What are robust strategies in the face of uncertain climate threshold responses?

We use an integrated assessment model of climate change to analyze how alternative decision-making criteria affect preferred investments into greenhouse gas mitigation, the distribution of outcomes, the robustness of the strategies, and the economic value of information. We define robustness as trading a small decrease in a strategy’s expected performance for a significant increase in a strategy’s performance in the worst cases. Specifically, we modify the Dynamic Integrated model of Climate and the Economy (DICE-07) to include a simple representation of a climate threshold response, parametric uncertainty, structural uncertainty, learning, and different decision-making criteria. Economic analyses of climate change strategies typically adopt the expected utility maximization (EUM) framework. We compare EUM with two decision criteria adopted from the finance literature, namely Limited Degree of Confidence (LDC) and Safety First (SF). Both criteria increase the relative weight of the performance under the worst-case scenarios compared to EUM. We show that the LDC and SF criteria provide a computationally feasible foundation for identifying greenhouse gas mitigation strategies that may prove more robust than those identified by the EUM criterion. More robust strategies show higher near-term investments in emissions abatement. Reducing uncertainty has a higher economic value of information for the LDC and SF decision criteria than for EUM.     

What if negative emission technologies fail at scale? Implications of the Paris Agreement for big emitting nations

A cumulative emissions approach is increasingly used to inform mitigation policy. However, there are different interpretations of what ‘2°C’ implies. Here it is argued that cost-optimization models, commonly used to inform policy, typically underplay the urgency of 2°C mitigation. The alignment within many scenarios of optimistic assumptions on negative emissions technologies (NETs), with implausibly early peak emission dates and incremental short-term mitigation, delivers outcomes commensurate with 2°C commitments. In contrast, considering equity and socio-technical barriers to change, suggests a more challenging short-term agenda. To understand these different interpretations, short-term CO₂ trends of the largest CO₂ emitters, are assessed in relation to a constrained CO₂ budget, coupled with a ‘what if’ assumption that negative emissions technologies fail at scale. The outcomes raise profound questions around high-level framings of mitigation policy. The article concludes that applying even weak equity criteria, challenges the feasibility of maintaining a 50% chance of avoiding 2°C without urgent mitigation efforts in the short-term. This highlights a need for greater engagement with: (1) the equity dimension of the Paris Agreement, (2) the sensitivity of constrained carbon budgets to short-term trends and (3) the climate risks for society posed by an almost ubiquitous inclusion of NETs within 2°C scenarios.

POLICY RELEVANCE

Since the Paris meeting, there is increased awareness that most policy ‘solutions’ commensurate with 2°C include widespread deployment of negative emissions technologies (NETs). Yet much less is understood about that option’s feasibility, compared with near-term efforts to curb energy demand. Moreover, the many different ways in which key information is synthesized for policy makers, clouds the ability of policy makers to make informed decisions. This article presents an alternative approach to consider what the Paris Agreement implies, if NETs are unable to deliver more carbon sinks than sources. It illustrates the scale of the climate challenge for policy makers, particularly if the Agreement’s aim to address ‘equity’ is accounted for. Here it is argued that much more attention needs to be paid to what CO₂ reductions can be achieved in the short-term, rather than taking a risk that could render the Paris Agreement’s policy goals unachievable.     

Meeting the EU 2°C climate target: global and regional emission implications

Abstract

This article presents a set of multi-gas emission pathways for different CO₂-equivalent concentration stabilization levels, i.e. 400, 450, 500 and 550 ppm CO₂-equivalent, along with an analysis of their global and regional reduction implications and implied probability of achieving the EU climate target of 2°C. For achieving the 2°C target with a probability of more than 60%, greenhouse gas concentrations need to be stabilized at 450 ppm CO₂-equivalent or below, if the 90% uncertainty range for climate sensitivity is believed to be 1.5–4.5°C. A stabilization at 450 ppm CO₂-equivalent or below (400 ppm) requires global emissions to peak around 2015, followed by substantial overall reductions of as much as 25% (45% for 400 ppm) compared to 1990 levels in 2050. In 2020, Annex I emissions need to be approximately 15% (30%) below 1990 levels, and non-Annex I emissions also need to be reduced by 15–20% compared to their baseline emissions. A further delay in peaking of global emissions by 10 years doubles maximum reduction rates to about 5% per year, and very probably leads to high costs. In order to keep the option open of stabilizing at 400 and 450 ppm CO₂-equivalent, the USA and major advanced non-Annex I countries will have to participate in the reductions within the next 10–15 years.     

