California coastal management with a changing climate

With over 2,000 miles (3,218 km) of ocean and estuarine coastline, California faces significant coastal management challenges as a result of climate change-induced sea level rise. Under high emission scenarios, recent models predict 1.4 m or more of sea level rise by 2100, accompanied by increasing storm surges. This article investigates the most important issues facing coastal managers, explores the policy tools available for adapting to the impacts of climate change, assesses institutional constraints to adaptation, and identifies priorities for future research and policy action. We find that adaptation tools exist for dealing with anticipated increases in coastal erosion and flooding, but they involve significant costs and tradeoffs. In particular, coastal armoring, such as seawalls, can protect developed coastal lands, but destroys beaches and habitat. Although California already has policies and institutions that aim to balance the competing objectives for coastal development, management agencies are at the early stages of understanding how to facilitate adaptation. Research priorities to inform coastal adaptation planning include: (i) inventorying coastal resources to provide a firmer basis for balancing decisions on property and habitat protection, (ii) identifying opportunities for coastal habitat migration, (iii) assessing the vulnerabilities of existing and planned coastal infrastructure, and (iv) experimenting with alternatives to armoring as a way of managing the changing coastline.     

Worst case scenario as stakeholder decision support: a 5- to 6-m sea level rise in the Rhone delta, France

Risk policy and public attitudes appear disconnected from research predicting warmer climate partially due to human activity. To step out of this stalled situation, a worst case scenario of a 5- to 6-m sea level rise (SLR) induced by the collapse of the WAIS and occurring during the period 2030–2130 is constructed and applied to the Rhone delta. Physical and socio-economic scenarios developed with data from the Rhone delta context are developed and submitted to stakeholders for a day-long workshop. Group process analysis shows a high level of trust and cooperation mobilized to face the 5–6 m SLR issue, despite potentially diverging interests. Two sets of recommendations stem from the scenario workshop. A conservative “wait and see” option is decided when the risk of the WAIS collapse is announced in 2030. After WAIS collapse generates an effective 1 m SLR rise by 2050, decisions are taken for total retreat and rendering of the Rhone delta to its hydrological function. The transposition of these results into present-day policy decisions could be considered. The methodology developed here could be applied to other risk objects and situations, and serve for policy exercises and crisis prevention.     

Spatial targeting of floodplain restoration to equitably mitigate flood risk

Floodplain restoration offers an opportunity to enhance communities’ resilience to flooding. However, the degree to which these interventions mitigate damages is often unknown, and identifying the best locations for implementation is a challenge. Further, the extent to which the benefits of flood mitigation are equitably distributed within communities is rarely considered in restoration projects. Here, we develop a novel framework to optimize investments in floodplain restoration that maximizes the utility of avoided damages from flood inundation for a range of budgetary constraints. We estimate the expected reduction in flood damages from restoration interventions by integrating a hydraulic flood model and an economic damage cost model. Using equity-weighted utility functions, we explicitly evaluate how the value of reduction in flood damages varies for different property owners. We demonstrate the potential of this approach in the Lewis Creek watershed, located in Vermont, USA. Under all optimal scenarios, the benefits of avoided flood damages over a 100-year time period outweigh the costs of restoration by at least 5-to-1. Floodplain restoration has the potential to reduce the present value of damages by up to $400,000, a 5% decrease from the baseline, at a cost of only $75,000. We also show that the equity-weighted utility of flood mitigation increase when restoration interventions protect the lowest-income property owners, particularly those who live in mobile homes. Together, our results illuminate the importance of evaluating the distribution of benefits and costs associated with alternative restoration strategies, as well as underscore the capacity for floodplain restoration to build resilience to flooding.     

Economic Implications of Potential ENSO Frequency and Strength Shifts

Some argue that global climate change may alter the frequency and strength of extreme events. This paper examines the economic damages in the agricultural sector arising from a shift in El Niño Southern Oscillation (ENSO) event frequency and strength. The assumptions about the frequency of ENSO shift are motivated by an article by Timmermann etal. (1999). The damage estimates reported here are in the context of the global agricultural system. Annual damages in the 3 to 4 hundred million U.S. dollar range are found if only the frequency of ENSO events changes. However, annual damages rise to over $1 billion if the events also intensify in strength. Event anticipation and crop mix adaption on the part of farmers can help offset the damages but cannot fully alleviate them.     

