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As the world's largest fossil fuels exporter, Russia is one of the key countries for addressing global climate change. However, it has never demonstrated any significant ambitions to reduce greenhouse gas (GHG) emissions. This paper applies ideational research methodology to identify the structural differences in economic, political, and social normative contexts between industrialized fossil fuel importing economies and Russia that lead to the fundamental gap in motivations driving decarbonization efforts. Russia is unlikely to replicate the approach to the green transition and climate policy instruments of energy-importing countries. In order to launch decarbonization in Russia, interested stakeholders need to frame climate policies in Russia differently. Specifically, the framing must address the priority of diversification as a means to adapting the national economy to a new green landscape, the combination of diverse channels for decarbonization, the promotion of energy-efficiency, closer attention to climate-related forest projects, and linkage of climate change with other environmental problems. Moreover, considering Russia's emissions as a part of the global economic system and shifting from a simplistic national focus on GHG emissions reduction would help coordinate policies through dialogue between exporters and importers of fossil fuel energy-intensive goods, which is essential for the global movement towards a net-zero future. [ABSTRACT FROM AUTHOR]

Combining bioenergy and carbon dioxide (CO) capture and storage (CCS) technologies (BECCS) has the potential to remove CO from the atmosphere while producing useful energy. BECCS has played a central role in scenarios that reduce climate forcing to low levels such as 2.6 Wm. In this paper we consider whether BECCS is essential to limiting radiative forcing (RF) to 2.6 Wm by 2100 using the Global Change Assessment Model, a closely coupled model of biogeophysical and human Earth systems. We show that BECCS can potentially reduce the cost of limiting RF to 2.6 Wm by 2100 but that a variety of technology combinations that do not include BECCS can also achieve this goal, under appropriate emissions mitigation policies. We note that with appropriate supporting land-use policies terrestrial sequestration could deliver carbon storage ranging from 200 to 700 PgCO-equiavalent over the 21st century. We explore substantial delays in participation by some geopolitical regions. We find that the value of BECCS is substantially higher under delay and that delay results in higher transient RF and climate change. However, when major regions postponed mitigation indefinitely, it was impossible to return RF to 2.6 Wm by 2100. Neither finite land resources nor finite potential geologic storage capacity represented a meaningful technical limit on the ability of BECCS to contribute to emissions mitigation in the numerical experiments reported in this paper. [ABSTRACT FROM AUTHOR]

Rapid cuts in greenhouse gas emissions require an almost complete transformation of the energy system to low carbon energy sources. Little consideration has been given to the potential adverse carbon consequences associated with the technology transition. This paper considers the embodied emissions that will occur to replace the UK's fossil fuel-reliant energy supply with low carbon sources. The analysis generates a number of representative scenarios where emissions embodied in energy systems are integrated within current national climate and energy policy objectives. The embodied emissions associated with a new low carbon energy system are lower than the emissions reduction associated with the low carbon energy sources, confirming that there is a carbon return on investment. However, even if the UK reaches its 2050 territorial climate target, it is estimated that by 2050 an additional 200 Mt CO emissions are generated overseas (compared to 128 Mt generated within the UK) in the production of imported fuels and infrastructure components. The cost-optimal model results suggest that more electrification would need to occur, supported by nuclear energy, mainly in replacement of natural gas to mitigate these emissions. However, due to a number of deployment barriers, other policy interventions along the energy supply chain are likely needed, which are discussed alongside the model results. There could be more emphasis on an absolute reduction in energy demand to reduce the scale of change needed in supplying energy; new business models oriented towards performance and not sales; and existing trade schemes and international effort-sharing frameworks could be extended. [ABSTRACT FROM AUTHOR]

In addition to lower carbon dioxide emissions, policies to reduce fossil fuel combustion can yield substantial air quality co-benefits via reduced emissions of co-pollutants such as particulate matter and air toxics. If co-pollutant intensity (the ratio of co-pollutant impacts to carbon dioxide emissions) varies across pollution sources, efficient policy design would seek greater emissions reductions where co-benefits are higher. The distribution of co-benefits also raises issues of environmental equity. This paper presents evidence on intersectoral, intrasectoral and spatial variations in co-pollutant intensity of industrial point sources in the United States, and discusses options for integrating co-benefits into climate policy design to advance efficiency and equity. [ABSTRACT FROM AUTHOR]

This paper provides a novel assessment of the role of direct air capture of CO from ambient air (DAC) on the feasibility of achieving stringent climate stabilization. We use the WITCH energy-economy-climate model to investigate the long term prospects of DAC, implementing a technological specification based on recent estimates by the American Physical Society (APS ). Assuming global cooperation on a stringent climate policy we find that: (1) DAC is deployed only late in century, after other low carbon options, though at a very significant scale; (2) DAC has an impact on the marginal and total abatement costs (reducing them) and on the timing of mitigation (postponing it); (3) DAC also allows for a prolonged use of oil, with a positive welfare impact for energy exporting countries. Finally, we assess the role of DAC in a less than ideal climate policy by exploring its potential for engaging energy exporting countries in climate mitigation activities by means of a 'clean oil' market in which oil exporters can sell oil decarbonized via DAC. [ABSTRACT FROM AUTHOR]

In recent years a body of literature has arisen on the topic of how to compose the optimal portfolio of mitigation options. The focus has been mainly on options involving shifts from high- to low- or even negative-carbon technologies. Natural sinks play an important role in any attempt to stabilize atmospheric CO and usually enter as a constant term in the overall carbon budget. In this paper, we introduce natural sinks to the carbon management problem and analyze the implications for negative emission technology deployment and the overall mitigation strategy. Amongst other sensitivity analyses, we also investigate the impact of uncertainty in the carbon sink, which we find to raise the importance of negative emissions in the mitigation portfolio significantly lowering the cost of the policy mix. [ABSTRACT FROM AUTHOR]

Motorized individual transport strongly contributes to global CO emissions, due to its intensive usage of fossil fuels. Current political efforts addressing this issue (i.e. emission performance standards in the EU) are directed towards car manufacturers. This paper focuses on the demand side. It examines whether CO emissions per kilometer is a relevant attribute in car choices. Based on a choice experiment among potential car buyers from Germany, a mixed logit specification is estimated. In addition, distributions of willingness-to-pay measures for an abatement of CO emissions are obtained. The results suggest that the emissions performance of a car matters substantially, but its consideration varies heavily across the sampled population. In particular, some evidence on gender, age and education effects on climate concerns is provided. [ABSTRACT FROM AUTHOR]

