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Semi-arid regions are known for erratic precipitation patterns with significant effects on the hydrological cycle and water resources availability. High temporal and spatial variation in precipitation causes large variability in runoff over short durations. Due to low soil water storage capacity, base flow is often missing and rivers fall dry for long periods. Because of its climatic characteristics, the semi-arid north-eastern region of Brazil is prone to droughts. To counter these, reservoirs were built to ensure water supply during dry months. This paper describes problems and solutions when calibrating and validating the eco-hydrological model SWIM for semi-arid regions on the example of the Pajeú watershed in north-eastern Brazil. The model was calibrated to river discharge data before the year 1983, with no or little effects of water management, applying a simple and an enhanced approach. Uncertainties result mainly from the meteorological data and observed river discharges. After model calibration water management was included in the simulations. Observed and simulated reservoir volumes and river discharges are compared. The calibrated and validated models were used to simulate the impacts of climate change on hydrological processes and water resources management using data of two representative concentration pathways (RCP) and five earth system models (ESM). The differences in changes in natural and managed mean discharges are negligible (< 5%) under RCP8.5 but notable (> 5%) under RCP2.6 for the ESM ensemble mean. In semi-arid catchments, the enhanced approach should be preferred, because in addition to discharge, a second variable, here evapotranspiration, is considered for model validation. [ABSTRACT FROM AUTHOR]

In recent decades, greater acknowledgement has been given to climate change as a cultural phenomenon. This paper takes a cultural lens to the topic of climate change, in which climate-relevant understandings are grounded in wider cultural, political and material contexts. We approach climate-relevant accounts at the level of the everyday, understood as a theoretically problematic and politically contested space This is in contrast to simply being the backdrop to mundane, repetitive actions contributing to environmental degradation and the site of mitigative actions. Taking discourse as a form of practice in which fragments of cultural knowledge are drawn on to construct our environmental problems, we investigate citizens' accounts of climate-relevant issues in three culturally diverse emerging economies: Brazil, South Africa and China. These settings are important because greenhouse gas (GHG) emissions are predicted to significantly increase in these countries in the future. We conducted semi-structured interviews with a range of citizens in each country using a narrative approach to contextualise climate-relevant issues as part of people's lifestyle narratives. Participants overwhelmingly framed their accounts in the context of locally-salient issues, and few accounts explicitly referred to the phenomenon of climate change. Instead, elements of climate changes were conflated with other environmental issues and related to a wide range of cultural assumptions that influenced understandings and implied particular ways of responding to environmental problems. We conclude that climate change scholars should address locally relevant understandings and develop dialogues that can wider meanings that construct climate-relevant issues in vernacular ways at the local level. [ABSTRACT FROM AUTHOR]

Transitioning from a carbon-intensive development path to a low-carbon economy requires understanding of emission sources and its drivers. To achieve Nationally Determined Contribution targets discussed under the Paris Agreement, countries must project emission baselines considering different levels of ambition and sectoral performances and monitor government policies and mitigation actions. This study develops a Monitoring, Reporting, and Verification (MRV) framework based on energy use and carbon emission scenarios for Brazil up to 2030, focusing on transport. Three scenarios are developed based on different political commitments. All scenarios and mitigation actions are discussed under the Brazilian Forum on Climate Change, which is recognized as one of the most important institutional instruments of the National Policy on Climate Change. Results reveal a 41% abatement in CO2e emissions when comparing the most ambitious scenario to the conservative one. MRV framework indicates that Brazil is on track to a low carbon economic transition, although joint action is needed. This is mainly due to the increasing penetration of bioenergy into the transport energy matrix, while electromobility does not expand in Brazil at the pace of major international players such as Europe and China. Special contribution of this paper is on the role of bioenergy in prospective carbon emission scenarios, which is a lack in the literature. [ABSTRACT FROM AUTHOR]

This paper measures the influence of climate normals (average long-term surface wetness and temperature) and interannual climate variance on farms in the United States and Brazil using satellite data. The paper finds that just climate normals or just climate variance variables can explain both net revenues and how much land is used for cropland. However, because they are correlated with each other, it is important to include both normals and variance in the same statistical model to get accurate measures of their individual contribution to farm outcomes. In general, higher climate variance increases the probability that land is used for cropland in both countries and higher temperatures reduce both cropland and land values. Other annual effects were not consistent across the two countries. [ABSTRACT FROM AUTHOR]