Risk mitigation and the social cost of carbon

The social cost of carbon – i.e., the marginal present-value cost imposed by greenhouse gas emissions – is determined by a complex interaction between factual assumptions, modeling methods, and value judgments. Among the most crucial factors is society's willingness to tolerate potentially catastrophic environmental risks. To explore this issue, the present analysis employs a stochastic climate–economy model that accounts for uncertainties in baseline economic growth, baseline emissions, greenhouse gas mitigation costs, carbon cycling, climate sensitivity, and climate change damages. In this model, preferences are specified to reflect the high degree of risk aversion revealed by private investment decisions, signaled by the large observed gap between the average rates of return paid by safe and risky financial instruments. In contrast, most climate–economy models assume much lower risk aversion. Given high risk aversion, the analysis finds that investment in climate stabilization yields especially large net benefits by forestalling low-probability threats to long-run human well-being. Accordingly, the social cost of carbon attains the markedly high value of $25,700 per metric ton of carbon dioxide in a baseline scenario in which emissions are unregulated. This value falls to just $4 per ton as the stringency of control measures is successively increased. These results cast doubt on the idea that the social cost of carbon takes on a uniquely defined, objective value that is independent of policy decisions. This does not, however, rule out the use of carbon prices to achieve the benefits of climate stabilization using least-cost mitigation measures.     

Effects of Climatic Change on a Water Dependent Regional Economy: A Study of the Texas Edwards Aquifer

Global climate change portends shifts in water demand and availability which may damage or cause intersectoral water reallocation in water short regions. This study investigates effects of climatic change on regional water demand and supply as well as the economy in the San Antonio Texas Edwards Aquifer region. This is done using a regional model which portrays both hydrological and economic activities. The overall results indicate that changes in climatic conditions reduce water resource availability and increase water demand. Specifically, a regional welfare loss of $2.2–$6.8million per year may occur as a result of climatic change. Additionally, if springflows are to be maintained at the currently desired level to protect endangered species, pumping must be reduced by 9–20% at an additional costof $0.5 to $2 million per year.     

A multi-level perspective on climate risks and drivers of entrepreneurial robustness – Findings from sectoral comparison in alpine Austria

Recent works on organizational adaptation to climate change have repeatedly stressed that – despite concerns about large-scale impacts of climate change on supply chain networks – studies on climate change adaptation in manufacturing industries are still surprisingly scarce. The following study develops a systemic analytical framework based on which climate risks for manufacturing industries are reviewed and drivers (defined as supportive factors) of entrepreneurial robustness are examined. The analysis builds upon a case study in the alpine Austrian state of Tyrol where an intense regional rise of average temperatures occurs, going along with increased risks of natural mountain hazards and exposed settlement structures. In this climate-sensitive setting the authors conducted a survey on risk perceptions among 102 managers from manufacturing firms. Based on a comparison of the sectors metal and engineering, timber products, and construction, the authors argue that drivers of entrepreneurial robustness can be subsumed under five major strategic principles: (a) the deployment of slack resources, (b) vertical supply chain integration, (c) manufacturing flexibility, (d) material efficiency, and (e) technological risk prevention. Departing from the empirical results, the authors argue that across these principles the development of drivers depends on an interplay of structural prerequisites and human decisions on the levels of the focal firm, the supply chain network, and the political, economic, and geographic environment. In this sense, the authors conceptualize different forms of contingencies – thus effects influencing the development of drivers – within an ontology which may support further system-oriented analysis of climate change adaptation in industry.     

Sea-Level Change: The Expected Economic Cost of Protection Or Abandonment in the United States

Three distinct models from earlier work are combined to: (1) produce probabilistically weighted scenarios of greenhouse-gas-induced sea-level rise; (2) support estimates of the expected discounted value of the cost of sea-level rise to the developed coastline of the United States, and (3) develop reduced-form estimates of the functional relationship between those costs to anticipated sea-level rise, the cost of protection, and the anticipated rate of property-value appreciation. Four alternative representations of future sulfate emissions, each tied consistently to the forces that drive the initial trajectories of the greenhouse gases, are considered. Sea-level rise has a nonlinear effect on expected cost in all cases, but the estimated sensitivity falls short of being quadratic. The mean estimate for the expected discounted cost across the United States is approximately $2 billion (with a 3% real discount rate), but the range of uncertainty around that estimate is enormous; indeed, the 10th and 90th percentile estimates run from less than $0.2 billion up to more than $4.6 billion. In addition, the mean estimate is very sensitive to associated sulfate emissions; it is, specifically, diminished by nearly 25% when base-case sulfate emission trajectories are considered and by more than 55% when high-sulfate trajectories are allowed.     

