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This study is a contribution to the ongoing debate about the selection of the approach for carbon accounting in wood products to be used, in the future, in the national greenhouse gas inventories under the UNFCCC (United Nations Framework Convention on Climate Change). Two accounting approaches are used in this analysis: the stock-change approach and the atmospheric-flow approach. They are applied to the Portuguese Eucalyptus globulus forest sector. To achieve this objective, the fluxes of wood removed from the forest are tracked through its life cycle, which includes products manufacture (mainly pulp and paper), use and final disposal (landfilling, incineration and composting). This study develops a framework to the estimation of carbon sequestration in the forest of E. globulus, a fast growing species, more specifically, in the calculation of the conversion factors such as bark and foliage percentages and densities, used to convert wood volumes into total biomass. A mass balance approach based on real data from mills is also proposed, in order to assess carbon emissions from wood processing. The results show that E. globulus forest sector was a carbon sink, but the magnitude of the carbon sequestration differs substantially depending on the accounting approach used. The contribution of the forest ecosystem was smaller than the aggregated contribution of wood products in use and in landfills (including industrial waste), which reinforces the role that wood products play in national carbon budgets. [ABSTRACT FROM AUTHOR]

Using an experimental auction, we explore how verifiable information affects the willingness to pay (WTP) for two climate friendly goods given the politicized climate change debate. We test whether the dissemination of (scientific) verifiable information lets subjects cut through the media noise. We define our baseline by first examining how noisy information (pro and con) about climate change affects WTP. We then consider how third party verifiable information within this noisy information affects WTP. Our results suggest subjects could cut through noisy information to process verifiable information. We find a significant WTP premium for climate protection. The verifiable information treatment increases the premium for both shade-grown coffee (by 51 %) and recycled paper (by 48 %). This suggests the WTP premium for climate change depends on the available information flow and the characteristics of the climate friendly good. [ABSTRACT FROM AUTHOR]

In this paper, a systematic literature review was conducted to synthesize understanding on farmers' perception on climate change. Farmers' perception of climate change is conceptualized as comprising of three dimensions—first, as farmers' "awareness"; second, "conceptual understanding"; and third, the "experience" of climate change. The review included 162 papers published during the period January 2000 to July 2019. The highest number of studies was conducted in Africa, followed by Asia. A large majority of farmers report being aware of climate change. However, only a few studies elicit the difference between climate variability and climate change from farmers. A negligible number of studies attempt to identify the role of agricultural activities in greenhouse gas emissions and climate change. Furthermore, authors compare farmers' perception with meteorological evidence, which is more aligned in terms of change in "temperature" rather than "precipitation." The insights from the review provide guidance on conceptualization and operationalization of the variable "farmers' perception of climate change" for future studies. [ABSTRACT FROM AUTHOR]

The widespread demand for animal-sourced foods poses challenges in addressing climate change due to their significant greenhouse gas emissions. Alternative proteins like cultured meat show promise with lower greenhouse gas emissions, but have faced public resistance, posing substantial barriers to their broad development and adoption. This paper reports a survey that examined the perceived naturalness of protein sources as an important factor that predicts perceived risks, benefits, and support for consumption. A diverse sample from the United States considered six different protein technologies, including three newer alternative proteins such as cultured meat and three more conventional proteins. Newer alternative proteins were perceived as less natural and were less supported than conventional proteins. Additionally, the more participants perceived protein sources as natural, the less risky and more beneficial they perceived them to be, contributing to their support. These results suggest that perceived naturalness, and associated risks and benefits, could be an important factor in shaping public support for or opposition to new proteins. These findings have theoretical and broader implications for the development and adoption of sustainability technologies. [ABSTRACT FROM AUTHOR]

Over the last few years, California has passed some of the strongest climate policies in the USA. These new policies have been motivated in part by increasing concerns over the risk of climate-related impacts and facilitated by the state's existing framework of energy and air quality policies. This paper presents an overview of the evolution of this increased awareness of climate change issues by policy makers brought about by the strong link between climate science and policy in the state. The State Legislature initiated this link in 1988 with the mandate to prepare an assessment of the potential consequences of climate change to California. Further interactions between science and policy has more recently resulted, in summer of 2006, in the passage of Assembly Bill 32, a law that limits future greenhouse gas emissions in California. This paper discusses the important role played by a series of state and regional climate assessments beginning in 1988 and, in particular, the lessons learned from a recently completed study known as the Scenarios Project. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper provides an assessment of Article 4.1 of the Paris Agreement on climate; the main goal of which is to provide guidance on how “to achieve the long-term temperature goal set out in Article 2”. Paraphrasing, Article 4.1 says that, to achieve this end, we should decrease greenhouse gas (GHG) emissions so that net anthropogenic GHG emissions fall to zero in the second half of this century. To aggregate net GHG emissions, 100-year global warming potentials (GWP-100) are commonly used to convert non-CO2 emissions to equivalent CO2 emissions. The GWP-scaling method is tested using methane as an example. The temperature projections using GWP-100 scaling are shown to be seriously in error. This throws doubt on the use of GWP-100 scaling to estimate net GHG emissions. An alternative method to determine the net-zero point for GHG emissions based on radiative forcing is derived, where the net-zero point is identified with the maximum of GHG forcing. This shows that, to meet the Article 2 warming goal, the net-zero point for GHG emissions needs to be reached as early as 2036, much sooner than in the Article 4.1 window. Other scientific problems in Article 4.1 that further undermine its purpose to guide efforts to achieve the Article 2 temperature targets are discussed. [ABSTRACT FROM AUTHOR]

How do we understand national climate change politics in the United States? Using a methodological innovation in network analysis, this paper analyzes discussions about the issue within the US Congress. Through this analysis, the ideological relationships among speakers providing Congressional testimony on the issue of climate change are mapped. For the first time, issue stances of actors are systematically aggregated in order to measure coalitions and consensus among political actors in American climate politics in a relational way. Our findings show how consensus formed around the economic implications of regulating greenhouse gases and the policy instrument that should do the regulating. The paper is separated into three sections. First, we review the ways scholars have looked at climate change policymaking in the United States, paying particular attention to those who have looked at the issue within the US Congress. Next, we present analysis of statements made during Congressional hearings on climate change over a four-year period. Our analysis demonstrates how a polarized ideological actor space in the 109 Congress transforms into a more consensual actor landscape in the 110 Congress, which is significantly less guided by partisan differences. This paper concludes by discussing how these findings help us understand shifting positions within American climate politics and the implications of these findings. [ABSTRACT FROM AUTHOR]