The use of analogies and repeated feedback might help people learn about the dynamics of climate change. In this paper, we study the influence of repeated feedback on the control of a carbon-dioxide (CO) concentration to a goal level in a Dynamic Climate Change Simulator (DCCS) using the 'bathtub' analogy. DCCS is a simplification of the complex climate system into its essential elements: CO concentration (stock); man-made CO emissions (inflow); and natural CO removal or absorption in the atmosphere (outflow). In a laboratory experiment involving DCCS, we manipulated feedback delays in two ways: the frequency of emission decisions and the rate of CO absorption from the atmosphere (climate dynamics). Our results revealed that participants' ability to control the CO concentration generally remained poor even in conditions where they were allowed to revise their emission decisions frequently (i.e., every 2 years) and where the climate dynamics were rapid (i.e., 1.6% of CO concentration was removed every year). Participants' control of the concentration only improved with repeated feedback in conditions of lesser feedback delay. Moreover, the delay due to climate dynamics had a greater effect on participants' control than the delay due to emission decisions frequency. We provide future research directions and highlight the potential of using simulations like DCCS to help people learn about dynamics of Earth's climate. [ABSTRACT FROM AUTHOR]

The relationship between long-term climate goals and short/medium-term emission targets forms crucial information for the design of international climate policy. Since IPCC's 4th Assessment Report (AR4), a large number of new scenario studies have been published. This paper reviews this new literature and finds that there is more flexibility in the timing of short-term emission reductions compared to the earlier scenarios assessed by the AR4. For instance, the current literature suggests that a peak of emissions in 2020 and even 2030 would be consistent with limiting temperature change to about 2°C in the long term. The timing when emissions peak depends on whether negative emissions in the long-term can be achieved. The recent scenarios further indicate that global emissions by 2050 should be 40-80% below 2000 levels. Above all, the paper argues that there is no clear, single 'law' that would directly determine the required emissions levels in 2020, but that instead policy-makers need to consider trade-offs between the likelihood of achieving long-term targets, the short-term costs, and their expectation with respect to future technologies (and their possible failure). The higher flexibility might be important in finding acceptable agreements on international climate policy. [ABSTRACT FROM AUTHOR]

Preparatory talks to the next round of negotiations seem to indicate that a comprehensive agreement to mitigate climate change will not be easily attainable, despite the intentions of the US administration and the high expectations surrounding the Copenhagen meeting. One key reason is to what extent fast growing economies, and especially China, should take actions to reduce their growth of emissions. This paper argues that a turning point for international negotiations on climate change could be achieved if China were to agree on carbon obligations in the future. Results from modelling work suggest that the optimal investment behaviour is to anticipate the implementation of a climate policy by roughly 10 years, and that thus future commitments—if credible—could lead to significantly earlier steps towards carbon mitigation. If fast growing economies, and foremost China, believe in the long term objective of global stabilization of carbon concentrations, it might be economically rationale to sign on future targets, provided developed countries take on immediate action. Such a provision could be beneficial for both the developing and developed world. [ABSTRACT FROM AUTHOR]

Many European politicians argue that the EU should set tougher emission targets than what is required by the Kyoto protocol, and moreover, that emission trading with other countries outside EU should be limited so as to keep emission quota prices high. One of the arguments, frequently cited for such a policy, is the need for technological development. However, the literature on climate change and technological innovation does not unambiguously support the need for setting high emission taxes today. In this paper we investigate the relationship between emission taxes and technological change further by modeling innovation activity explicitly. In our model both the amount of R&D and the amount of carbon abatement are decided in a decentralized way by the market as a response to an emission tax. Moreover, we introduce several distinct failures in the market for new innovations, among others, insufficient patent protection and intertemporal knowledge spill-overs. Our findings suggest that governments should under some circumstances set a higher carbon tax today if we have technological change driven by R&D than if we have pure exogenous technological change. Based on numerical simulations these circumstances are (a) positive intertemporal knowledge spillovers and/or (b) weak patent protection. [ABSTRACT FROM AUTHOR]

Carbon dioxide emissions are the main cause of anthropogenic climate change and play a central role in discussions on climate change mitigation. Previous research has demonstrated that national carbon dioxide emissions are driven mainly by population size and wealth. However, the variation in per capita emissions of nations with similar standards of living and similar population is huge. In this paper we investigate the drivers of national per capita carbon dioxide emissions over and above already known factors. In particular, we extend previous research by taking into account countries' shares of imports and exports, indicators of political interventions such as energy prices, and the use of renewable energy sources. Moreover, we also examine whether international commitments, such as the ones made by many nations at climate summits of the United Nations, matter. We use country-level data from 1980 to 2014 and estimate fixed effects panel regression models. In accordance with former research we find no environmental Kuznets curve with respect to carbon dioxide per capita emission levels. However, higher energy prices and the availability of alternative energy sources both reduce emissions. Furthermore, voluntary international environmental commitments also motivate countries to reduce carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

This paper analyses the technology choices of countries that prioritized transport as a sector in Asia under the Technology Needs Assessment project. The countries used a wide variety of criteria to prioritize technologies which were related to the benefits technologies would provide, costs of technologies and availability of technology charactersitics. Non-motorized transport, mass transit and technologies that improve vehicle energy efficiency emerged as the three most preferred technology choices for the countries. These technology choices can be appropriate candidates for nationally appropriate mitigations actions (NAMA) given their strong contribution for developmentand therefore a methodology based on input-output decomposition analysis isproposed for analysing economy wide CO emissions reductions. The methodologyhas been applied for the transport sector of Lebanon where alternative fuels,improvement to cars (private and taxis) and buses for public transport were prioritized by stakeholders. The economy-wide CO emission reduce by 2,269 thousand tons by 2020 if the prioritized technologies are implemented in Lebanon. Fuel mix effect and structural effect would reduce CO emission by 2,611 thousand tons, while the final demand effect would increase the CO emission by 342 thousand tons. [ABSTRACT FROM AUTHOR]

In this paper we study the impact of alternative metrics on short- and long-term multi-gas emission reduction strategies and the associated global and regional economic costs and emissions budgets. We compare global warming potentials with three different time horizons (20, 100, 500 years), global temperature change potential and global cost potentials with and without temperature overshoot. We find that the choice of metric has a relatively small impact on the CO budget compatible with the 2° target and therefore on global costs. However it substantially influences mid-term emission levels of CH, which may either rise or decline in the next decades as compared to today's levels. Though CO budgets are not affected much, we find changes in CO prices which substantially affect regional costs. Lower CO prices lead to more fossil fuel use and therefore higher resource prices on the global market. This increases profits of fossil-fuel exporters. Due to the different weights of non-CO emissions associated with different metrics, there are large differences in nominal CO equivalent budgets, which do not necessarily imply large differences in the budgets of the single gases. This may induce large shifts in emission permit trade, especially in regions where agriculture with its high associated CH emissions plays an important role. Furthermore it makes it important to determine CO equivalence budgets with respect to the chosen metric. Our results suggest that for limiting warming to 2 °C in 2100, the currently used GWP100 performs well in terms of global mitigation costs despite its conceptual simplicity. [ABSTRACT FROM AUTHOR]