Fern species richness and abundance are indicators of climate change on high-elevation islands: evidence from an elevational gradient on Tahiti (French Polynesia)

Coastal sector impacts from sea level rise (SLR) are a key component of the projected economic damages of climate change, a major input to decision-making and design of climate policy. Moreover, the ultimate global costs to coastal resources will depend strongly on adaptation, society’s response to cope with the local impacts. This paper presents a new open-source optimization model to assess global coastal impacts from SLR from the perspective of economic efficiency. The Coastal Impact and Adaptation Model (CIAM) determines the optimal strategy for adaptation at the local level, evaluating over 12,000 coastal segments, as described in the DIVA database (Vafeidis et al. 2006), based on their socioeconomic characteristics and the potential impacts of relative sea level rise and uncertain sea level extremes. A deterministic application of CIAM demonstrates the model’s ability to assess local impacts and direct costs, choose the least-cost adaptation, and estimate global net damages for several climate scenarios that account for both global and local components of SLR (Kopp et al. 2014). CIAM finds that there is large potential for coastal adaptation to reduce the expected impacts of SLR compared to the alternative of no adaptation, lowering global net present costs through 2100 by a factor of seven to less than $1.7 trillion, although this does not include initial transition costs to overcome an under-adapted current state. In addition to producing aggregate estimates, CIAM results can also be interpreted at the local level, where retreat (e.g., relocate inland) is often a more cost-effective adaptation strategy than protect (e.g., construct physical defenses).     

A wedge-based approach to estimating health co-benefits of climate change mitigation activities in the United States

While it has been recognized that actions reducing greenhouse gas (GHG) emissions can have significant positive and negative impacts on human health through reductions in ambient fine particulate matter (PM_2.5) concentrations, these impacts are rarely taken into account when analyzing specific policies. This study presents a new framework for estimating the change in health outcomes resulting from implementation of specific carbon dioxide (CO₂) reduction activities, allowing comparison of different sectors and options for climate mitigation activities. Our estimates suggest that in the year 2020, the reductions in adverse health outcomes from lessened exposure to PM_2.5 would yield economic benefits in the range of $6 to $30 billion (in 2008 USD), depending on the specific activity. This equates to between $40 and $198 per metric ton of CO₂ in health benefits. Specific climate interventions will vary in the health co-benefits they provide as well as in potential harms that may result from their implementation. Rigorous assessment of these health impacts is essential for guiding policy decisions as efforts to reduce GHG emissions increase in scope and intensity.     

Storms, Investor Decisions, and the Economic Impacts of Sea Level Rise

Past research on the economic impacts of aclimate-induced sea level rise has been based on thegradual erosion of the shoreline, and humanadaptation. Erosion which is accelerated by sea levelrise may also increase the vulnerability to stormdamage by decreasing the distance between the shoreand structures, and by eroding protective coastalfeatures (dunes). We present methods of assessingthis storm damage in coastal regions where structuralprotection is not pursued. Starting from the boundingcases of no foresight and perfectforesight of Yohe et al. (1996), we use adisaggregated analysis which models the random natureof storms, and models market valuation and privateinvestor decisions dynamically. Using data from theNational Flood Insurance Program and a hypotheticalcommunity, we estimate that although the total stormdamage can be large, the increase in storm damageattributable to sea level rise is small (<5% oftotal sea level rise damages). These damages,however, could become more significant under otherreasonable assumptions or where dune erosion increasesstorm damage.     

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.     

A bridge too far? The influence of socio-cultural values on the adaptation responses of smallholders to a devastating pest outbreak in cocoa

The influence of socio-cultural factors on the adaptive capacity, resilience and trade-offs in decision-making of households and communities is receiving growing scholarly attention. In many partly transformed societies, where the market economy is not well developed, livelihood practices are heavily structured by kinship and indigenous social and economic values. Farm investment decisions and incentives to produce agricultural commodities are shaped by a host of considerations in addition to market imperatives like profit. In one such partly transformed society in East New Britain Province, Papua New Guinea, we examine the adaptation decisions of smallholders in response to the drastic drop of yield in their cocoa plots caused by the sudden outbreak of Cocoa Pod Borer. To explain why the impact of the pest has been so great we examine the interconnections between household responses, the local socio-cultural and economic context of smallholder commodity crop production and the wider institutional environment in which household choices and decisions are made. We argue that the significant lifestyle changes and labour intensive farming methods required for the effective control of Cocoa Pod Borer are incompatible with existing smallholder farming systems, values and livelihoods. To adopt a high input cropping system requires more than a technical fix and some training; it also requires abandoning a ‘way of life’ that provides status, identity and a moral order, and which is therefore highly resistant to change. The paper highlights the enduring influence and significance of local, culturally-specific beliefs and socio-economic values and their influence on how individuals and communities make adaptation decisions.     