This paper provides an economic perspective of adaptation to climate change. The paper specifically examines the role of markets and government in efficient adaptation responses. For adaptations to be efficient, the benefits from following adaptations must exceed the costs. For private market goods, market actors will follow this principle in their own interest. For public goods, governments must take on this responsibility. Governments must also be careful to design institutions that encourage efficiency or they could inadvertently increase the damages from climate change. Finally, although in a few cases actors must anticipate climate changes far into the future, generally it is best to learn and then act with respect to adaptation. [ABSTRACT FROM AUTHOR]

Climate change can be difficult for laypeople to make sense of, because of its complexity, the uncertainties involved and its distant impacts. Research has identified the potentials of Information and Communication Technologies (ICT) for visualizing and communicating climate change to lay audiences and thus addressing these communication challenges. However, little research has focused on how ICT-based visualization affects audiences' understandings of climate change. Employing a semiotic framework and through a combination of focus group interviews and mindmap exercises, we investigated how Swedish students make sense of climate messages presented through an ICT-based visualisation medium; a dome theatre movie. The paper concludes that visualization in immersive environments works well to concretize aspects of climate change and provide a starting point for reflection, but we argue that the potential to add interactive elements should be further explored, as interaction has the potential to influence meaning-making processes. In addition, audiences' preconceptions of climate change influence their interpretations of climate messages, which may function as a constraint to climate communication. [ABSTRACT FROM AUTHOR]

The Paris pledges are unique documents in climate governance that outline what each country intends to do to combat climate change. Often, these documents contain headline greenhouse gas percentage reduction targets that appear to summarize countries' contributions to mitigation. This is a boon for comparative climate policy research. However, I show in this paper that the Paris pledges require detailed interpretation to be comparable. I demonstrate the risks in comparing these targets by re-visiting a recent studying linking national public opinion to the stringency of countries' mitigation goals. I develop new indicators that better account for the structure of the targets and show in replications that the original finding is inconsistent with the underlying data. I conclude by drawing lessons for studying the Paris pledges. [ABSTRACT FROM AUTHOR]

We analyze a mini ensemble of regional climate projections over the CORDEX Africa domain carried out with RegCM4 model as part of the Phase I CREMA experiment (Giorgi ). RegCM4 is driven by the HadGEM2-ES and MPI-ESM global models for the RCP8.5 and RCP4.5 greenhouse gas and aerosol concentration scenarios. The focus of the analysis is on seasonal and intraseasonal monsoon characteristics. We find two prominent change signals. Over West Africa and the Sahel MPI produces a forward shift in the monsoon season in line with previous findings, and this shift is also simulated by the RegCM4. Furthermore, the regional model produces a widespread decrease of monsoon precipitation (when driven by both MPI and HadGEM) associated with decreased easterly wave activity in the 6-9 days regime and with soil moisture-precipitation interactions. South of the equator we find an extension of the dry season with delayed onset and anticipated recession of the monsoon and a narrowing and strengthening of the ITCZ precipitation band. This signal is consistent in all global and regional model projections, although with different spatial detail. We plan to enlarge this mini-ensemble as a further contribution to the CORDEX project to better assess the robustness of the signals found in this paper. [ABSTRACT FROM AUTHOR]

This paper offers insights for assessing organizational resilience to the effects of climate change, specifically to climate and weather extremes. The assessment of organizational resilience to climate and weather extremes brings about several challenges due to (1) uncertainties about future climate change outcomes across temporal and spatial scales and (2) a lack of insight into what lead to organizational resilience, or which variables should be measured in a given study. We suggest methodological pathways for organizational managers to identify properties of future climate and weather extremes and to include them in resilience assessments. We also suggest approaches to identify factors that promote organizational resilience to selected climate and weather extremes. Findings are intended to help managers to understand how organizational resilience to climate and weather extremes can be enhanced. [ABSTRACT FROM AUTHOR]

Exploiting surface albedo change has been proposed as a form of geoengineering to reduce the heating effect of anthropogenic increases in greenhouse gases (GHGs). Recent modeling experiments have projected significant negative radiative forcing from large-scale implementation of albedo reduction technologies ('cool' roofs and pavements). This paper complements such model studies with measurement-based calculations of the direct radiation balance impacts of replacement of conventional roofing with 'cool' roof materials in California. This analysis uses, as a case study, the required changes to commercial buildings embodied in California's building energy efficiency regulations, representing a total of 4300 ha of roof area distributed over 16 climate zones. The estimated statewide mean radiative forcing per 0.01 increase in albedo (here labeled RF01) is −1.38 W/m. The resulting unit-roof-area mean annual radiative forcing impact of this regulation is −44.2 W/m. This forcing is computed to counteract the positive radiative forcing of ambient atmospheric CO at a rate of about 41 kg for each square meter of roof. Aggregated over the 4300 ha of cool roof estimated built in the first decade after adoption of the State regulation, this is comparable to removing about 1.76 million metric tons (MMT) of CO from the atmosphere. The point radiation data used in this study also provide perspective on the spatial variability of cool roof radiative forcing in California, with individual climate zone effectiveness ranging from −37 to −59 W/m of roof. These 'bottom-up' calculations validate the estimates reported for published 'top down' modeling, highlight the large spatial diversity of the effects of albedo change within even a limited geographical area, and offer a potential methodology for regulatory agencies to account for the climate effects of 'cool' roofing in addition to its well-known energy efficiency benefits. [ABSTRACT FROM AUTHOR]

This paper describes research to estimate the effects of climate change on two high-elevation hydropower systems in California: the Upper American River Project, operated by the Sacramento Municipal Utility District, and the Big Creek system, operated by Southern California Edison. The study builds on a previous model of the Upper American River Project, which is here modified and extended for use to simulate two hydropower systems under various conditions. Future operations of the two high-elevation systems are simulated using climate change scenarios provided for the Second California Assessment. These scenarios suggest reduced precipitation and reduced runoff for both systems, and a shift toward runoff earlier in the year. The change in the hydrograph is somewhat greater for the Upper American River Project system, because its basins lie at a lower elevation. Reduced runoff directly reduces energy generation and revenues from both systems. Because the Upper American River Project system is projected to have greater spills with warmer climate conditions, it also has greater reduction in energy generation and revenues. Both systems continue to meet peak historical power demands in summer under most climate projections. However, if the number of heat waves increases in the late summer (September), reservoir operating strategies may need to be modified. [ABSTRACT FROM AUTHOR]

wide variety of scenarios for future development have played significant roles in climate policy discussions. This paper presents projections of greenhouse gas (GHG) concentrations, sea level rise due to thermal expansion and glacial melt, oceanic acidity, and global mean temperature increases computed with the MIT Integrated Global Systems Model (IGSM) using scenarios for twenty-first century emissions developed by three different groups: intergovernmental (represented by the Intergovernmental Panel on Climate Change), government (represented by the U.S. government Climate Change Science Program) and industry (represented by Royal Dutch Shell plc). In all these scenarios the climate system undergoes substantial changes. By 2100, the CO concentration ranges from 470 to 1020 ppm compared to a 2000 level of 365 ppm, the CO-equivalent concentration of all greenhouse gases ranges from 550 to 1780 ppm in comparison to a 2000 level of 415 ppm, oceanic acidity changes from a current pH of around 8 to a range from 7.63 to 7.91, in comparison to a pH change from a preindustrial level by 0.1 unit. The global mean temperature increases by 1.8 to 7.0°C relative to 2000. Such increases will require considerable adaptation of many human systems and will leave some aspects of the earth's environment irreversibly changed. Thus, the remarkable aspect of these different approaches to scenario development is not the differences in detail and philosophy but rather the similar picture they paint of a world at risk from climate change even if there is substantial effort to reduce emissions. [ABSTRACT FROM AUTHOR]