Carbon Capture and Storage (CCS) can be a valuable CO mitigation option, but what role CCS will play in the future is uncertain. In this paper we analyze the results of different integrated assessment models (IAMs) taking part in the 27th round of the Energy Modeling Forum (EMF) with respect to the role of CCS in long term mitigation scenarios. Specifically we look into the use of CCS as a function of time, mitigation targets, availability of renewables and its use with different fuels. Furthermore, we explore the possibility to relate model results to general and CCS specific model assumptions. The results show a wide range of cumulative capture in the 2010-2100 period (600-3050 GtCO), but the fact that no model projects less than 600 GtCO indicates that CCS is considered to be important by all these models. Interestingly, CCS storage rates are often projected to be still increasing in the second half of this century. Depending on the scenario, at least six out of eight, up to all models show higher storage rates in 2100 than in 2050. CCS shares in cumulative primary energy use are in most models increasing with the stringency of the target or under conservative availability of renewables. The strong variations of CCS deployment projection rates could not be related to the reported differences in the assumptions of the models by means of a cross-model comparison in this sample. [ABSTRACT FROM AUTHOR]

In this paper I discuss the nature of geoengineering, some of its attractions, and some reasons for concern. I claim that there is confusion in the use of the term ‘geoengineering’ that is related to larger concerns about the language in which responses to climate change are discussed. I conclude that despite some reasonable grounds for suspicion, research in areas that involve carbon dioxide removal and solar radiation management should go on as part of the general portfolio of climate-related research, competing with the full panoply of other possible responses to climate change. [ABSTRACT FROM AUTHOR]

The transition from autocracy to democracy may lead a country to break-up. The break-ups of the USSR and Yugoslavia led to sharp falls in the level of emissions (while pre- and post-crisis trends are similar). If something like that would happen in China, an event with an unknown but small probability, projected emissions would fall by 50 % or more. The effect of a break-up on emissions in 2050 is larger than the difference between the SRES scenarios. [ABSTRACT FROM AUTHOR]

This paper synthesizes the results from the model intercomparison exercise among regionalized global energy-economy models conducted in the context of the RECIPE project. The economic adjustment effects of long-term climate policy are investigated based on the cross-comparison of the intertemporal optimization models ReMIND-R and WITCH as well as the recursive dynamic computable general equilibrium model IMACLIM-R. A number of robust findings emerge. If the international community takes immediate action to mitigate climate change, the costs of stabilizing atmospheric CO concentrations at 450 ppm (roughly 530-550 ppm-e) discounted at 3% are estimated to be 1.4% or lower of global consumption over the twenty-first century. Second best settings with either a delay in climate policy or restrictions to the deployment of low-carbon technologies can result in substantial increases of mitigation costs. A delay of global climate policy until 2030 would render the 450 ppm target unachievable. Renewables and CCS are found to be the most critical mitigation technologies, and all models project a rapid switch of investments away from freely emitting energy conversion technologies towards renewables, CCS and nuclear. Concerning end use sectors, the models consistently show an almost full scale decarbonization of the electricity sector by the middle of the twenty-first century, while the decarbonization of non-electric energy demand, in particular in the transport sector remains incomplete in all mitigation scenarios. The results suggest that assumptions about low-carbon alternatives for non-electric energy demand are of key importance for the costs and achievability of very low stabilization scenarios. [ABSTRACT FROM AUTHOR]

This paper analyzes the regional distribution of climate change mitigation costs in a global cap-and-trade regime. Four stylized burden-sharing rules are considered, ranging from GDP-based permit allocations to schemes that foresee a long-term convergence of per-capita emission permits. The comparison of results from three structurally different hybrid, integrated energy-economy models allows us to derive robust insights as well as identify sources of uncertainty with respect to the regional distribution of the costs of climate change mitigation. We find that regional costs of climate change mitigation may deviate substantially from the global mean. For all models, the mitigation cost average of the four scenarios is higher for China than for the other macro-regions considered. Furthermore, China suffers above-world-average mitigation costs for most burden-sharing rules in the long-term. A decomposition of mitigation costs into (a) primary (domestic) abatement costs and (b) permit trade effects, reveals that the large uncertainty about the future development of carbon prices results in substantial uncertainties about the financial transfers associated with carbon trade for a given allocation scheme. This variation also implies large uncertainty about the regional distribution of climate policy costs. [ABSTRACT FROM AUTHOR]

In this paper we argue that the financial provisions of the Copenhagen Accord, if used primarily to mitigate greenhouse gas (GHGs) emissions, could compensate the lack of more energetic action on the domestic mitigation side. In order to maximize the mitigation potential, the Copenhagen Green Climate Fund (CGCF) should be transformed into the International Bank for Emissions Allowance Acquisition (IBEAA) envisaged by Bradford (). We estimate that 50 percent of the CGCF in 2020 (50 US billions) could finance from 2.1 to 3.3 Gt CO2-eq emission reductions, depending on the domestic mitigation effort of Annex I and Non-Annex I countries. We construct a matrix that shows the level of GHGs emissions in 2020 under all possible combinations of abatement pledges and international mitigation financing, thus highlighting a rich set of options to reach the same level of GHGs emissions in 2020. [ABSTRACT FROM AUTHOR]

The idea of market-based carbon emission trading and carbon taxes is gaining in popularity as a global climate change policy instrument. However, these mechanisms might not necessarily have a positive outcome unless their value reflects socioeconomic and environmental impacts and regulations. Moreover, the fact that they have various inherent exogenous and endogenous uncertainties raises serious concerns about their ability to reduce emissions in a cost-effective way. This paper aims to introduce a simple stochastic model that allows the robustness of economic mechanisms for emission reduction under multiple natural and human-related uncertainties to be analyzed. Unlike standard equilibrium state analysis, the model shows that the explicit introduction of uncertainties regarding emissions, abatement costs, and equilibrium states makes it almost impossible for existing market-based trading and carbon taxes to be environmentally safe and cost-effective. Here we propose a computerized multi-agent trading model. This can be viewed as a prototype to simulate an emission trading market that is regulated in a decentralized way. We argue that a market of this type is better equipped to deal with long-term emission reductions, their direct regulation, irreversibility, and 'lock-in' equilibria. [ABSTRACT FROM AUTHOR]

