown. On the other hand, evaluating margins of safety for long-lived structures such as dams and levees should consider the prospect that a greenhouse warming could produce greater hydrologic variability and storm extremes. Integrated river basin management can provide cost-effective increases in reliable supplies in the event of greenhouse warming. With water becoming scarcer and susceptible to variations and changes in the climate, demand management is critical for balancing future demands with supplies. Although regulatory and voluntary measures belong in a comprehensive demand management strategy, greater reliance on markets and prices to allocate supplies and introduce incentives to conserve will help reduce the costs of adapting to climate change. Federal water planning guidelines allow for consideration of plans incorporating changes in existing statutes, regulations, and other institutional arrangements that might be needed to facilitate water transfers and promote efficient management practices in response to changing supply and demand conditions.     

Climate Services for Water Resource Management in China: The Case Study of Danjiangkou Reservoir

The efficiencies and effectiveness of water resource management are inextricably linked to climate services. This study demonstrates a climate information service for Danjiangkou Reservoir, which is the largest artificial lake in Asia, facing mounting challenges for flood control, water storage, and water diversion. Unlike traditional water resource management on the basis of short-term weather forecast and runoff monitoring, subseasonal to seasonal(S2S)and annual climate predictions as well as long-term climate change projections were well used to support the decision makers in Danjiangkou Reservoir. The National Climate Center(NCC) has projected the changes of future climate and extreme events by dynamically downscaling the Coupled Model Intercomparison Project phase 5(CMIP5)projections to 25-km resolution for the long-term planning of water resource management in Danjiangkou Reservoir.Real-time climate predictions based on climate models and downscaling interpretation and application methods at different timescales were also provided to meet the specific needs of earlier predictions and spatial refinement for the short-term diversion of the reservoir. Our results show that such climate services facilitated the Diversion Center of Danjiangkou Reservoir(DCDR) to reasonably control the operational water level, increased the ecological water supply to the northern portion of China by 844 million m~3, and reduced as much as 1.67 billion m~3 of abandoned water in 2019. In the future, it is necessary to develop climate prediction methods to increase spatial and temporal resolutions and prediction skills, and enhance interactions between providers and users.     

Investigating the impact of climate change on New York City’s primary water supply

Future climate scenarios projected by three different General Circulation Models and a delta-change methodology are used as input to the Generalized Watershed Loading Functions – Variable Source Area (GWLF-VSA) watershed model to simulate future inflows to reservoirs that are part of the New York City water supply system (NYCWSS). These inflows are in turn used as part of the NYC OASIS model designed to simulate operations for the NYCWSS. In this study future demands and operation rules are assumed stationary and future climate variability is based on historical data to which change factors were applied in order to develop the future scenarios. Our results for the West of Hudson portion of the NYCWSS suggest that future climate change will impact regional hydrology on a seasonal basis. The combined effect of projected increases in winter air temperatures, increased winter rain, and earlier snowmelt results in more runoff occurring during winter and slightly less runoff in early spring, increased spring and summer evapotranspiration, and reduction in number of days the system is under drought conditions. At subsystem level reservoir storages, water releases and spills appear to be higher and less variable during the winter months and are slightly reduced during summer. Under the projected future climate and assumptions in this study the NYC reservoir system continues to show high resilience, high annual reliability and relatively low vulnerability.     

RCP情景下内蒙古黄河流域径流预估及其对水资源的影响

根据内蒙古黄河流域内72个国家气象站观测的1961—2005年和区域气候模式CCLM模拟的1961—2100年的气温和降水数据,采用BP人工神经网络模型,预估分析3种RCP情景下头道拐水文站2011—2100年流量变化,评估未来气候变化对流域水资源的可能影响。结果表明:①2011—2100年内蒙古黄河流域气温升高,降水变化不明显,年平均流量呈减少趋势,RCP2.6、RCP4.5和RCP8.5情景分别减少3.6%、2.7%和23.4%。②未来春季流量以增加为主;夏季在不同情景的变化趋势不一致;秋季在21世纪50年代前以增加为主,之后以减少为主;冬季则以减少为主。③未来流域可利用水资源呈减少趋势,尤其夏季水资源的供需矛盾加剧,以及径流季节分配发生变化,可能产生更大的春季径流。     

Is robustness really robust? How different definitions of robustness impact decision-making under climate change