This paper updates the SCVI (Socio-Climatic Vulnerability Index) maps developed by Torres et al. () for Brazil, by using the new Coupled Model Intercomparison Project Phase 5 (CMIP5) projections and more recent 2010 social indicators data. The updated maps differ significantly from their earlier versions in two main ways. First, they show that heavily populated metropolitan areas - namely Belo Horizonte, Brasília, Salvador, Manaus, Rio de Janeiro and São Paulo - and a large swath of land across the states of São Paulo, Minas Gerais and Bahia now have the highest SCVI values, that is, their populations are the most vulnerable to climate change in the country. Second, SCVI values for Northeast Brazil are considerably lower compared to the previous index version. An analysis of the causes of such difference reveals that changes in climate projections between CMIP3 and CMIP5 are responsible for most of the change between the different SCVI values and spatial distribution, while changes in social indicators have less influence, despite recent countrywide improvements in social indicators as a result of aggressive anti-poverty programs. These results raise the hypothesis that social reform alone may not be enough to decrease people's vulnerability to future climatic changes. Whereas the coarse spatial resolution and relatively simplistic formulation of the SCVI may limit how useful these maps are at informing decision-making at the local level, they can provide a valuable input for large-scale policies on climate change adaptation such as those of the Brazilian National Policy on Climate Change Adaptation. [ABSTRACT FROM AUTHOR]

Several studies show that the El Niño-Southern Oscillation (ENSO) is an important factor in determining interannual rainfall variability in South America. This signal is detected in the region including Northeastern Argentina, Uruguay and part of southern Brazil, in the form of excessive rains and big floods in the regional rivers. To check that this relationship was similar in the past the objectives of this paper were to construct a time series of large floods in the Paraná River region from documentary records, during the sixteenth to eighteenth centuries, and to evaluate the relationship between that historical record of extreme floods, the ENSO documentary evidence (Ortlieb, The Documented Historical Record of El Niño Events in Perú: An Update of the Quinn Record (Ortlieb, sixteenth through nineteenth centuries, Diaz and Markgraf, (eds.), El Niño and the southern oscillation. Multiscale variability and global and regional Impacts. Cambridge University Press, pp. 207-295, 2001; Quinn and Neal, The historical record of El Niño events, Bradley and Jones (eds.), Climate since a.d. 1500, Routledges, pp. 623-648, 1992) and the temperature index of the Pacific Ocean (Mann ME et al., Global temperature patterns in past centuries: an interactive presentation, IGBP pages/world data center for paleoclimatology data contribution series #2000-075. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA, 2000). Considering that the period 1904-2000, where 11 out of 16 floods occurred during El Niño events, it can be concluded that the proportion of years with exceptional flow volume in the Paraná River in years with El Niño events in the seventeenth and eighteenth centuries was relatively lower than that of the twentieth century. The reason for this difference is discussed. [ABSTRACT FROM AUTHOR]

We present an interdisciplinary review of the observed and projected variations in atmospheric and oceanic circulation within the southwestern South Atlantic focused on basin-scale processes driven by climate change, and their potential impact on the regional fisheries. The observed patterns of atmospheric circulation anomalies are consistent with anthropogenic climate change. There is strong scientific evidence suggesting that the Brazil Current is intensifying and shifting southwards during the past decades in response to changes in near-surface wind patterns, leading to intense ocean warming along the path of the Brazil Current, the South Brazil Bight, and in the Río de la Plata. These changes are presumably responsible for the poleward shift of commercially important pelagic species in the region and the long-term shift from cold-water to warm-water species in industrial fisheries of Uruguay. Scientific and traditional knowledge shows that climate change is also affecting small-scale fisheries. Long-term records suggest that mass mortalities decimated harvested clam populations along coastal ecosystems of the region, leading to prolonged shellfishery closures. More frequent and intense harmful algal blooms together with unfavorable environmental conditions driven by climate change stressors affect coastal shellfisheries, impact economic revenues, and damage the livelihood of local communities. We identify future modelling needs to reduce uncertainty in the expected effects of climate change on marine fisheries. However, the paucity of fisheries data prevents a more effective assessment of the impact of climate change on fisheries and hampers the ability of governments and communities to adapt to these changes. [ABSTRACT FROM AUTHOR]