A collapse of the West-Antarctic Ice Sheet (WAIS) would cause a sea level rise of 5–6 m, perhaps even within 100 years, with catastrophic consequences. The probability of such a collapse is small but increasing with the rise of the atmospheric concentrations of greenhouse gas and the resulting climate change. This paper investigates how the potential collapse of the WAIS affects the optimal rate of greenhouse gas emission control. We design a decision and learning tree in which decision are made about emission reduction at regular intervals: the decision makers (who act as social planners) have to decide whether to implement the environmental or not (keeping then the flexibility to act later). By investing in the environmental policy, they determine optimally the date of the optimal emission reduction. At the same time, they receive new information on the probability of a WAIS collapse and the severity of its impacts. The probability of a WAIS collapse is endogenous and contingent on greenhouse gas concentrations. We solve this optimisation problem by backward induction. We find that a potential WAIS collapse substantially bring the date of the optimal emission reduction forward and increases its amount if the probability is high enough (a probability of 1% per year for the worst case), if the impacts are high enough (a worst case damage of 10% of GDP for a 3˚C warming) or if the decision maker is risk averse enough (for example a social damage due to pollution equal to 1% GDP for an atmospheric temperature of 3˚C). We also find that, as soon as a WAIS collapse is a foregone fact, emission reduction falls to free up resource to prepare for adapting to the inevitable. By contrast, adaptation (such as building dikes along the coast) postpones policy intervention because that strategy reduces the risk of catastrophic damages. [ABSTRACT FROM AUTHOR]

Abstract During the negotiations on the Kyoto Protocol, Brazil proposed allocating the greenhouse gas emission reductions of Annex I Parties according to the relative effect of a country’s historical emissions on global temperature increase. This paper analyses the impact of scientific uncertainties and of different options in policy implementation (policy choices) on the contribution of countries’ historical emissions to indicators of historical responsibility for climate change. The influence of policy choices was found to be at least as large as the impact of the scientific uncertainties analysed here. Building on this, the paper then proceeds to explore the implications of applying the Brazilian Proposal as a climate regime for differentiation of future commitments on the global scale combined with an income threshold for participation of the non-Annex I regions. Under stringent climate targets, such a regime leads to high emission reductions for Annex I regions by 2050, in particular for Europe and Japan. The income threshold assumptions strongly affect the Annex I reductions, even more than the impact of another burden-sharing key. A variant of the Brazilian Proposal, allocating emission reductions on the basis of cumulative emissions since 1990, would lead to a more balanced distribution of emission reductions. [ABSTRACT FROM AUTHOR]

Abstract As carbon dioxide and other greenhouse gasses accumulate in the atmosphere and contribute to rising global temperatures, it is important to examine how a changing climate may affect natural and managed ecosystems. In this series of papers, we study the impacts of climate change on agriculture, water resources and natural ecosystems in the General Circulation Model (GCM)-derived climate change projections, described in Part 1, to drive the crop production and water resource models EPIC (Erosion Productivity Impact Calculator) and HUMUS (Hydrologic Unit Model of the United States). These models are described and validated in this paper using historical crop yields and streamflow data in the conterminous United States in order to establish their ability to accurately simulate historical crop and water conditions and their capability to simulate crop and water response to the extreme climate conditions predicted by GCMs. EPIC simulated grain and forage crop yields are compared with historical crop yields from the US Department of Agriculture (USDA) and with yields from agricultural experiments. EPIC crop yields correspond more closely with USDA historical county yields than with the higher yields from intensively managed agricultural experiments. The HUMUS model was validated by comparing the simulated water yield from each hydrologic basin with estimates of natural streamflow made by the US Geological Survey. This comparison shows that the model is able to reproduce significant observed relationships and capture major trends in water resources timing and distribution across the country. [ABSTRACT FROM AUTHOR]

This paper discusses relationships between soil conservation, carbon sequestration, and the Kyoto Protocol. The Kyoto Protocol is the first attempt to use the flexibility of the global market place to stabilize and reduce GHG emissions, mitigate climate change, and promote sustainable development. The protocol emerged first as a framework agreement, but through international negotiations it is progressing into sets of legal articles. These impose obligations on all signatories, but they also identify opportunities for improved environmental land management at local, national and international levels. This is particularly true for soil conservation, where the sequestration of carbon above and below ground increases soil organic matter, enhances soil fertility, and improves production, while concomitantly reducing atmospheric CO2. It is a classic `win-win' situation. Both the evolving opportunities and the obligations under the Kyoto Protocol are discussed in the paper. [ABSTRACT FROM AUTHOR]

This paper proposes the creation of a club of carbon markets (CCM), to promote deep reductions in greenhouse gas emissions by supporting the development, harmonization, and increased ambition of domestic carbon markets. To achieve its aims, the club would establish common or reciprocal standards for environmental market infrastructure, transparency and environmental integrity; offer mutual recognition of members' emissions units; allow participating jurisdictions to share experience and gain assistance in building institutional capacity; and promote domestic and cross-border investment in low-carbon development. Using a suite of incentives, including some from the trade arena, a club of carbon markets could serve as a powerful attractive nucleus for broadening the participation of jurisdictions in climate mitigation, much as the General Agreement on Tariffs and Trade (GATT) served as the nucleus for broadening trade in products and services. A carbon markets club could be launched under UNFCCC auspices, but a more promising avenue might be to pursue the creation of the CCM as a complement to but outside the UN talks. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to describe global urban greenhouse gas emissions by region and sector, examine the distribution of emissions through the urban-to-rural gradient, and identify covariates of emission levels for our baseline year, 2000. We use multiple existing spatial databases to identify urban extent, greenhouse gas emissions (CO 2, N 2O, CH 4 and SF 6) and covariates of emissions in a “top-down” analysis. The results indicate that urban activities are significant sources of total greenhouse gas emissions (36.8 and 48.6 % of total). The urban energy sector accounts for between 41.5 and 66.3 % of total energy emissions. Significant differences exist in the urban share of greenhouse gas emissions between developed and developing countries as well as among source sectors for geographic regions. The 50 largest urban emitting areas account for 38.8 % of all urban greenhouse gas emissions. We find that greenhouse gas emissions are significantly associated with population size, density, growth rates, and per capita income. Finally, comparison of our results to “bottom-up” estimates suggest that this research’s data and techniques are best used at the regional and global scales. [ABSTRACT FROM AUTHOR]