Robust decision-making is being increasingly used to support environmental resources decisions and policy analysis under changing climate and society. In this context, a robust decision is a decision that is as much as possible insensitive to a large degree of uncertainty and ensures certain performance across multiple plausible futures. Yet, the concept of robustness is neither unique nor static. Multiple robustness metrics, such as maximin, optimism-pessimism, max regret, have been proposed in the literature, reflecting diverse optimistic/pessimistic attitudes by the decision maker. Further, these attitudes can evolve in time as a response to sequences of favorable (or adverse) events, inducing possible dynamic changes in the robustness metrics. In this paper, we explore the impact of alternative definitions of robustness and their evolution in time for a case of water resources system management under changing climate. We study the decisions of the Lake Como operator, who is called to regulate the lake by balancing irrigation supply and flood control, under an ensemble of climate change scenarios. Results show a considerable variability in the system performance across multiple robustness metrics. In fact, the mis-definition of the actual decision maker’s attitude biases the simulation of its future decisions and produces a general underestimation of the system performance. The analysis of the dynamic evolution of the decision maker’s preferences further confirms the potentially strong impact of changing robustness definition on the decision-making outcomes. Climate change impact assessment studies should therefore include the definition of robustness among the uncertain parameters of the problem in order to analyze future human decisions under uncertainty.     

Water Resources Implications of Global Warming: A U.S. Regional Perspective

The implications of global warming for the performance of six U.S. water resource systems are evaluated. The six case study sites represent a range of geographic and hydrologic, as well as institutional and social settings. Large, multi-reservoir systems (Columbia River, Missouri River, Apalachicola-Chatahoochee-Flint (ACF) Rivers), small, one or two reservoir systems (Tacoma and Boston) and medium size systems (Savannah River) are represented. The river basins range from mountainous to low relief and semi-humid to semi-arid, and the system operational purposes range from predominantly municipal to broadly multi-purpose. The studies inferred, using a chain of climate downscaling, hydrologic and water resources systems models, the sensitivity of six water resources systems to changes in precipitation, temperature and solar radiation. The climate change scenarios used in this study are based on results from transient climate change experiments performed with coupled ocean-atmosphere General Circulation Models (GCMs) for the 1995 Intergovernmental Panel on Climate Change (IPCC) assessment. An earlier doubled-CO₂ scenario from one of the GCMs was also used in the evaluation. The GCM scenarios were transferred to the local level using a simple downscaling approach that scales local weather variables by fixed monthly ratios (for precipitation) and fixed monthly shifts (for temperature). For those river basins where snow plays an important role in the current climate hydrology (Tacoma, Columbia, Missouri and, to a lesser extent, Boston) changes in temperature result in important changes in seasonal streamflow hydrographs. In these systems, spring snowmelt peaks are reduced and winter flows increase, on average. Changes in precipitation are generally reflected in the annual total runoff volumes more than in the seasonal shape of the hydrographs. In the Savannah and ACF systems, where snow plays a minor hydrological role, changes in hydrological response are linked more directly to temperature and precipitation changes. Effects on system performance varied from system to system, from GCM to GCM, and for each system operating objective (such as hydropower production, municipal and industrial supply, flood control, recreation, navigation and instream flow protection). Effects were generally smaller for the transient scenarios than for the doubled CO₂ scenario. In terms of streamflow, one of the transient scenarios tended to have increases at most sites, while another tended to have decreases at most sites. The third showed no general consistency over the six sites. Generally, the water resource system performance effects were determined by the hydrologic changes and the amount of buffering provided by the system's storage capacity. The effects of demand growth and other plausible future operational considerations were evaluated as well. For most sites, the effects of these non-climatic effects on future system performance would about equal or exceed the effects of climate change over system planning horizons.     