In this paper we apply a linear regression with spatial random effect to model geographically distributed emission inventory data. The study presented is on NO emission assessments for municipalities of southern Norway and on activities related to emissions (proxy data). Taking advantage of the spatial dimension of the emission process, the method proposed is intended to improve inventory extension beyond its earlier coverage. For this, the proxy data are used. The conditional autoregressive model is used to account for spatial correlation between municipalities. Parameter estimation is based on the maximum likelihood method and the optimal predictor is developed. The results indicate that inclusion of a spatial dependence component lead to improvement in both representation of the observed data set and prediction. [ABSTRACT FROM AUTHOR]

In accordance with the concept that only full accounting of major greenhouse gases corresponds to the goals of the United Nations Framework Convention on Climate Change and its Kyoto Protocol, this paper considers uncertainties of regional (national) terrestrial biota Full Carbon Accounting (FCA), both those already achieved and those expected. We analyze uncertainties of major components of the FCA of forest ecosystems of a large boreal region in Siberia (~300 × 10 ha). Some estimates for forests of other regions and Russia as a whole are used for comparison. The systems integration of available information sources and different types of models within the landscape-ecosystem approach are shown to have enabled an estimation of the major carbon fluxes (Net Primary Production, NPP, and heterotrophic respiration, HR) for the region for a single year at the level of 7-12% (confidential interval, CI, 0.9), Net Ecosystem Production (NEP) of 35-40%, and Net Biome Production (NBP) of 60-80%. The most uncertain aspect is the assessment of change in the soil carbon pool, which limits practical application of a pool-based approach. Regionalization of global process-based models, introduction of climatic data in empirical models, use of an appropriate time period for accounting and reporting, harmonization and multiple constraints of estimates obtained by different independent methods decrease the above uncertainties of NEP and NBP by about half. The results of this study support the idea that FCA of forest ecosystems is relevant in the post-Kyoto international negotiation process. [ABSTRACT FROM AUTHOR]

Climate sensitivity and climate-carbon cycle feedbacks interact to determine how global carbon and energy cycles will change in the future. While the science of these connections is well documented, their economic implications are not well understood. Here we examine the effect of climate change on the carbon cycle, the uncertainty in climate outcomes inherent in any given policy target, and the economic implications. We examine three policy scenarios-a no policy 'Reference' (REF) scenario, and two policies that limit total radiative forcing-with four climate sensitivities using a coupled integrated assessment model. Like previous work, we find that, within a given scenario, there is a wide range of temperature change and sea level rise depending on the realized climate sensitivity. We expand on this previous work to show that temperature-related feedbacks on the carbon cycle result in more mitigation required as climate sensitivity increases. Thus, achieving a particular radiative forcing target becomes increasingly expensive as climate sensitivity increases. [ABSTRACT FROM AUTHOR]

Can near-term public support of renewable energy technologies contain the increase of mitigation costs due to delays of implementing emission caps at the global level? To answer this question we design a set of first and second best scenarios to analyze the impact of early deployment of renewable energy technologies on welfare and emission timing to achieve atmospheric carbon stabilization by 2100. We use the global multiregional energy-economy-climate hybrid model REMIND-R as a tool for this analysis. An important design feature of the policy scenarios is the timing of climate policy. Immediate climate policy contains the mitigation costs at less than 1% even if the CO concentration target is 410 ppm by 2100. Delayed climate policy increases the costs significantly because the absence of a strong carbon price signal continues the carbon intensive growth path. The additional costs can be decreased by early technology policies supporting renewable energy technologies because emissions grow less, alternative energy technologies are increased in capacity and their costs are reduced through learning by doing. The effects of early technology policy are different in scenarios with immediate carbon pricing. In the case of delayed climate policy, the emission path can be brought closer to the first-best solution, whereas in the case of immediate climate policy additional technology policy would lead to deviations from the optimal emission path. Hence, technology policy in the delayed climate policy case reduces costs, but in the case of immediate climate policy they increase. However, the near-term emission reductions are smaller in the case of delayed climate policies. At the regional level the effects on mitigation costs are heterogeneously distributed. For the USA and Europe early technology policy has a positive welfare effect for immediate and delayed climate policies. In contrast, India looses in both cases. China loses in the case of immediate climate policy, but profits in the delayed case. Early support of renewable energy technologies devalues the stock of emission allowances, and this effect is considerable for delayed climate policies. In combination with the initial allocation rule of contraction and convergence a relatively well-endowed country like India loses and potential importers like the EU gain from early renewable deployment. [ABSTRACT FROM AUTHOR]

Carbon dioxide removal (CDR) describes a suite of controversial approaches to mitigating climate change that involve removing existing carbon dioxide from the atmosphere. Through an online survey experiment with US adults (N = 980), we examine three factors that may shape public support for different types of CDR strategies: (1) perceptions that CDR tampers with nature, (2) individual-level variation in the degree to which people are uncomfortable with activities that tamper with nature, and (3) information about the risks and benefits associated with each CDR strategy. Using a moderated mediation analysis, we find that support for different CDR strategies is, in part, a function of how much each strategy is perceived to tamper with nature. Support for bioenergy with carbon capture and storage (BECCS) and direct air capture (DAC) was lower than support for afforestation and reforestation (AR), as BECCS and DAC were perceived to tamper with nature more. These effects were particularly strong among individuals generally opposed to the idea of humans interfering with natural processes. Moreover, we find evidence that describing the risks and benefits of each CDR strategy dampens support; for AR and BECCS, this effect was again mediated through perceptions of tampering, while for DAC, the effect of describing these tradeoffs appeared to operate independently of perceived tampering. We conclude that policymakers and science communicators need to be mindful of how CDR strategies are described to the public, as perceptions of tampering with nature may be an important driver of their acceptance. [ABSTRACT FROM AUTHOR]

Conditional forecasts of US economic and energy sector activity are developed using information from a dynamic, data-rich environment. The forecasts are conditional on a path for carbon dioxide emissions outlined in the US Environmental Protection Agency’s Clean Power Plan (CPP) and are estimated based on a factor-augmented autoregressive framework. Results suggest that overall growth will be slower under the CPP than it would otherwise; however, economic growth and CO2 reductions can be achieved simultaneously. There are little differences between unconditional (business-as-usual) and conditional forecasts of the variables in the early part of the forecast period; the impacts of the CPP are small while the constraints on carbon dioxide are less stringent. The results serve as a data-driven complement to structural analyses of policy change in the energy sector. [ABSTRACT FROM AUTHOR]