The global food system is increasingly interconnected and under pressure to support growing demand. At the same time, crop production is facing new and uncertain impacts from climate change. To date, understanding how downstream supply chain actors, such as commodity traders, are exposed to climate change risks has been difficult due to a lack of high-resolution climate and trade data. However, the recent availability of supply chain data linking subnational production to downstream actors, and gridded projections of crop yield under climate change, allows us to assess individual commodity trader exposure to long-term climate change risk. We apply such an analysis to soy production in Brazil, the world's largest soy exporter. Whilst uncertainty across crop models' yield projections means it remains difficult to accurately predict how production across the region will be affected by climate change, we demonstrate that the risk exposure of trading actors differs substantially due to the heterogeneity in their sourcing. Our study offers a first attempt to analyze subnational climate risk to individual trading actors operating across an entire production landscape, leading to more precise risk exposure analysis. With sufficient subnational data, this method can be applied to any crop and country combination, and in the context of wider food security issues, it will be pertinent to apply these methods across other production systems and downstream actors in the food system. [ABSTRACT FROM AUTHOR]

Analyzing the politics and policy implications in Brazil of attributing extreme weather events to climate change, we argue for greater place-based sensitivity in recommendations for how to frame extreme weather events relative to climate change. Identifying geographical limits of current recommendations to emphasize the climate role in such events, we explore Brazilian framings of the two tragic national disasters, as apparent in newspaper coverage of climate change. We find that a variety of contextual factors compel environmental leaders and scientists in Brazil to avoid and discourage highlighting the role of climate change in national extreme events. Against analysts' general deficit-finding assumptions, we argue that the Brazilian framing tendency reflects sound strategic, socio-environmental reasoning, and discuss circumstances in which attributing such events to climate change—and, by extension, attribution science—can be ineffective for policy action on climate change and other socio-environmental issues in need of public pressure and preventive action. The case study has implications beyond Brazil by begging greater attention to policies and politics in particular places before assuming that attribution science and discursive emphasis on the climate role in extreme events are the most strategic means of achieving climate mitigation and disaster preparedness. Factors at play in Brazil might also structure extreme events attribution politics in other countries, not least some other countries of the global South. [ABSTRACT FROM AUTHOR]

The Intergovernmental Panel on Climate Change (IPCC) has put a lot of efforts to describe uncertainties and to judge the confidence level of its major conclusions. Despite a guidance to communicate uncertainty, the assignment of confidence is not sufficiently clear and, thus, hard to be reproduced by the extern community. By conducting a synthesis assessment about the impacts of climate change on the Brazilian water resources, we identified an opportunity to illustrate the characterization of evidence as adopted in IPCC reports. We propose a method to describe the evidence from model outputs wherein the quality and amount of studies, as well as the consistency among their conclusions, are subject of a transparent rating procedure. In summary, the more comprehensive the study in sampling uncertainties, the higher its quality. Likewise, the amount and consistency among conclusions is assigned in a systematic way. The method is applied for synthesizing a collection of 42 peer-reviewed articles. It reveals important aspects about the evidence of the potential impacts of climate change in the Brazilian water resources, such as changes into a drier hydrological regime. However, the use of multi-model ensemble, the evaluation of models, and the observational data is limited. The proposed method enables consistent communication of the degree of evidence in a transparent, traceable, and comprehensive fashion. The method can be used as a tool to support experts on their judgment. The approach is reproducible and can guide synthesis work not only in Brazil but anywhere else. [ABSTRACT FROM AUTHOR]

Coastal fishing communities are closely linked to the biological and ecological characteristics of exploited resources and the physical conditions associated with climate and ocean dynamics. Thus, the human populations that depend on fisheries are inherently exposed to climate variability and uncertainty. This study applied an ethno-oceanographic framework to investigate the perceptions of fishers on climate and ocean change to better understand the impacts of climate change on the coastal fishing communities of the South Brazil Bight. Seven coastal fishing communities that cover the regional diversity of the area were selected. Fishers were interviewed using a semi-structured questionnaire. The results suggest that fishers have detected climate-related changes in their environment such as reduced rainfall, increased drought events, calmer sea conditions, increases in air and ocean temperatures, changes in wind patterns and shoreline erosion. The perceptions of the fishers were compared to the available scientific data, and correlations were found with rainfall, wind speed and air and ocean temperatures. New hypotheses were raised based on the perceptions of fishers about sea level, coastal currents and sea conditions such as the hypothesis that the sea has become calmer. These perceived changes have positive and negative effects on the yields and livelihoods of fishers. The present work is the first evaluation of the perceptions of fishers on climate and ocean change and brings new understandings of climate-fishery-human interactions as well as provides inputs for future adaptation plans. [ABSTRACT FROM AUTHOR]