A favoured method of assimilating information from state-of-the-art climate models into integrated assessment models of climate impacts is to use the transient climate response (TCR) of the climate models as an input, sometimes accompanied by a pattern matching approach to provide spatial information. More recent approaches to the problem use TCR with another independent piece of climate model output: the land-sea surface warming ratio ( φ). In this paper we show why the use of φ in addition to TCR has such utility. Multiple linear regressions of surface temperature change onto TCR and φ in 22 climate models from the CMIP3 multi-model database show that the inclusion of φ explains a much greater fraction of the inter-model variance than using TCR alone. The improvement is particularly pronounced in North America and Eurasia in the boreal summer season, and in the Amazon all year round. The use of φ as the second metric is beneficial for three reasons: firstly it is uncorrelated with TCR in state-of-the-art climate models and can therefore be considered as an independent metric; secondly, because of its projected time-invariance, the magnitude of φ is better constrained than TCR in the immediate future; thirdly, the use of two variables is much simpler than approaches such as pattern scaling from climate models. Finally we show how using the latest estimates of φ from climate models with a mean value of 1.6-as opposed to previously reported values of 1.4-can significantly increase the mean time-integrated discounted damage projections in a state-of-the-art integrated assessment model by about 15 %. When compared to damages calculated without the inclusion of the land-sea warming ratio, this figure rises to 65 %, equivalent to almost 200 trillion dollars over 200 years. [ABSTRACT FROM AUTHOR]

The economics of CO2 capture and storage in relation to the possibility of leakage of CO2 from geological reservoirs once this greenhouse gas has been stored artificially underground will be among the main determinants of whether CCS can significantly contribute to a deep cut in global CO2 emissions. This paper presents an analysis of the economic and climatic implications of the large-scale use of CCS for reaching a stringent climate change control target, when geological CO2 leakage is accounted for. The natural scientific uncertainties regarding the rates of possible leakage of CO2 from geological reservoirs are likely to remain large for a long time to come. We present a qualitative description, a concise analytical inspection, as well as a more detailed integrated assessment model, proffering insight into the economics of geological CO2 storage and leakage. Our model represents three main CO2 emission reduction options: energy savings, a carbon to non-carbon energy transition and the use of CCS. We find CCS to remain a valuable option even with CO2 leakage of a few percent per year, well above the maximum seepage rates that we think are likely from a geo-scientific point of view. [ABSTRACT FROM AUTHOR]

Sea-level rise (SLR) due to climate change is a serious global threat: The scientific evidence is now overwhelming. Continued growth of greenhouse gas emissions and associated global warming could well promote SLR of 1 m in this century, and unexpectedly rapid breakup of the Greenland and West Antarctic ice sheets might produce a 3–5 m SLR. In this paper, we assess the consequences of continued SLR for 84 coastal developing countries. Geographic Information System (GIS) software has been used to overlay the best available, spatially disaggregated global data on critical impact elements (land, population, agriculture, urban extent, wetlands, and GDP), with the inundation zones projected for 1–5 m SLR. Our results reveal that tens of millions of people in the developing world are likely to be displaced by SLR within this century; and accompanying economic and ecological damage will be severe for many. At the country level results are extremely skewed, with severe impacts limited to a relatively small number of countries. [ABSTRACT FROM AUTHOR]

This paper investigates the uncertainty in the impact of climate change on flood frequency in England, through the use of continuous simulation of river flows. Six different sources of uncertainty are discussed: future greenhouse gas emissions; Global Climate Model (GCM) structure; downscaling from GCMs (including Regional Climate Model structure); hydrological model structure; hydrological model parameters and the internal variability of the climate system (sampled by applying different GCM initial conditions). These sources of uncertainty are demonstrated (separately) for two example catchments in England, by propagation through to flood frequency impact. The results suggest that uncertainty from GCM structure is by far the largest source of uncertainty. However, this is due to the extremely large increases in winter rainfall predicted by one of the five GCMs used. Other sources of uncertainty become more significant if the results from this GCM are omitted, although uncertainty from sources relating to modelling of the future climate is generally still larger than that relating to emissions or hydrological modelling. It is also shown that understanding current and future natural variability is critical in assessing the importance of climate change impacts on hydrology. [ABSTRACT FROM AUTHOR]

The economic benefits of a multi-gas approach to climate change mitigation are clear. However, there is still a debate on how to make the trade-off between different greenhouse gases (GHGs). The trade-off debate has mainly centered on the use of Global Warming Potentials (GWPs), governing the trade-off under the Kyoto Protocol, with results showing that the cost-effective valuation of short-lived GHGs, like methane (CH4), should be lower than its current GWP value if the ultimate aim is to stabilize the anthropogenic temperature change. However, contrary to this, there have also been proposals that early mitigation mainly should be targeted on short-lived GHGs. In this paper we analyze the cost-effective trade-off between a short-lived GHG, CH4, and a long-lived GHG, carbon dioxide (CO2), when a temperature target is to be met, taking into consideration the current uncertainty of the climate sensitivity as well as the likelihood that this will be reduced in the future. The analysis is carried out using an integrated climate and economic model (MiMiC) and the results from this model are explored and explained using a simplified analytical economic model. The main finding is that the introduction of uncertainty and learning about the climate sensitivity increases the near-term cost-effective valuation of CH4 relative to CO2. The larger the uncertainty span, the higher the valuation of the shortlived gas. For an uncertainty span of ±1°C around an expected climate sensitivity of 3°C, CH4 is cost-effectively valued 6.8 times as high as CO2 in year 2005. This is almost twice as high as the valuation in a deterministic case, but still significantly lower than its GWP100 value. [ABSTRACT FROM AUTHOR]

In addition to reducing greenhouse gas emissions, actions to achieve a sustainable coexistence with wildfire need to be taken now. In this paper we suggest several important policy, planning, and management changes that should be made, regardless of the many uncertainties in predicting future fire regimes. Similar to how other natural hazards are addressed, a risk-based framework for fire-related decisions is crucial. Reintroduction of fire to fire-prone ecosystems, careful use of fire surrogates, and creation of new and flexible policies will be needed for successful ecosystem management. Growing incompatibilities between urban development and wildfire also require a serious reevaluation of urban planning and building in fire-prone locations to reach a sustainable coexistence with fire. Our future cities and communities must be less susceptible to wildfire damage, and the ecosystems upon which we depend must be made more resilient to further disruptions in fire regimes. [ABSTRACT FROM AUTHOR]