Assessing the probability of El Niño-related weather and climate anomalies in Russian regions

The risk and predictability of weather and climate anomalies in Russian regions associated with differen types of El Niño are estimated using long-term data (1891-2015) on surface air temperature, precipitation, and indices of drought and excessive moisture. The probability of anomalies of these parameters in spring and summer months is estimated for different phase transitions of El Niño events.     

Time to act now? Assessing the costs of delaying climate measures and benefits of early action

This paper compares the results of the three state of the art climate-energy-economy models IMACLIM-R, ReMIND-R, and WITCH to assess the costs of climate change mitigation in scenarios in which the implementation of a global climate agreement is delayed or major emitters decide to participate in the agreement at a later stage only. We find that for stabilizing atmospheric GHG concentrations at 450?ppm CO₂-only, postponing a global agreement to 2020 raises global mitigation costs by at least about half and a delay to 2030 renders ambitious climate targets infeasible to achieve. In the standard policy scenario??in which allocation of emission permits is aimed at equal per-capita levels in the year 2050??regions with above average emissions (such as the EU and the US alongside the rest of Annex-I countries) incur lower mitigation costs by taking early action, even if mitigation efforts in the rest of the world experience a delay. However, regions with low per-capita emissions which are net exporters of emission permits (such as India) can possibly benefit from higher future carbon prices resulting from a delay. We illustrate the economic mechanism behind these observations and analyze how (1) lock-in of carbon intensive infrastructure, (2) differences in global carbon prices, and (3) changes in reduction commitments resulting from delayed action influence mitigation costs.     

My country or my planet? Exploring the influence of multiple place attachments and ideological beliefs upon climate change attitudes and opinions

Research on people-place relations, specifically place attachment and place identity, is beginning to make an important contribution to understanding human responses to climate change. However, to date there has been a dearth of research on how place attachments at multiple scales, particularly the global, and individual level ideological beliefs combine to influence climate change attitudes and opinions. To address these gaps, survey data was collected from a representative sample of Australian citizens (N = 1147), capturing attachments at neighbourhood, city/town, state/territory, country and global scales, as well as a range of climate change belief and individual difference measures. Results show the importance of the interplay between national and global place attachments. Individuals expressing stronger global than national attachments were more likely to attribute climate change to anthropogenic causes, to oppose hierarchy-enhancing myths that legitimize climate inaction, and to perceive positive economic impacts arising from climate change responses, in comparison to individuals indicating stronger national over global place attachments. Individuals with stronger global than national attachments were more likely to be female, younger, and self-identify as having no religion, to be more likely to vote Green and to be characterized by significantly lower levels of right wing authoritarian and social dominance beliefs. Right wing authoritarian and social dominance beliefs mediated the effects of place attachments upon climate change skepticism. Explanations for the findings and implications for future research are discussed.     

Trends in precipitation parameters in the climate zones of southern Russia (1961–2011)

The data of 19 weather stations for 1961-2011 on total and maximum daily precipitation for the plain (<500 m above the sea level), foothill (500-1000 m), and mountain (1000-2000 m) zones of the south of European Russia are used for analyzing the precipitation regime, investigating its trends, revealing the extremes, and making conclusions on zonal seasonal and annual variations in precipitation.     

Enteric fermentation and ruminant eructation: the role (and control?) of methane in the climate change debate

Anthropogenic processes are responsible for between 55% and 70% of the estimated 600 Tg of methane that is released annually into the atmosphere, with enteric fermentation a major contributor to emissions in a number of countries. This paper therefore reviews current levels of CH₄ discharges by both animal type and country, and shows how the growth or decline in national herds over the last 20 years has significantly altered the global composition of enteric emissions. As developing countries are now responsible for almost three-quarters of such emissions, this has important implications in terms of mitigation strategies—particularly as such countries are presently outside the remit of the Kyoto Protocol.     