Hydropower generation plays a key role in mitigating GHG emissions from the overall power supply. Although the maximum achievable hydropower generation (MAHG) will be affected by climate change, it is seldom incorporated in integrated assessment models. In this study, we first used the H08 global hydrological model to project MAHG under two physical climate change scenarios. Then, we used the Asia-Pacific Integrated Model/Computable General Equilibrium integrated assessment model to quantify the economic consequences of the presence or absence of mitigation policy on hydropower generation. This approach enabled us to quantify the physical impacts of climate change and the effect of mitigation policy—together and in isolation—on hydropower generation and the economy, both globally and regionally. Although there was little overall global change, we observed substantial differences among regions in the MAHG average change (from − 71% in Middle East to 14% in Former Soviet Union in RCP8.5). We found that the magnitude of changes in regional gross domestic product (GDP) was small negative (positive) in Brazil (Canada) by 2100, for the no mitigation policy scenario. These consequences were intensified with the implementation of mitigation policies that enhanced the price competitiveness of hydropower against fossil fuel-powered technologies. Overall, our results suggested that there would be no notable globally aggregated impacts on GDP by 2100 because the positive effects in some regions were canceled out by negative effects in other regions. [ABSTRACT FROM AUTHOR]

To what extent citizens are willing not only to support ambitious climate policy but also willing to pay for such policy remains subject to debate. Our analysis addresses three issues in this regard: whether, as is widely assumed but not empirically established, willingness to support (WTS) is higher than willingness to pay (WTP); whether the determinants of the two are similar; and what accounts for within-subject similarity between WTS and WTP. We address these issues based on data from an original nationally representative survey ( N = 2500) on forest conservation in Brazil, arguably the key climate policy issue in the country. The findings reveal that WTP is much lower than WTS. The determinants differ to some extent as well, regarding the effects of age, gender, and trust in government. The analysis also provides insights into factors influencing how much WTS and WTP line up within individuals, with respect to age, education, political ideology, salience of the deforestation issue, and trust in government. Our findings provide a more nuanced picture of how strong public support for climate change policy is and a starting point for more targeted climate policy communication. [ABSTRACT FROM AUTHOR]

Reducing emissions from deforestation and degradation (REDD+) in tropical countries is an important and contested element of the post-Kyoto climate regime. For policy options which generate controversy between diverse actor groups, such as REDD+, mass media plays an important role in defining and supporting policy possibilities. Analysis of the way in which national media frames issues of climate change and deforestation can offer insights into the nature of the contested domains of the REDD+ policy process. Here, we examine the Brazilian national media discourses surrounding REDD+ because it contributes to setting the tone of policy debates at the federal level. Specifically, we ask the following: (i) How was REDD+ portrayed in the Brazilian national print media and whose opinions and perceptions were represented? and (ii) How have media frames on REDD+ in the national print media changed over time? Our results contribute with new knowledge for understanding the observed progress of REDD+ in Brazil. We identify two main themes that dominate the focus in the national media coverage of REDD+, specifically 'politics and policymaking' (representing half the coverage) and 'economics and market' (with over a third). Results show that discussions around carbon markets were amongst the most contested and that optimism in relation to REDD+ effectiveness declined over time. The analysis suggests that positions adopted on the national REDD+ strategy were shaped by state and federal collision of interests. We demonstrate an evolution of national concerns from an initial focus on efficiency (e.g. finance and carbon markets) to a recentred focus on equity issues (e.g. implementation of safeguards). We conclude with some thoughts on the implications of these features for REDD+ interventions and implementation in Brazil. [ABSTRACT FROM AUTHOR]

The latest scientific findings indicate that the increased concentration of greenhouse gases emitted by anthropogenic sources is significantly altering the balance of the global climate system. Considering forecasts of changes in the hydrological cycle and temperature related to global warming, the dynamics governing the functioning of the Pantanal Wetland, responsible for its rich biodiversity, find themselves threatened. Thus, this study was designed in the space-time of the Pantanal people called pantaneiros, and aims to discuss the Traditional Ecological Knowledge (TEK) of the Traditional Community Cuiabá Mirim regarding climate change. The information presented was obtained from 22 pantaneiros, between March 2008 and March 2010. The population sample was selected by the Snow Ball method. For data collection, semi structured interviews and oral histories were used. The results were compared with observations, simulations and projections of the IPCC AR4 for the region. The main findings of this research indicate that TEK presents itself as a crucial and complementary source of information for the development of local/regional adaptation strategies to climate change, bringing a distinct and relevant point of view from vulnerable stakeholders to the decision makers. [ABSTRACT FROM AUTHOR]