There is growing evidence that, as a result of global climate change, some of the most severe weather events could become more frequent in Europe over the next 50 to 100 years. The paper aims to (i) describe observed trends and scenarios for summer heat waves, windstorms and heavy precipitation, based on results from simulations with global circulation models, regional climate models, and other downscaling procedures, and (ii) discuss potential impacts on agricultural systems and forests in Switzerland. Trends and scenarios project more frequent heavy precipitation during winter corresponding, for example, to a three-fold increase in the exceedance of today's 15-year extreme values by the end of the 21st century. This increases the risk of large-scale flooding and loss of topsoil due to erosion. In contrast, constraints in agricultural practice due to waterlogged soils may become less in a warmer climate. In summer, the most remarkable trend is a decrease in the frequency of wet days, and shorter return times of heat waves and droughts. This increases the risk of losses of crop yield and forage quality. In forests, the more frequent occurrence of dry years may accelerate the replacement of sensitive tree species and reduce carbon stocks, and the projected slight increase in the frequency of extreme storms by the end of the century could increase the risk of windthrow. Some possible measures to maintain goods and services of agricultural and forest ecosystems are mentioned, but it is suggested that more frequent extremes may have more severe consequences than progressive changes in means. In order to effectively decrease the risk for social and economic impacts, long-term adaptive strategies in agriculture and silviculture, investments for prevention, and new insurance concepts seem necessary. [ABSTRACT FROM AUTHOR]

This paper examines different concepts of a 'warming commitment' which is often used in various ways to describe or imply that a certain level of warming is irrevocably committed to over time frames such as the next 50 to 100 years, or longer. We review and quantify four different concepts, namely (1) a 'constant emission warming commitment', (2) a 'present forcing warming commitment', (3) a 'zero emission (geophysical) warming commitment' and (4) a 'feasible scenario warming commitment'. While a 'feasible scenario warming commitment' is probably the most relevant one for policy making, it depends centrally on key assumptions as to the technical, economic and political feasibility of future greenhouse gas emission reductions. This issue is of direct policy relevance when one considers that the 2002 global mean temperatures were 0.8 ± 0.2°C above the pre-industrial (1861-1890) mean and the European Union has a stated goal of limiting warming to 2°C above the pre-industrial mean: What is the risk that we are committed to overshoot 2°C? Using a simple climate model (MAGICC) for probabilistic computations based on the conventional IPCC uncertainty range for climate sensitivity (1.5 to 4.5 °C), we found that (1) a constant emission scenario is virtually certain to overshoot 2°C with a central estimate of 2.0°C by 2100 (4.2°C by 2400). (2) For the present radiative forcing levels it seems unlikely that 2°C are overshoot. (central warming estimate 1.1 °C by 2100 and 1.2°C by 2400 with ∼10% probability of overshooting 2°C). However, the risk of overshooting is increasing rapidly if radiative forcing is stabilized much above 400 ppm CO2 equivalence (1.95 W/m²) in the long-term. (3) From a geophysical point of view, if all human-induced emissions were ceased tomorrow, it seems 'exceptionally unlikely' that 2°C will be overshoot (central estimate: 0.7°C by 2100; 0.4°C by 2400). (4) Assuming future emissions according to the lower end of published mitigation scenarios (350 ppm CO2eq to 450 ppm CO2eq) provides the central temperature projections are 1.5 to 2.1 °C by 2100 (1.5 to 2.0°C by 2400) with a risk of overshooting 2°C between 10 and 50% by 2100 and 1-32% in equilibrium. Furthermore, we quantify the 'avoidable warming' to be 0.16-0.26°C for every 100 GtC of avoided CO2 emissions - based on a range of published mitigation scenarios. [ABSTRACT FROM AUTHOR]

The greenhouse gas emissions scenarios published by the IPCC in the Special Report on Emission Scenarios (SRES) continue to serve as a primary basis for assessing future climate change and possible response strategies. These scenarios were developed between 1996 and 1999 and sufficient time has now passed to make it worth examining their consistency with more recent data and projections. The comparison performed in this paper includes population, GDP, energy use, and emissions of CO2, non-CO2 gases and sulfur. We find the SRES scenarios to be largely consistent with historical data for the 1990-2000 period and with recent projections. Exceptions to this general observation include (1) in the long-term, relatively high population growth assumptions in some regions, particularly in the A2 scenario; (2) in the medium-term, relatively high economic growth assumptions in the LAM (Latin America, Africa and Middle East) region in the A1 scenario; (3) in the short-term, CO2 emissions projections in Al that are somewhat higher than the range of current scenarios; and (4) substantially higher sulfur emissions in some scenarios than in historical data and recent projections. In conclusion, given the relatively small inconsistencies for use as global scenarios there seems to be no immediate need for a large-scale IPCC-led update of the SRES scenarios that is solely based on the SRES scenario performance vis-a-vis data for the 1990-2000 period and/or more recent projections. Based on reported findings, individual research teams could make, and in some cases already have made, useful updates of the scenarios. [ABSTRACT FROM AUTHOR]

Long-living wood products contribute to the mitigation of climate change in many ways. They act as a carbon pool during their service life, as they withdraw CO2 from its natural cycle. After their service life, they can substitute for fossil fuels if they are incinerated in adequate furnaces. Furthermore, wood products can substitute for more energy-intense products made of 'conventional' materials. This paper quantifies the substitution and pool effects of an increased use of wood in the building sector in Switzerland for the years 2000-2130. Life cycle data on greenhouse gas (GHG) emissions of 12 wood products and their substitutes are used as proxies for relevant building products; this data is linked to the forecasted wood flows for each group of building products in a cohort-model. For the political assessment, GHG effects occurring abroad and in Switzerland are distinguished. The results show that the pool effect of an increased use of long-living wood products is of minor importance, whereas the energetic and material substitution effects are much more relevant, especially on a long-term. For construction products, the Swiss share of the GHG effect related to the material substitution is relatively high, as mainly nationally produced materials are substituted for. For interior products, the Swiss share of the GHG effect related to the material substitution is rather small because mainly imports are substituted for. The results must be considered as rough estimates. Nonetheless, these calculations show that an increased use of wood in the building sector is a valid and valuable option for the mitigation of greenhouse gas emissions and for reaching GHG emission targets in a mid- to long-term. Still, the pool and substitution capacity of an increased use of wood is relatively small compared to the overall GHG emissions of Switzerland. [ABSTRACT FROM AUTHOR]