Planning for Sea Level Rise and Shore Protection Under Climate Uncertainty

Attention is focused here on the effect of additional sources of uncertainty derived from climate change on the cost-benefit procedures applied by coastal planners to evaluate shoreline protection projects. The largest effect would be felt if planners were trying to achieve the first best economic optimum. Given the current view that the seas will rise by significantly less than one meter through the year 2100, present procedures should work reasonably well assuming (1) informed vigilance in monitoring the pace of future greenhouse induced sea level rise, (2) careful attention to the time required for market-based adaptation to minimize the economic cost of abandonment, and (3) firm support of the credibility of an announced policy to proceed with plans to retreat from the sea when warranted. Assumptions (1) and (2) might be satisfied in reality, even cursory review of existing policy makes it clear that meeting (3) is a "long shot" at the very best. In any case, planners should periodically revisit potential protection sites, especially in the wake of catastrophic events, to assess the impact of the most recent information on sea level rise trajectories, local development patterns, and protection costs on the decision calculus.     

The present and future role of coastal wetland vegetation in protecting shorelines: answering recent challenges to the paradigm

For more than a century, coastal wetlands have been recognized for their ability to stabilize shorelines and protect coastal communities. However, this paradigm has recently been called into question by small-scale experimental evidence. Here, we conduct a literature review and a small meta-analysis of wave attenuation data, and we find overwhelming evidence in support of established theory. Our review suggests that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves. In biophysical models, field tests, and natural experiments, the presence of wetlands reduces wave heights, property damage, and human deaths. Meta-analysis of wave attenuation by vegetated and unvegetated wetland sites highlights the critical role of vegetation in attenuating waves. Although we find coastal wetland vegetation to be an effective shoreline buffer, wetlands cannot protect shorelines in all locations or scenarios; indeed large-scale regional erosion, river meandering, and large tsunami waves and storm surges can overwhelm the attenuation effect of vegetation. However, due to a nonlinear relationship between wave attenuation and wetland size, even small wetlands afford substantial protection from waves. Combining man-made structures with wetlands in ways that mimic nature is likely to increase coastal protection. Oyster domes, for example, can be used in combination with natural wetlands to protect shorelines and restore critical fishery habitat. Finally, coastal wetland vegetation modifies shorelines in ways (e.g. peat accretion) that increase shoreline integrity over long timescales and thus provides a lasting coastal adaptation measure that can protect shorelines against accelerated sea level rise and more frequent storm inundation. We conclude that the shoreline protection paradigm still stands, but that gaps remain in our knowledge about the mechanistic and context-dependent aspects of shoreline protection.     

The poverty implications of climate-induced crop yield changes by 2030

Accumulating evidence suggests that agricultural production could be greatly affected by climate change, but there remains little quantitative understanding of how these agricultural impacts would affect economic livelihoods in poor countries. Here we consider three scenarios of agricultural impacts of climate change by 2030 (impacts resulting in low, medium, or high productivity) and evaluate the resulting changes in global commodity prices, national economic welfare, and the incidence of poverty in a set of 15 developing countries. Although the small price changes under the medium scenario are consistent with previous findings, we find the potential for much larger food price changes than reported in recent studies which have largely focused on the most likely outcomes. In our low-productivity scenario, prices for major staples rise 10–60% by 2030. The poverty impacts of these price changes depend as much on where impoverished households earn their income as on the agricultural impacts themselves, with poverty rates in some non-agricultural household groups rising by 20–50% in parts of Africa and Asia under these price changes, and falling by significant amounts for agriculture-specialized households elsewhere in Asia and Latin America. The potential for such large distributional effects within and across countries emphasizes the importance of looking beyond central case climate shocks and beyond a simple focus on yields – or highly aggregated poverty impacts.     