A regional vulnerability study in relation to the projected patterns of climate change (A2 and B2 scenarios) was developed for the Brazilian Northeastern region. An aggregated Vulnerability Index was constructed for each of the nine States of the region, based on the following information: population projections; climate-induced migration scenarios; disease trends; desertification rates; economic projections (GDP and employment) and projections for health care costs. The results obtained shall subsidize public policies for the protection of the human population from the projected impacts of regional changes in climate patterns. [ABSTRACT FROM AUTHOR]

Issues left undecided at COP-18 in Doha in December 2012 are critical to containing the two greatest threats to Brazil's Amazon forest: direct deforestation and forest loss through drought and fire provoked by climate change. Brazil's diplomatic positions on the role of tropical forests in mitigating global warming currently call for receiving donations through a voluntary fund, but without generating carbon credit valid against emissions-reduction commitments by countries that accept limits on their national emissions (i.e., Annex I countries). Brazil has long rejected accepting a target (assigned amount), and has instead presented a non-binding 'voluntary objective.' At COP-17 in Durban, Brazil expressed willingness to accept a commitment after 2020, but only if all of the rest of the world agreed to do the same. This author argues that Brazil's national interests would be better served by accepting a target now and by supporting fully marketable carbon credit from Reducing Emissions from Deforestation and Degradation (REDD). The global goal of preventing mean temperature from increasing beyond 2 °C above pre-industrial levels would be much more likely to be achieved in practice with tropical forests fully included in a carbon market as part of an agreement for the period after 2012. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of climate change on sugarcane yield, water use efficiency, and irrigation needs in southern Brazil, based on downscaled outputs of two general circulation models (PRECIS and CSIRO) and a sugarcane growth model. For three harvest cycles every year, the DSSAT/CANEGRO model was used to simulate the baseline and four future climate scenarios for stalk yield for the 2050s. The model was calibrated for the main cultivar currently grown in Brazil based on five field experiments under several soil and climate conditions. The sensitivity of simulated stalk fresh mass (SFM) to air temperature, CO concentration [CO] and rainfall was also analyzed. Simulated SFM responses to [CO], air temperature and rainfall variations were consistent with the literature. There were increases in simulated SFM and water usage efficiency (WUE) for all scenarios. On average, for the current sugarcane area in the State of São Paulo, SFM would increase 24 % and WUE 34 % for rainfed sugarcane. The WUE rise is relevant because of the current concern about water supply in southern Brazil. Considering the current technological improvement rate, projected yields for 2050 ranged from 96 to 129 t ha, which are respectively 15 and 59 % higher than the current state average yield. [ABSTRACT FROM AUTHOR]

This article reviews the exploration of the climate dynamics of Brazil's Nordeste in the course of a century. The drought-prone and semi-arid northern Nordeste of Brazil experiences a short rainy season around March-April, when the interhemispheric gradient of sea surface temperature (SST) in the tropical Atlantic is weakest and the Intertropical Convergence Zone (ITCZ) reaches its southernmost position in the course of the annual cycle. The recurrent Secas (droughts) have a severe socio-economic impact. During drought years, the interhemispheric SST gradient in the tropical Atlantic is steep and the ITCZ stays far North, while the waters of the eastern equatorial Pacific tend to be anomalously warm. Based on the extensive diagnostic exploration of the circulation mechanisms of interannual climate variability, empirical methods have been developed for the forecasting of the Nordeste rainy season. These have been applied in the real-time prediction of seasonal rainfall anomalies throughout the last decade of the 20th century. [ABSTRACT FROM AUTHOR]