Grasslands are important carbon sinks, but the underlying processes for their soil carbon sequestration potential are still not well understood, despite much attention given to this topic. In Europe, grasslands, especially semi-natural grasslands, are also important for promoting biodiversity. Moreover, recent global reports have highlighted the importance of biodiversity in supporting climate actions. In boreal and alpine regions in the Nordic countries, grasslands also play an important role in milk and meat production and food security. Certain grassland features and management practices may enhance their soil carbon sequestration potential. Semi-natural grasslands maintained by optimized livestock grazing are vital for aboveground biodiversity and show promise for belowground biodiversity and carbon sequestration potential. It is essential to assess the multiple functions of grasslands, particularly semi-natural grasslands, to facilitate the optimization of policy measures across policy areas. Climate and biodiversity policies should not counteract each other, as some do today. This essay addresses the multiple functions of grasslands and calls for more knowledge about carbon sequestration in Nordic grasslands. This will enable the management of these ecosystems to align with climate mitigation, maintain biodiversity, and satisfy the global need for increased food supply. [ABSTRACT FROM AUTHOR]

Adaptation and mitigation are complementary strategies for addressing the impacts of climate change, yet are often considered separately. This paper examines the literature for evidence of the interactions of adaptation and mitigation measures across the agriculture, biodiversity, coasts, forests, urban and water sectors, focusing on Europe. It found that often adaptation and mitigation synergies and conflicts were not explicitly mentioned within a sector, let alone between sectors. Most measures, however, were found to have an effect on another sector, resulting in neutral, positive (synergies) or negative (conflicts) interactions within and between sectors. Many positive cross-sectoral interactions involved biodiversity or water and thus these could represent good starting places for the implementation of integrated, cross-sectoral strategies. Previous studies suggest that adaptation and mitigation are undertaken on different time and geographical scales; this study found many local scale measures which could facilitate integration between both adaptation and mitigation. It is important that cross-sectoral interaction of adaptation and mitigation measures are explicitly recognised if they are to be mainstreamed into policy, so that positive outcomes are enhanced and unintended consequences avoided. [ABSTRACT FROM AUTHOR]

Agricultural sectors play a key role in the economics of climate change. Land as an input to agricultural production is one of the most important links between economy and the biosphere, representing a direct projection of human action on the natural environment. Agricultural management practices and cropping patterns exert an enormous effect on biogeochemical cycles, freshwater availability and soil quality. Agriculture also plays an important role in emitting and storing greenhouse gases. To consistently investigate climate policy and future pathways for the economic and natural environment, a realistic representation of agricultural land use is essential. Top-down Computable General Equilibrium (CGE) models have increasingly been used for this purpose. CGE models simulate the simultaneous equilibrium in a set of interdependent markets, and are especially suited to analyze agricultural markets from a global perspective. However, modeling agricultural sectors in CGE models is not a trivial task, mainly because of differences in temporal and geographic aggregation scales. This study surveys some proposed modeling strategies and highlights different tradeoffs involved in the various approaches. Coupling of top-down and bottom-up models is found to be the most applicable for comprehensive analysis of agriculture in prism of climate change. However, linking interdisciplinary data, methods and outputs is still the major obstacle to be solved for wide-scale implementation. [ABSTRACT FROM AUTHOR]

We have compiled historical greenhouse gas emissions and their uncertainties on country and sector level and assessed their contribution to cumulative emissions and to global average temperature increase in the past and for a the future emission scenario. We find that uncertainty in historical contribution estimates differs between countries due to different shares of greenhouse gases and time development of emissions. Although historical emissions in the distant past are very uncertain, their influence on countries' or sectors' contributions to temperature increase is relatively small in most cases, because these results are dominated by recent (high) emissions. For relative contributions to cumulative emissions and temperature rise, the uncertainty introduced by unknown historical emissions is larger than the uncertainty introduced by the use of different climate models. The choice of different parameters in the calculation of relative contributions is most relevant for countries that are different from the world average in greenhouse gas mix and timing of emissions. The choice of the indicator (cumulative GWP weighted emissions or temperature increase) is very important for a few countries (altering contributions up to a factor of 2) and could be considered small for most countries (in the order of 10%). The choice of the year, from which to start accounting for emissions (e.g. 1750 or 1990), is important for many countries, up to a factor of 2.2 and on average of around 1.3. Including or excluding land-use change and forestry or non-CO gases changes relative contributions dramatically for a third of the countries (by a factor of 5 to a factor of 90). Industrialised countries started to increase CO emissions from energy use much earlier. Developing countries' emissions from land-use change and forestry as well as of CH and NO were substantial before their emissions from energy use. [ABSTRACT FROM AUTHOR]

As economic and emissions scenarios assume convergence of per capita incomes, they are sensitivity to the exchange rate used for international comparison. Particularly, developing countries are project to grow slower with a purchasing power exchange rate than with a market exchange rate. Different exchange rates may lead to scenarios with very different per capita incomes. However, these scenarios also assume convergence of energy intensities, which at least partly offsets the income effect, so that scenarios with different exchange rates would differ less in greenhouse gas emissions. Differences become smaller still if atmospheric concentrations and global warming is considered. However, differences become larger again if one considers the costs of meeting a certain stabilisation target, as the gap between baseline and target is more sensitive to the exchange rate used than the baseline itself. Differences also grow larger if one looks at climate change impacts, which are determined not just by climate change but also by development. The sensitivity to the exchange rate is purely due to imperfect data, imperfect statistical analysis of data, a crude spatial resolution, and imperfect models. [ABSTRACT FROM AUTHOR]

The overlap in sources of greenhouse gas and local air pollutant emissions creates scope for policy measures to limit global warming and improve air quality simultaneously. In a first step, we derive estimates for the air pollution mortality-related component of the social cost of atmospheric release for 6 pollutants and 56 regions in the world. Combining these estimates with emission inventory data highlights that sector contributions to greenhouse gas emissions and air pollution health impacts differ widely across regions. Next, simulations of future emission pathways consistent with the 2 °C and 1.5 °C targets illustrate that strengthening climate policy ambition raises the total value of air quality co-benefits despite lower marginal co-benefits per tonne of greenhouse gas emissions abated. Finally, we use results from a multi-model ensemble to quantify and compare the value of health-related ambient air quality co-benefits of climate policy across sectors and regions. On the global level, overall air quality co-benefits range from $8 to $40 per tonne of greenhouse gases abated in 2030, with median across models and scenarios of $18/tCO2e. These results mask strong differentiation across regions and sectors, with median co-benefits from mitigation in the residential and service sectors in India exceeding $500/tCO2e. By taking a sector- and region-specific perspective, the results presented here reveal promising channels to improve human health outcomes and to ratchet up greenhouse gas reduction efforts to bridge the gap between countries' pledges and the global targets of the Paris Agreement. [ABSTRACT FROM AUTHOR]