Learning about climate change and implications for near-term policy

Climate change is an issue of risk management. The most important causes for concern are not the median projections of future climate change, but the low-probability, high-consequence impacts. Because the policy question is one of sequential decision making under uncertainty, we need not decide today what to do in the future. We need only to decide what to do today, and future decisions can be revised as we learn more. In this study, we use a stochastic version of the DICE-99 model (Nordhaus WD, Boyer J (2000) Warming the world: economic models of global warming. MIT Press, Cambridge, MA, USA) to explore the effect of different rates of learning on the appropriate level of near-term policy. We show that the effect of learning depends strongly on whether one chooses efficiency (balancing costs and benefits) or cost-effectiveness (stabilizing at a given temperature change target) as the criterion for policy design. Then, we model endogenous learning by calculating posterior distributions of climate sensitivity from Bayesian updating, based on temperature changes that would be observed for a given true climate sensitivity and assumptions about errors, prior distributions, and the presence of additional uncertainties. We show that reducing uncertainty in climate uncertainty takes longer when there is also uncertainty in the rate of heat uptake by the ocean, unless additional observations are used, such as sea level rise.     

发达国家2020年前应对气候变化行动和支持力度盘点

在应对气候变化问题上,发达国家有率先减排和为发展中国家提供气候资金支持的义务。根据《联合国气候变化框架公约》相关成果,发达国家做出了到2020年减排温室气体和每年动员1000亿美元气候资金的承诺,综合相关数据信息盘点了上述承诺的实施进展,结果显示发达国家2020年减排目标力度不足,核算规则不清晰,部分国家缺乏减排进展,气候资金的概念和范围尚有争议,现有气候资金规模与承诺仍有较大差距,《联合国气候变化框架公约》下资金机制作用仍待加强,并且发展中国家需要更大规模的气候资金支持。发达国家2020年承诺兑现不力不利于巩固多边进程各方互信,且有向发展中国家转嫁责任之嫌。为此,建议中国在国际气候谈判进程中,依托谈判联盟,进一步敦促发达国家履行2020年承诺并提高力度。     

Regional patterns of U.S. household carbon emissions

Market-based policies to address fossil fuel-related externalities including climate change typically operate by raising the price of those fuels. Increases in energy prices have important consequences for a typical U.S. household that spent almost $4,000 per year on electricity, fuel oil, natural gas, and gasoline in 2005. A key question for policymakers is how these consequences vary over different regions and subpopulations across the country—especially as adjustment and compensation programs are designed to protect more vulnerable regions. To answer this question, we use non-publicly available data from the U.S. Consumer Expenditure Survey over the period 1984–2000 to estimate long-run geographic variation in household use of electricity, fuel oil, natural gas, and gasoline, as well as the associated incidence of a $10 per ton tax on carbon dioxide (ignoring behavioral response). We find substantial variation: incidence from the tax range from $97 dollars per year per household in New York County, New York to $235 per year per household in Tensas Parish, Louisiana. This variation can be explained by differences in energy use, carbon intensity of electricity generation, and electricity regulation.     

Insuring future climate catastrophes

The combined influences of a change in climate patterns and the increased concentration of property and economic activity in hazard-prone areas has the potential of restricting the availability and affordability of insurance. This paper evaluates the premiums that private insurers are likely to charge and their ability to cover residential losses against hurricane risk in Florida as a function of (a) recent projections on future hurricane activity in 2020 and 2040; (b) insurance market conditions (i.e., soft or hard market); (c) the availability of reinsurance; and (d) the adoption of adaptation measures (i.e., implementation of physical risk reduction measures to reduce wind damage to the structure and buildings). We find that uncertainties in climate projections translate into a divergent picture for insurance in Florida. Under dynamic climate models, the total price of insurance for Florida (assuming constant exposure) could increase significantly by 2040, from $12.9 billion (in 1990) to $14.2 billion, under hard market conditions. Under lower bound projections, premiums could decline to $9.4 billion by 2040. Taking a broader range of climate change scenarios, including several statistical ones, prices could be between $4.7 and $32.1 billion by 2040. The upper end of this range suggests that insurance could be unaffordable for many people in Florida. The adoption of most recent building codes for all residences in the state could reduce by nearly half the expected price of insurance so that even under high climate change scenarios, insurance premiums would be lower than under the 1990 baseline climate scenario. Under a full adaptation scenario, if insurers can obtain reinsurance, they will be able to cover 100 % of the loss if they allocated 10 % of their surplus to cover a 100-year return hurricane, and 63 % and 55 % of losses from a 250-year hurricane in 2020 and 2040. Property-level adaptation and the maintenance of strong and competitive reinsurance markets will thus be essential to maintain the affordability and availability of insurance in the new era of catastrophe risk.