The future nexus of the Brahmaputra River Basin: Climate,water, energy and food trajectories

Advance knowledge of conflicting trajectories of water–energy–food (WEF) nexus is highly relevant for water policy and planning, especially for basins that cross national boundaries. The Brahmaputra River Basin in South Asia, home for 130 million people, is such a basin. Development of new hydropower projects, upstream water diversions and possible climate changes introduce concerns among riparian countries about future water supply for energy and food production in the basin. This study presents a new hydro-economic water system model of the basin coupled with ex post scenario analysis under the “nexus thinking” concept to identify and illustrate where development paths are in conflict. Results indicate that the ability of future development to remain free of conflict hinges mostly on the amount of precipitation falling in the basin in the future. Uncertain future precipitation along with uncertain future temperature and the unknown amount of upstream water diversion combine to strongly influence future water, energy and food production in the basin. Specifically, decreases in precipitation coupled with large upstream diversions (e.g., diversion in the territory of China) would leave one or more riparian countries unable to secure enough water to produce their desired energy and food. Future climate projected by General Circulation Models suggest a warmer and wetter climate condition in the region, which is associated with an increase in streamflow and easing of conflicts at the WEF nexus in the basin. The methodology presented here is expected to be generally useful for diagnosing the conditions that may cause water resources development goals to not be achieved due to either changes in climate or water use among competing users.     

Ecosystem Evaluation, Climate Change and Water Resources Planning

This paper considers ecosystem evaluation under conditions of climate change in the context both of the U.S. Water Resources Council's Principles and Guidelines (P&G) and the more general Federal regulations governing environmental evaluation. Federal water agencies have responsibilities for protecting aquatic ecosystems through their regulatory programs and operations and planning missions. The primary concern of water resources and aquatic ecosystems planning in the United States is on the riparian or floodplain corridors of river systems. In the context of climate change, planning for these systems focusses on adaptation options both for current climate variability and for that engendered by potential climate change.Ecosystems appear to be highly vulnerable to climate change, as described in IPCC reports. Aquatic ecosystems are likely to be doubly affected, first by thermally induced changes of global warming and second by changes in the hydrologic regime. Perhaps as much as any of the issues dealt with in this issue, the evaluation of ecosystems is linked to fundamental questions of criteria as well as to the details of the Federal environmental planning system. That system is a densely woven, interlocking system of environmental protection legislation, criteria and regulations that includes a self-contained evaluation system driven by the National Environmental Policy Act (NEPA) procedural guidelines (United States Council on Environmental Quality, 1978) and Environmental Impact Statement (EIS) requirements. The Corps of Engineers must use both the P&G and the NEPA/EIS system in discharging its responsibilities.If U.S. Federal agencies are to take the lead in formulating and evaluating adaptation options, there needs to be a reexamination of existing evaluation approaches. Among the elements of the P&G that may require rethinking in view of the prospects of global climate change are those relating to risk and uncertainty, nonstationarity, interest rates, and multiple objectives. Within the government planning process, efforts must be made to resolve inconsistencies and constraints in order to permit the optimal evaluation of water-based ecosystems under global climate change. The interrelationships of the two systems are described in this paper, and alternative ways of viewing the planning process are discussed. Strategic planning and management at the watershed level provides an effective approach to many of the issues. Current NEPA/EIS impact analysis does not provide a suitable framework for environmental impact analysis under climate uncertainty, and site-specific water resources evaluation relating to climate change appears difficult at current levels of knowledge about climate change. The IPCC Technical Guidelines, however, provide a useful beginning for assessing the impacts of future climate states.     

Voluntary relocation - An exploration of Australian attitudes in the context of drought, recycled and desalinated water

Throughout history settlements have been abandoned due to lack of water. Such a fate is of concern to public officials in settlements facing water scarcity - a condition which is anticipated to increase due to the impacts of climate change, and other factors including increasing per capita water use, and population growth. Key questions surround how to best adapt to these circumstances. A strategy little explored is relocation. This paper presents results from a qualitative study conducted in eight geographically diverse Australian locations. The willingness of individuals to relocate under three hypothetical water scenarios was investigated: (1) if the water in their community ran out, (2) if recycled wastewater was put in their community's drinking water supply, and (3) if desalinated water was put in their community's drinking water supply. Results indicate that most people would not relocate if recycled or desalinated water was used to augment their community's drinking water supply, but they would if their water supply ran out. Our results highlight that while there is initial public opposition to the augmentation of existing potable water supplies with recycled or desalinated water, people would prefer these solutions, over being forced to move location. Respondents were highly aware of the social, economic and public infrastructure costs associated with relocation decisions. Relocation would therefore, for most, only be the very last option if their water demands could not be met. However, it was difficult for most to imagine the situation becoming so dire. Our results highlight the importance of a comprehensive and consultative approach to managing supply in water scarce locations.