The nexus of gender-agriculture-emissions reduction is one of the least explored areas related to agriculture and climate change. This nexus plays an important role in the areas where women's participation in agriculture is high, and the contribution of the agricultural sector to total emission is significant. This study generates evidence on women's labor contribution in rice cultivation and potential reduction of their labor drudgery, including GHG mitigation co-benefits with the adoption of direct seeding and machine transplanting technologies. Using a large number of plot-level data (11,987 data points) from the rice-growing regions of India, the study shows that changing rice production technology from conventional to direct-seeded rice (DSR) and/or machine-transplanted rice (MTR) offers huge potential to reduce women's labor in rice planting (745 million labor-days for DSR and 610 million labor-days for MTR) and greenhouse gases (GHG) emission (34 MtCO2e for DSR and 7 MtCO2e for MTR) at the same time. This potential differs from the agro-ecological region, the level of input use, and women's involvement in rice cultivation. The realization of this gender-responsive GHG mitigation strategy depends on the adoption of these technologies, which rely on several social, economic, and political factors. At the same time, the immense potential for negative implications for some specific groups should not be ignored, but focused on addressing and mitigating those challenges. [ABSTRACT FROM AUTHOR]

We assess uncertainties in projecting future changes in extreme storm surge height (SSH) based on typhoon data extracted from ensemble experiment results with four sea surface temperature (SST) conditions and three global warming scenarios using a single atmospheric global climate model. In particular, this study focus on typhoons passing around the Korean Peninsula (KP) defined as the region of 32 to 40° N and 122 to 132° E. It is predicted the number of the typhoons affecting the KP will decrease by 4~73% while their strength will increase by 0.8~1.4% under the given future conditions. The locations of genesis and lysis of the typhoons are expected to be shifted towards the northwest and northeast for all ensemble experiment conditions, respectively. However, the extent of their change varies depending on the future SST and global warming conditions. Storm surge simulations were carried out by using predicted typhoon data as an external force. It is found that future SST patterns and climate warming scenarios affect future typhoon characteristics, which influences values of extreme SSH and locations of the vulnerable area to storm surge under the future climate conditions. In particular, the values of extreme SSH and the locations of the vulnerable area to storm surge appear to be strongly influenced by both pathway and frequency of intense typhoons. [ABSTRACT FROM AUTHOR]

Grazing systems emit greenhouse gases, which can, under specific agro-ecological conditions, be partly or entirely offset by soil carbon sequestration. However, any sequestration is time-limited, reversible, and at a global level outweighed by emissions from grazing systems. Thus, grazing systems are globally a net contributor to climate change and the time scale of key processes needs to be factored into any mitigation efforts. Failing to do so leads to unrealistic expectations of soil carbon management in grazing systems as a mitigation strategy. Protecting the large carbon stocks in grazing lands is also essential in order to avoid further climate change from additional CO2 release. Despite the time-limited and reversible nature of soil carbon sequestration in grazing lands, sequestration should be promoted in cases where it delivers environmental and agronomic benefits as well as for its potential, particularly on degraded land, to increase the feasibility of limiting global warming to less than 2 or preferably 1.5 °C. Some peer-reviewed sequestration estimates are of a similar order of magnitude to other food systems mitigation options over a 10–20 years period, such as reducing food loss and waste by 15% or aligning diets with current health related dietary-recommendations. However, caution should be applied to such comparisons since mitigation estimates are associated with large uncertainties and will ultimately depend on the economic cost-benefit relation, feasibility of implementation and time frame considered. [ABSTRACT FROM AUTHOR]

One of the biggest challenges to sustainability is lack of public support for policies needed to reduce greenhouse gas emissions. Across three studies, we explored how solution framing impacts public support for financially costly policies designed to reduce greenhouse gas emissions. Study 1 analyzed data from a statewide public opinion poll (N = 771), while studies 2 (N = 100) and 3 (N = 163) were laboratory-based experiments. Specifically, we found that polling questions that asked about a financially costly climate change policy received more support when the goal of the policy was to create efficient technologies than when the goal was to curtail behavior. In addition, we replicate previous research showing that there is a partisan gap for beliefs about global warming and extend this research to show that the partisan gap is not found when looking at support for solutions. The implications of these results for promoting needed climate change policies is discussed. [ABSTRACT FROM AUTHOR]

This study examines the interactions between local air pollutants and greenhouse gas emissions to assess potential synergies and trade-offs between local environmental pollution and climate policies, using the power generation sector in Brazil under different carbon scenarios up to 2050 as a case study. To this end, an integrated approach was developed, combining energy scenarios under different carbon mitigation targets and a local air pollution assessment model, tailored to the context of the Brazilian power sector. Results reveal that there are deep interactions between climate change mitigation and local air pollution abatement strategies. Increasing the diffusion of low-carbon technologies results in both mitigation of climate change and lower terrestrial acidification potential impacts, due to the rapid phase-out of fossil fuel power technologies. However, local air pollution indicators for particulate matter formation and human toxicity may rise in response to greenhouse gas emission mitigation constraints, indicating the existence of potential trade-offs. Some of these trade-offs can be offset by introducing available end-of-pipe pollution control measures reinforced by dedicated air quality policies. [ABSTRACT FROM AUTHOR]

Market-based solutions to climate change are widely advocated by financial actors and policy makers in order to foster a smooth transition to a low-carbon economy. A first important limiting factor to this approach is widely recognized to be the imperfect information on investors' portfolios' exposure to climate-related risks. While better disclosure of climate-relevant information is often recommended as a remedy, the current lack of concise and comparable measures of portfolios' exposure to climate risk fails to provide major investors with the full incentives to reallocate their portfolios. A second limiting factor arises from the fact that in the context of the low-carbon transition, it is not clear how to measure the market share of participants because many economic sectors produce greenhouse gases (GHG) emissions or induce them along the supply chain. The lack of common and concise measures of the relevant market share hampers the ability of policy makers to ensure fair competition policies and the ability of major investors to assess the effects of their own and their competitors' portfolio reallocation. To address these two gaps, we propose two novel and complementary indices: (i) the 'GHG exposure,' capturing the exposure of single investors' portfolios to climate transition risks, and (ii) 'GHG holding,' capturing the market share of each financial actor weighted by its contribution to GHG emissions. We illustrate the use of the indices on a dataset of portfolios of equity holdings and loans in the Euro-Area, and we discuss the policy implications for the low-carbon transition. [ABSTRACT FROM AUTHOR]