Emissions of CO2 from the EU can be estimated using different system boundaries, depending on the policy question. We analyze and compare the trends in territorial emissions (1990-2016) and consumption-based emissions and emissions embodied in trade (1990-2014). We find the Global Financial Crisis (GFC) in 2008 was an important turning point. Territorial emissions were roughly stable in the years before the GFC but have since declined. Consumption-based emissions rose from 2000 to the GFC but then declined in concert with territorial emissions. A Kaya identity decomposition suggests that the main factor pushing the EU’s territorial emissions up before the GFC was a growth in GDP, balanced by constant improvements in energy and carbon intensity. The large increase in consumption-based emissions up to the GFC was mainly due to emissions from the production of imported manufactured goods, particularly from China. After the GFC, the Kaya identity decomposition suggests that lower GDP growth facilitated a sustained decrease in territorial emissions. The decline in consumption-based emissions since the GFC was partly due to decreasing territorial emissions but accelerated due to a decrease in the emissions from the production of imported products from China. Preliminary data indicates that EU CO2 emissions have increased from 2014 to 2017, with the Kaya identity decomposition suggesting the increase is due to a return to stronger GDP growth. [ABSTRACT FROM AUTHOR]

Avoiding dangerous climate change will require a rapid transition away from fossil fuels. By some estimates, global consumption and production of fossil fuels—particularly coal and oil—will need to end almost entirely within 50 years. Given the scale of such a transition, nations may need to consider policies that constrain growth in fossil fuel supplies in addition to those that reduce demand. Here, we examine the emissions implications of a supply-constraining measure that was rapidly gaining momentum in the United States (US) under the Obama administration: ceasing the issuance of new leases for fossil fuel extraction on federal lands and waters. Such a measure could reduce global carbon dioxide emissions by an estimated 280 million tons annually by 2030, comparable to that of other major climate policies adopted or considered by the Obama administration. Our findings suggest that measures to constrain fossil fuel supply—though not currently viable in a US Trump administration—deserve further consideration at subnational levels in the US or by other countries now, and by future US administrations. [ABSTRACT FROM AUTHOR]

The Paris Agreement states that, relative to pre-industrial times, the increase in global average temperature should be kept to well below 2 °C and efforts should be made to limit the temperature increase to 1.5 °C. Emissions scenarios consistent with these targets are derived. For an eventual 2 °C warming target, this could be achieved even if CO2 emissions remained positive. For a 1.5 °C target, CO2 emissions could remain positive, but only if a substantial and long-lasting temperature overshoot is accepted. In both cases, a warming overshoot of 0.2 to 0.4 °C appears unavoidable. If the allowable (or unavoidable) overshoot is small, then negative emissions are almost certainly required for the 1.5 °C target, peaking at negative 1.3 GtC/year. In this scenario, temperature stabilization occurs, but cumulative emissions continue to increase, contrary to a common belief regarding the relationship between temperature and cumulative emissions. Changes to the Paris Agreement to accommodate the overshoot possibility are suggested. For sea level rise, tipping points that might lead to inevitable collapse of Antarctic ice sheets or shelves might be avoided for the 2 °C target (for major ice shelves) or for the 1.5 °C target for the West Antarctic Ice Sheet. Even with the 1.5 °C target, however, sea level will continue to rise at a substantial rate for centuries. [ABSTRACT FROM AUTHOR]

Nearly all research on public perceptions of climate engineering has been conducted in wealthy, developed countries. However, understanding perspectives from vulnerable populations is critical to inclusive, democratic debate on both research and governance. This study utilized in-depth interviews to explore the perspectives of vulnerable populations in the South Pacific, Sub-Saharan Africa, and the North American Arctic. Interviewees in this study were desperate for solutions to climate change and therefore willing to consider climate engineering. However, their willingness to consider climate engineering could be characterized as both deeply reluctant and highly conditional. Interviewees expressed a number of concerns about potential social and political implications of engineering the climate. They also described conditions that may need to be met to ensure that future climates (engineered or otherwise) are more equitable. [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]

Blue carbon refers to the considerable amounts of carbon sequestered by mangroves, seagrass beds, tidal marshes and other coastal and marine vegetated ecosystems. At the present time, carbon market mechanisms to compensate those conserving blue carbon ecosystems, and thus reducing carbon emissions, are not yet in place. The ecosystem services provided by coastal vegetated ecosystems extend beyond their carbon storage capacity, and include their contribution to fishery production; shoreline protection; provision of habitat for wildlife and migratory species; flood water attenuation; nutrient cycling, pollution buffering; as well as their cultural, spiritual, subsistence and recreational uses. Because these services are of high economic, social and cultural value, the management and protection of blue carbon ecosystems could build collaboration between climate change and biodiversity practitioners on the national and international level. Such collaboration would also allow for the transfer of lessons learned from coastal management and conservation activities to carbon mitigation projects, and would include the need to work closely together with indigenous peoples and local communities. Resulting management activities on the local level could utilize and strengthen traditional knowledge and management systems related to blue carbon ecosystems, and increase both the resilience of biodiversity and that of coastal communities, as well as provide for long-term storage of blue carbon. While the challenge of scaling up local initiatives remains, some concrete examples already exist, such as the network of locally-managed marine areas (LMMAs) in the Pacific and beyond. [ABSTRACT FROM AUTHOR]

The use of liquid biofuels has expanded over the past decade in response to policies such as the U.S. Renewable Fuel Standard (RFS) that promote their use for transportation. One rationale is the belief that biofuels are inherently carbon neutral, meaning that only production-related greenhouse gas (GHG) emissions need to be tallied when comparing them to fossil fuels. This assumption is embedded in the lifecycle analysis (LCA) modeling used to justify and administer such policies. LCA studies have often found that crop-based biofuels such as corn ethanol and biodiesel offer at least modest net GHG reductions relative to petroleum fuels. Data over the period of RFS expansion enable empirical assessment of net CO emission effects. This analysis evaluates the direct carbon exchanges (both emissions and uptake) between the atmosphere and the U.S. vehicle-fuel system (motor vehicles and the physical supply chain for motor fuels) over 2005-2013. While U.S. biofuel use rose from 0.37 to 1.34 EJ/yr over this period, additional carbon uptake on cropland was enough to offset only 37 % of the biofuel-related biogenic CO emissions. This result falsifies the assumption of a full offset made by LCA and other GHG accounting methods that assume biofuel carbon neutrality. Once estimates from the literature for process emissions and displacement effects including land-use change are considered, the conclusion is that U.S. biofuel use to date is associated with a net increase rather than a net decrease in CO emissions. [ABSTRACT FROM AUTHOR]