Agriculture appears to be one of the human activities most vulnerable to climatic changes due to its large dependence on environmental conditions. However, the diversity of Brazilian environmental conditions could be of great advantage to adapting this sector to new climatic conditions, which should be assessed as in this study on shifting Arabica coffee cultivation to the extreme south of the country. The methodology applied is the same the one used to define climatic risks in current productive regions of Brazil and their vulnerability to climatic change predicted by IPCC reports. The basic climatic parameters applied were frost probability and annual average temperature, since annual water deficit did not prove to be a restricting factor for Arabica coffee cultivation in the study area. The climatic conditions suitable for coffee production are: annual average temperature between 18°C and 22°C, annual water deficit less than 100 mm and frost probability (risk of lowest annual temperature less than 1°C) less than 25%. An area is said to have 'low climatic risks' for coffee production when these three climatic conditions are met. Current climatic conditions were used and simulations of four temperature increases between 1°C and 4°C were also performed. The results indicated a substantial increase in the size of low climatic risks areas for the production of Arabica coffee in the extreme south of Brazil, mainly for mean temperature increases of 3°C in the study area in relation to present conditions. Increases of 2°C and 4°C were also favorable, but not as good as those obtained for 3°C. It should be underscored that areas with low climatic risks will be able to be found mainly in the extreme south of the study region, the border with Uruguay and North of Argentina. [ABSTRACT FROM AUTHOR]

Global biomass potentials are considerable but unequally distributed over the world. Countries with Kyoto targets could import biomass to substitute for fossil fuels or invest in bio-energy projects in the country of biomass origin and buy the credits (Clean Development Mechanism (CDM) and Joint Implementation (JI)). This study analyzes which of those options is optimal for transportation fuels and looks for the key variables that influence the result. In two case studies (Mozambique and Brazil), the two trading systems are compared for the amount of credits generated, land-use and associated costs. We found costs of 17–30 euro per ton of carbon for the Brazilian case and economic benefits of 11 to 60 euros per ton of carbon avoided in the Mozambique case. The impact of carbon changes related to direct land-use changes was found to be very significant (both positive and negative) and can currently only be included in emission credit trading, which can largely influence the results. In order to avoid indirect land-use changes (leakage) and consequent GHG emissions, it is crucial that bioenergy crop production is done in balance with improvements of management of agriculture and livestock management. Whatever trading option is economically most attractive depends mainly on the emission baseline in the exporting (emission credit trading) or importing (physical trading) country since both bio- and fossil fuel prices are world market prices in large scale trading systems where transportation costs are low. Physical trading could be preferential since besides the GHG reduction one could also benefit from the energy. It could also generate considerable income sources for exporting countries. This study could contribute to the development of a methodology to deal with bio fuels for transport, in Emission Trading (ET), CDM and the certification of traded bio fuels. [ABSTRACT FROM AUTHOR]

There is a growing understanding that energy services play a crucial role in underpinning efforts to achieve the UN Millennium Development Goals (MDG) and in improving the lives of poor people. Brazil remains challenged in regard to a number of social issues, notably poverty reduction in isolated areas, where access to electricity is as poor as their population. In the Amazonian region, most people have no access to electricity, or else have only a precarious supply. Due to several economic and technical reasons, many cities have old, inefficient diesel generators. In such a scenario, CDM (Clean Development Mechanism) can be an instrument both to mitigate climate change and to promote sustainable development in these remote areas, thereby contributing to the achievement of the MDGs in Brazil. However, CDM implementation in Brazil is still restricted to a few types of projects (such as sugar cane bagasse cogeneration and landfill gas use), mostly proposed by big companies and hardly ever directed to the Amazon region. The main objectives of this article are to assess the potential of CDM as a possible tool to promote electricity access to the poor rural population in the Amazonian region, and to discuss the main reasons why it has not become a reality so far. [ABSTRACT FROM AUTHOR]

Abstract The Brazilian Proposal for setting emission targets is based on attribution of responsibility for climate change due to historical emissions of greenhouse gases. Numerical models are used to calculate the temperature increase due to past emissions of greenhouse gases, and to partition the warming among nations or groups of nations. When non-linearities are included in the models, there are different approaches that can be used to partition global warming into regional or national contributions, and the methods give different results. Here we describe and compare seven different approaches for attributing indicators of climate change for regional emissions. We illustrate these methods with simple and realistic examples, and discuss their characteristics. Of the seven attribution methods discussed, two (the marginal and time-sliced methods) are seen as best-suited for attribution of climate change. Differences between attribution methods are typically up to a few percent for the examples considered, with differences greatest for regions with emission time histories that differ most from the average. The range due to choice of attribution method in the relative contributions of temperature change in 2000 is typically around one fifth of the range generated when other choices such as different models, forcing agents, feedbacks and other assumptions are included. [ABSTRACT FROM AUTHOR]