While most models project large increases in agricultural drought frequency and severity in the 21st century, significant uncertainties exist in these projections. Here, we compare the model-simulated changes with observation-based estimates since 1900 and examine model projections from both the Coupled Model Inter-comparison Project Phase 3 (CMIP3) and Phase 5 (CMIP5). We use the self-calibrated Palmer Drought Severity Index with the Penman-Monteith potential evapotranspiration (PET) (sc_PDSI_pm) as a measure of agricultural drought. Results show that estimated long-term changes in global and hemispheric drought areas from 1900 to 2014 are consistent with the CMIP3 and CMIP5 model-simulated response to historical greenhouse gases and other external forcing, with the short-term variations within the model spread of internal variability, despite that regional changes are still dominated by internal variability. Both the CMIP3 and CMIP5 models project continued increases (by 50-200 % in a relative sense) in the 21st century in global agricultural drought frequency and area even under low-moderate emissions scenarios, resulting from a decrease in the mean and flattening of the probability distribution functions (PDFs) of the sc_PDSI_pm. This flattening is especially pronounced over the Northern Hemisphere land, leading to increased drought frequency even over areas with increasing sc_PDSI_pm. Large differences exist in the CMIP3 and CMIP5 model-projected precipitation and drought changes over the Sahel and northern Australia due to uncertainties in simulating the African Inter-tropical convergence zone (ITCZ) and the subsidence zone over northern Australia, while the wetting trend over East Africa reflects a robust response of the Indian Ocean ITCZ seen in both the CMIP3 and CMIP5 models. While warming-induced PET increases over all latitudes and precipitation decreases over subtropical land are responsible for mean sc_PDSI_pm decreases, the exact cause of its PDF flattening needs further investigation. [ABSTRACT FROM AUTHOR]

In this study, the contributions from changes in man-made greenhouse gases (GHG), anthropogenic aerosols (AA), and land use (LU), as well as natural solar and volcanic (NAT) forcing changes, to observed changes in surface air temperature (T) and precipitation (P) over global land, especially over arid-semiarid areas, during 1946-2005 are quantified using observations and climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Results show that the anthropogenic (ANT) forcings dominate the ubiquitous surface warming seen in observations and lead to slight increases in precipitation over most land areas, while the NAT forcing leads to small cooling over land. GHG increases are the primary factor responsible for the anthropogenic climate change, while the AA forcing offsets a large part of the GHG-induced warming and P changes. The LU forcing generally contributes little to the T and P changes from 1946 to 2005 over most land areas. Unlike the consistent temperature changes among most model simulations, precipitation changes display a large spread among the models and are incomparable with the observations in spatial distributions and magnitude, mainly due to its large internal variability that varies among individual model runs. Using an optimal fingerprinting method, we find that the observed warming over land during 1946-2005 can be largely attributed to the ANT forcings, and the combination of the ANT and NAT forcings can explain about 85~95% of the observed warming trend over global land as well as over most arid-semiarid regions such as Northern China. However, the anthropogenic influences on precipitation over the past 60 years are generally undetectable over most land areas, including most arid-semiarid regions. This indicates that internal variability is still larger than the forced change for land precipitation. [ABSTRACT FROM AUTHOR]

The political utility of clubs hinges on their ability to provide excludable benefits to members. But in some cases of climate clubs, membership is not easily demarcated, and excludable benefits may be minimal. I argue that these governance initiatives-where membership is fluid and benefits are small-are more accurately defined as 'pseudo-clubs.' Though they function differently than conventional clubs, 'pseudo-clubs' can have considerable political utility. They can lay the foundations for emissions mitigation by solving technical problems associated with the measurement of GHGs. Moreover, since they have low entry costs and minimal sanctions, they can easily attract large numbers of users. With broad membership 'pseudo-clubs' can help promote the uptake of standards, potentially solving coordination problems. However, since measurement is only a precursor to reduction, ultimately, incentives to measure will have to be coupled with rules to reduce emissions. Environmentally effective pseudo-clubs will eventually need the help of governments to shift from coordinating emissions measurement to cooperating on emissions reduction. Pseudo-clubs can serve as an initial building block toward meaningful climate action, but governments will have to finish the job. [ABSTRACT FROM AUTHOR]

The standard US diet contributes to greenhouse gas emissions (GHGE) from both the food system, and from the health system through its contribution to non-communicable diseases. To estimate the potential for diet change to reduce GHGE and improve public health, we analyzed the effect of adopting healthier model diets in the USA on the risk of disease, health care costs, and GHGE. We found that adoption of healthier diets reduced the relative risk of coronary heart disease, colorectal cancer, and type 2 diabetes by 20-45%, US health care costs by US$B 77-93 per year, and direct GHGE by 222-826 kg COe capita year (69-84 kg from the health care system, 153-742 kg from the food system). Emission reductions were equivalent to 6-23% of the US Climate Action Plan's target of a 17% reduction in 2005 GHGE by 2020, and 24-134% of California's target of 1990 GHGE levels by 2020. However, there is potential for investment of health care savings to result in rebound up to and greater than 100%, which would increase net GHGE. Given the urgency of improving public health and of mitigating GHGE over the short term, the potential contribution of diet change, and the options for reducing rebound, deserve more research in support of policy. [ABSTRACT FROM AUTHOR]

The Paris Climate Agreement sets out an aggressive goal of limiting global average warming to well below 2 °C. As a first step, virtually all countries have put forth greenhouse gas emission reduction pledges in the form of nationally determined contributions, or NDCs, for the 2030 timeframe. Our analysis looks beyond the NDCs to explore potential post-2030 regional emissions reduction participation and ambition. For each scenario, we examine the implications for global emissions and long-term temperature. We then evaluate the regional consequences for energy systems and ensuing costs. We conclude by reflecting on the additional global abatement costs of tightening temperature goals. Overall, this study provides a multidimensional characterization of the scale of regional effort supporting climate outcomes, details important to decision-makers as they consider mid-century emissions targets, and long-run climate objectives. [ABSTRACT FROM AUTHOR]

While ecosystems-based adaptation (EbA) has been received with great interest, the requirements for EbA implementation and its precise benefits under future climate change are unclear. Furthermore, EbA's overlap with environmental, and development policy agendas leads to ambiguity regarding what actions fall under the rubric of EbA. We analyze the projects identified by the UNFCCC as examples of EbA to understand how EbA is conceptualized and promoted by the international community. Addressing climate change is the primary objective of 58% of the EbA projects; the other 42% of projects provide adaptation benefits yet are not primarily driven by climate change. A project's adaptation targeting is tied to its information needs. Projects whose primary objective is to address climate change are more likely to use detailed climate projections than projects whose primary objective is to address natural hazards, development or ecosystems degradation. A majority of projects do not address uncertainty in future climate change or in adaptation benefits, nor do they track adaptation outcomes. This prevalent lack of monitoring highlights the possibility of a gap between expected and realized adaptation outcomes. It also represents a lost opportunity for improving knowledge of the thresholds of effectiveness of EbA and of factors influencing EbA efficacy. [ABSTRACT FROM AUTHOR]