Incorporating carbon offsets in the design of cap-and-trade programs remains a controversial issue because of its potential unintended impacts on emissions. At the heart of this discussion is the issue of crediting of emissions reductions. Projects can be correctly, over- or under-credited for their actual emissions reductions. We develop a unified framework that considers the supply of offsets within a cap-and-trade program that allows us to compare the relative impact of over-credited offsets and under-credited emissions reductions on overall emissions under different levels of baseline stringency and carbon prices. In the context of a national carbon pricing scheme that includes offsets, we find that the emissions impacts of over-credited offsets can be fully balanced out by under-credited emissions reductions without sacrificing a significant portion of the overall supply of offsets, provided emissions baselines are stringent enough. In the presence of high predicted business-as-usual (BAU) emissions uncertainty or low carbon prices, to maintain the environmental integrity of the program, baselines need to be set at stringent levels, in some cases below 50 percent of predicted BAU emissions. As predicted BAU emissions uncertainty declines or as the carbon market achieves higher equilibrium prices, however, less stringent baselines can balance out the emissions impacts of over-credited offsets and under-credited emissions reductions. These results imply that to maintain environmental integrity of offsets programs, baseline stringency should be tailored to project characteristics and market conditions that influence the proportion of over-credited offsets to under-credited emissions reductions. [ABSTRACT FROM AUTHOR]

An effective climate agreement is urgently required, yet conflict between parties prevails over cooperation. Thanks to advances in science it is now possible to quantify the global carbon budget, the amount of available cumulative CO emissions before crossing the 2 C threshold (Meinshausen et al. Nature 458(7242):1158-1162, ). Countries carbon claims, however, exceed this. Historically such situations have been tackled with bankruptcy division rules. We argue that framing climate negotiations as a classical conflicting claims problem (O'Neill Math Soc Sci 2(4):345-371, ) may provide for an effective climate policy. We analyze the allocation of the global carbon budget among parties claiming the maximum emissions rights possible. Based on the selection of some desirable principles, we propose an efficient and sustainable allocation of the available carbon budget for the period 2000 to 2050 taking into account different risk scenarios. [ABSTRACT FROM AUTHOR]

Large amounts of carbon are stored as permafrost within the Arctic and sub-Arctic regions. As permafrost thaws due to climate warming, carbon dioxide and methane are released. Recent studies indicate that the pool of carbon susceptible to future thaw is higher than was previously thought and that more carbon could be released by 2100, even under low emission pathways. We use an integrated model of the climate and the economy to study how including these new estimates influence the control of climate change to levels that will likely keep the temperature increase below 2 °C (radiative forcing of 2.6 Wm). According to our simulations, the fossil fuel and industrial CO emissions need to peak 5-10 years earlier and the carbon budget needs to be reduced by 6-17 % to offset this additional source of warming. The required increase in carbon price implies a 6-21 % higher mitigation cost to society compared to a situation where emissions from permafrost are not considered. Including other positive climate feedbacks, currently not accounted for in integrated assessment models, could further increase these numbers. [ABSTRACT FROM AUTHOR]

Groundwater irrigation and energy played an important role in increasing agricultural production and food security in India; however, declining groundwater levels result in an increase of energy consumption and CO emission for lifting water. This, in the future, is expected to influence groundwater development and usage policy in India. This study was undertaken to assess the CO emission from groundwater irrigation in an agriculturally dominant district, Karnal of Haryana in India, and to explore the possibility of reducing CO emission through various management alternatives. This study indicates that the CO emission from groundwater irrigation for baseline scenario is the highest for sugarcane (93 kgCO/ha/m) followed by rice (40 kgCO/ha/m), wheat (28 kgCO/ha/m), mustard (26 kgCO/ha/m), pigeon pea (14 kgCO/ha/m) and pearl millet (4 kgCO/ha/m). However, on a district level, the total CO emission under the baseline scenario is highest for rice (140,655 Mt) followed by wheat (98,153 Mt) and sugarcane (18,416 Mt). Higher CO emissions from rice and wheat are due to more area under these crops. Results also indicate that CO emission can be reduced by 32 % by improving pump efficiency from 34.7 to 51 %. Results show that by improving irrigation efficiency in rice by 15 % and in other crops by 20 % over the baseline efficiency, CO emissions can be reduced by 23 % in rice and 25 % in other crops. By improving the pump set and irrigation efficiencies together up to the achievable level, CO emissions can be reduced up to 48 % for rice and other crops. [ABSTRACT FROM AUTHOR]

Responsibility for climate change lies at the heart of societal debate over actions to address it. The United Nations Framework Convention on Climate Change established the principle of 'common but differentiated responsibilities' among nations, suggesting that industrialized nations that had produced the greatest share of historic emissions bore particular responsibility for preventing dangerous interference with the climate system. But climate responsibilities can be attributed in other ways as well. Here, we explore the conceptual territory of responsibility. We consider the distinctive responsibilities of the major investor-owned producers of fossil fuels, assessing the actions these companies took and could have taken to act upon the scientific evidence of climate change. We conclude that major investor-owned fossil energy companies carry significant responsibility for climate change. It is still possible for these companies to effectively contribute to a solution. Significant progress in reducing emissions and limiting climate change could be achieved if companies 1) unequivocally communicate to the public, shareholders, and policymakers the climate risks resulting from continued use of their products, and therefore the need for restrictions on greenhouse gas emissions consistent with the 2 °C global temperature target; 2) firmly reject contrary claims by industry trade associations and lobbying groups; and, 3) accelerate their transition to the production of low-carbon energy. Evidence from history strongly suggests that a heightened societal focus on their climate responsibilities will be needed to hasten such a transition. [ABSTRACT FROM AUTHOR]

The UK has committed to reduce greenhouse gas (GHG) emissions by 80 % relative to 1990 levels by 2050, and it has been suggested that this should include a 70 % reduction in emissions from food. Meeting this target is likely to require significant changes to diets, but the likely effect of these changes on population nutritional intakes is currently unknown. However, the current average UK diets for men and women do not conform to WHO dietary recommendations, and this presents an opportunity to improve the nutritional content of diets while also reducing the associated GHG emissions. The results of this study show that if, in the first instance, average diets among UK adults conformed to WHO recommendations, their associated GHG emissions would be reduced by 17 %. Further GHG emission reductions of around 40 % could be achieved by making realistic modifications to diets so that they contain fewer animal products and processed snacks and more fruit, vegetables and cereals. However, our models show that reducing emissions beyond 40 % through dietary changes alone will be unlikely without radically changing current consumption patterns and potentially reducing the nutritional quality of diets. [ABSTRACT FROM AUTHOR]

Carbon dioxide removal (CDR) is the only geoengineering technique that allows negative emissions and the reduction of anthropogenic carbon in the atmosphere. Since the time scales of the global carbon cycle are largely driven by the exchanges with the natural oceanic stocks, the implementation of CDR actions is anticipated to create outgassing from the ocean that may reduce their efficiency. The adjustment of the natural carbon cycle to CDR was studied with a numerical Earth System Model, focusing on the oceanic component and considering two idealized families of CDR policies, one based on a target atmospheric concentration and one based on planned negative emissions. Results show that both actions are anticipated to release the anthropogenic carbon stored in the surface ocean, effectively increasing the required removal effort. The additional negative emissions are expected to be lower when the CDR policy is driven by planned removal rates without prescribing a target atmospheric CO concentration. [ABSTRACT FROM AUTHOR]

Establishing parkland agroforestry on currently treeless cropland in the West African Sahel may help mitigate climate change. To evaluate its potential, we used climatically suitable ranges for parklands for 19 climate scenarios, derived by ecological niche modeling, for estimating potential carbon stocks in parkland and treeless cropland. A biocarbon business model was used to evaluate profitability of hypothetical Terrestrial Carbon Projects (TCPs), across a range of farm sizes, farm numbers, carbon prices and benefit sharing mechanisms. Using climate analogues, we explored potential climate change trajectories for selected locations. If mature parklands covered their maximum range, carbon stocks in Sahelian productive land would be about 1,284 Tg, compared to 725 Tg in a treeless scenario. Due to slow increase rates of total system carbon by 0.4 Mg C ha a, most TCPs at carbon prices that seem realistic today were not feasible, or required the participation of large numbers of farmers. For small farms, few TCP scenarios were feasible, and low Net Present Values for farmers made it unlikely that carbon payments would motivate many to participate in TCPs, unless additional benefits were provided. Climate analogue locations indicated an uncertain climate trajectory for the Sahel, but most scenarios projected increasing aridity and reduced suitability for parklands. The potentially severe impacts of climate change on Sahelian ecosystems and the uncertain profitability of TCPs make the Sahel highly risky for carbon investments. Given the likelihood of degrading environmental conditions, the search for appropriate adaptation strategies should take precedence over promoting mitigation activities. [ABSTRACT FROM AUTHOR]

Climate data suggest greater warming over the Arctic than lower latitudes, and the most abundant direct source of black carbon and other climate-relevant pollutants over the Arctic is cross-polar flights by international aviation. A relevant question is whether rerouting cross-polar flights to circumnavigate the Arctic Circle reduces or enhances such warming. To study this issue, a model accounting for subgrid exhaust plumes from each individual commercial flight worldwide was used with 2006 global aircraft emission inventories that treated cross-polar flights and flights rerouted around the Arctic Circle (66.56083 °N), respectively. Rerouting increased fuel use by 0.056 % in the global average, mostly right outside the Arctic Circle, but most of the associated black carbon and other emissions were removed faster because they were now over latitudes of greater precipitation and lesser stability. Rerouting also reduced fuel use and emissions within the Arctic Circle by 83 % and delayed pollutant transport to the Arctic. The Arctic reduction in pollutants, particularly of black carbon, decreased Arctic and global temperature and increased Arctic sea ice over 22 years. Although the slight increase in total CO emissions due to rerouting may dampen the benefit of rerouting over more decades, rerouting or even partial rerouting (allowing cross-polar flights during polar night only) may delay the elimination of Arctic sea ice, which will otherwise likely occur within the next 2-3 decades due to global warming in general. Rerouting may increase worldwide fuel plus operational costs by only ~$99 million/yr, 47-55 times less than an estimated 2025 U.S.-alone cost savings due to the global warming reduction from rerouting. [ABSTRACT FROM AUTHOR]

Drought is one of the most devastating natural hazards faced by the Southern United States (SUS). Drought events and their adverse impacts on the economy, society and environment have been extensively reported during 1895-2007. Our aim is thus to characterize drought conditions in the SUS and explore the impacts on terrestrial ecosystem function (i.e., net primary productivity (NPP) and net carbon exchange (NCE)). Standard precipitation index (SPI) was used to characterize drought intensity and duration, and a process-based ecosystem model was used to explore the relationship between drought and ecosystem function. Combining overall information on growing-season SPI, drought area and duration, we concluded there was no significant change in drought conditions for the SUS during 1895-2007. However, increased drought intensity was found for many areas in the east, resulting in significant decreases in NPP for these areas, with the largest decrease up to 40% during extreme droughts. Changes in precipitation patterns increased C emissions of 0.16 Pg (1 Pg = 10 g) in the SUS during 1895-2007. The west (dry region) acted as a C sink due to increased precipitation, while the east (water-rich region) acted as a C source due to increased drought intensity. Both NPP and NCE significantly increased along a gradient of declining drought intensity. Changes in precipitation resulted in C sources in forest, wetland, and cropland ecosystems, while C sinks in shrubland and grassland ecosystems. Changes in air temperature could either enhance or reduce drought impacts on NPP and NCE across different vegetation types. [ABSTRACT FROM AUTHOR]

We explore allowable leakage for carbon capture and geological storage to be consistent with maximum global warming targets of 2.5 and 3 °C by 2100. Given plausible fossil fuel use and carbon capture and storage scenarios, and based on modeling of time-dependent leakage of CO, we employ a climate model to calculate the long-term temperature response of CO emissions. We assume that half of the stored CO is permanently trapped by fast mechanisms. If 40 % of global CO emissions are stored in the second half of this century, the temperature effect of escaped CO is too small to compromise a 2.5 °C target. If 80 % of CO is captured, escaped CO must peak 300 years or later for consistency with this climate target. Due to much more CO stored for the 3 than the 2.5 °C target, quality of storage becomes more important. Thus for the 3 °C target escaped CO must peak 400 years or later in the 40 % scenario, and 3000 years or later in the 80 % scenario. Consequently CO escaped from geological storage can compromise the less stringent 3 °C target in the long-run if most of global CO emissions have been stored. If less CO is stored only a very high escape scenario can compromise the more stringent 2.5 °C target. For the two remaining combinations of storage scenarios and climate targets, leakage must be high to compromise these climate targets. [ABSTRACT FROM AUTHOR]

The study aims to reveal Australian households' perceptions of climate change and their preferences for mitigation action. A web-based survey was conducted in November 2008 in which over 600 households from the state of New South Wales were asked for their willingness to bear extra household expenditure to support the 'Carbon Pollution Reduction Scheme', an emissions trading scheme proposed by the Australian government. The results of the study can be summarized in four key findings. First, respondents' willingness to pay for climate change mitigation is significantly influenced by their beliefs of future temperature rise. Support for the policy increased at a decreasing rate as the perceived temperature change rose. Second, perceptions of policy failure have a significant negative impact on respondents' support for the proposed mitigation measure. The higher the perceived likelihood that the measure would not deliver any outcome, the lower was the likelihood that respondents would support the policy. Third, respondent preferences for the proposed policy are influenced by the possibility of reaching a global agreement on emissions reduction. Sample respondents stated significantly higher values for the policy when the biggest polluting countries implement a similar scheme. Finally, respondents' willingness to take action against climate change, both at the national and household level, is found to be influenced by their level of mass-media exposure. Particularly, those respondents who watched 'An Inconvenient Truth' were significantly more likely to act for climate change mitigation than others. [ABSTRACT FROM AUTHOR]

Climate geoengineering proposals seek to rectify the current radiative imbalance via either (1) reducing incoming solar radiation (solar radiation management) or (2) removing CO from the atmosphere and transferring it to long-lived reservoirs (carbon dioxide removal). For each option, we discuss its effectiveness and potential side effects, also considering lifetime of effect, development and deployment timescale, reversibility, and failure risks. We present a detailed review that builds on earlier work by including the most recent literature, and is more extensive than previous comparative frameworks. Solar radiation management propsals are most effective but short-lived, whilst carbon dioxide removal measures gain effectiveness the longer they are pursued. Solar radiation management could restore the global radiative balance, but must be maintained to avoid abrupt warming, meanwhile ocean acidification and residual regional climate changes would still occur. Carbon dioxide removal involves less risk, and offers a way to return to a pre-industrial CO level and climate on a millennial timescale, but is potentially limited by the CO storage capacity of geological reservoirs. Geoengineering could complement mitigation, but it is not an alternative to it. We expand on the possible combinations of mitigation, carbon dioxide removal and solar radiation management that might be used to avoid dangerous climate change. [ABSTRACT FROM AUTHOR]

Anthropogenic greenhouse gas emissions are changing the Earth's climate and impose substantial risks for current and future generations. What are scientifically sound, economically viable, and ethically defendable strategies to manage these climate risks? Ratified international agreements call for a reduction of greenhouse gas emissions to avoid dangerous anthropogenic interference with the climate system. Recent proposals, however, call for a different approach: to geoengineer climate by injecting aerosol precursors into the stratosphere. Published economic studies typically neglect the risks of aerosol geoengineering due to (i) the potential for a failure to sustain the aerosol forcing and (ii) the negative impacts associated with the aerosol forcing. Here we use a simple integrated assessment model of climate change to analyze potential economic impacts of aerosol geoengineering strategies over a wide range of uncertain parameters such as climate sensitivity, the economic damages due to climate change, and the economic damages due to aerosol geoengineering forcing. The simplicity of the model provides the advantages of parsimony and transparency, but it also imposes severe caveats on the interpretation of the results. For example, the analysis is based on a globally aggregated model and is hence silent on intragenerational distribution of costs and benefits. In addition, the analysis neglects the effects of learning and has a very simplistic representation of climate change impacts. Our analysis suggests three main conclusions. First, substituting aerosol geoengineering for CO abatement can be an economically ineffective strategy. One key to this finding is that a failure to sustain the aerosol forcing can lead to sizeable and abrupt climatic changes. The monetary damages due to such a discontinuous aerosol geoengineering can dominate the cost-benefit analysis because the monetary damages of climate change are expected to increase with the rate of change. Second, the relative contribution of aerosol geoengineering to an economically optimal portfolio hinges critically on, thus far, deeply uncertain estimates of the damages due to aerosol forcing. Even if we assume that aerosol forcing could be deployed continuously, the aerosol geoengineering does not considerably displace CO abatement in the simple economic optimal growth model until the damages due to the aerosol forcing are rather low. Third, substituting aerosol geoengineering for greenhouse gas emission abatement can fail an ethical test regarding intergenerational justice. Substituting aerosol geoengineering for greenhouse gas emissions abatements constitutes a conscious risk transfer to future generations, in violation of principles of intergenerational justice which demands that present generations should not create benefits for themselves in exchange for burdens on future generations. [ABSTRACT FROM AUTHOR]

While remote sensing is able to provide spatially explicit datasets at regional to global scales, extensive application to date has been found only in the reporting and verification of ecosystem carbon fluxes under the Kyoto Protocol. One of the problems is that new remote sensing datasets can be used only with models or data assimilation schemes adapted to include a data input interface dedicated to the type and format of these remote sensing datasets. In this study, soil water index data (SWI), derived from the ERS scatterometer (10-daily time period with a spatial resolution of 50 km), are integrated into the ecosystem carbon balance model C-Fix to assess 10-daily Net Ecosystem Productivity (NEP) patterns of Europe from the remote sensing perspective on an approximate 1-by-1 km pixel scale using NDVI-AVHRR data. The modeling performance of NEP obtained with and without the assimilation of remotely sensed soil moisture data in the carbon flux model C-Fix is evaluated with EUROFLUX data. Results show a general decrease of the RRMSE of up to 11 with an average of 3.46. C-Fix is applied at the European scale to demonstrate the potential of this ecosystem carbon flux model, based on remote sensing inputs. More specifically, the strong impact of soil moisture on the European carbon balance in the context of the Kyoto Protocol (anthropogenic carbon emissions) is indicated at the country level. Results suggest that several European countries shift from being a carbon sink (i.e., NEP > 1) to being a carbon source (i.e., NEP < 0) whether or not short-term water availability (i.e., soil moisture) is considered in C-Fix NEP estimations. [ABSTRACT FROM AUTHOR]

The greenhouse gas inventory of the European Communities and its estimation of the uncertainty is built from 15 individual and independent greenhouse gas inventories. This presents a particular challenge and is possible only if homogeneous information is available for all member states and if a proper evaluation of correlation between member states is performed. To this end, we present a methodology that estimates a quantitative measure for the aggregated Tier-level as well as the uncertainty for the main categories in the agriculture sector. In contrast to the approach suggested in the IPCC guidelines, which uses uncertainty estimates for activity data and emissions factors for each source category, the method presented uses quantitative information from individual parameters used in the inventory calculations, in combination with a well defined procedure to aggregate the information. Not surprisingly, NO emissions from agricultural soils are found to dominate the uncertainty. The results demonstrate the importance of correlation, if uncertainties are combined for the whole of Europe. The biggest challenge seems to be to conceptually harmonize the uncertainty estimates for the activity data (which tend to be underestimated) and emission factors (which tend to be overestimated). [ABSTRACT FROM AUTHOR]