Messing with nature? Exploring public perceptions of geoengineering in the UK

Anthropogenic influence on the climate – and possible societal responses to it – offers a unique window through which to examine the way people think about and relate to the natural world. This paper reports data from four, one-day deliberative workshops conducted with members of the UK public during early 2012. The workshops focused on geoengineering – the deliberate, large-scale manipulation of the planetary environment – as one of three possible responses to climate change (alongside mitigation and adaptation). Here, we explore one of the most pervasive and wide-ranging themes to emerge from the workshops: whether geoengineering represented an unprecedented human intervention into ‘nature’, and what the moral consequences of this might be. Using the concept of ‘messing with nature’ as an analytical lens, we explore public perceptions of geoengineering. We also reflect on why ‘messing with nature’ was such a focal point for debate and disagreement, and whether the prospect of geoengineering may reveal new dimensions to the way that people think about the natural world, and their relationship to it.     

Pan evaporation and wind run decline in the Cape Floristic Region of South Africa (1974�C2005): implications for vegetation responses to climate change

In many regions of the world, increasing temperatures in recent decades are paradoxically associated with declining pan evaporation, but evidence is sparse for this trend from the southern hemisphere in general and sub-Saharan Africa in particular. In this study, we examined changes in pan evaporation and four other meteorological variables (rainfall, wind run, temperature and vapour pressure deficit) at 20 climate stations in the predominantly winter-rainfall Cape Floristic Region (CFR) of South Africa over the period 1974?C2005. Our results show that pan evaporation has declined significantly at 16 climate stations at an average rate of 9.1 mm a^???2 while wind run has declined significantly at all climate stations by more than 25% over the study period. Annual rainfall has not changed significantly at any of the climate stations while maximum temperature has increased significantly at all but one climate station at an average rate of 0.03°C a.^???1 over the study period. The trends in vapour pressure deficit are mixed and no clear regional pattern is evident. Our results raise important questions about the predicted catastrophic impact that the projected changes in twenty-first century climates will have on the rich flora of the region. If evaporative demand has declined over the last 30 years in the Cape Floristic Region then it is possible that more water has become available for plant growth, infiltration and runoff despite the widespread increase in temperature. However, decreased pan evaporation and wind run combined with increased temperatures could potentially reduce transpiration and exacerbate heat stress of plants on increasingly frequent hot and windless days during the summer drought. Contrary to other predictions for the area, it is also likely that the changing conditions will decrease the frequency and/or intensity of fires which are an important component of the ecology of the fire-adapted CFR. Consideration of other factors besides changes in temperature and rainfall are essential in debates on the impact of climate change on the vegetation of this region.     

Is it time to abolish company car benefits? An analysis of transport behaviour in Germany and implications for climate change

Company cars have received considerable attention because of their partial tax-exemption and the changes in travel behaviour they stimulate, including car model choices, distances driven, and car ownership patterns. This paper is the first to present evidence on actual transport behaviour change, based on mobility and fuel diaries, and comparing a sample of 624 company cars and 9328 private cars in Germany. Analysis confirms that company cars belong to the more heavily motorized car segments (with an average 97?kW, as opposed to 79?kW of private cars), and are driven more than private cars (24,672?km per year, compared to 12,828?km per year for private cars). Company car benefits also increase average household vehicle numbers by 25%. Results show that it is imperative to distinguish company cars of company owners relative to those driven by employees, as negative externalities increase significantly where company cars are used by the latter. Abolishing company car benefits could significantly reduce emissions from passenger road transport and stimulate change in the country’s automotive industries towards a lower-carbon path. As Germany is not currently on track to meet its climate mitigation targets, this would be a timely policy shift.

Key policy insights

• Company car benefits increase transport demand, car ownership, and average vehicle fleet engine power. These effects are particularly relevant for employees.

• Company cars have, in spite of their larger size and greater engine power, a (modestly) better fuel economy than private cars, possibly because they represent more recent and hence more efficient car models.

• A policy focus on vehicle fuel efficiency improvements will fail to reduce the German car fleet’s CO₂ emissions to a sustainable level.

• Abolishing company car benefits could yield a significant reduction in GHG emissions from passenger road transport.

• Company car subsidies are an out-dated mode of support for the fossil-fuel based automotive industry.

     

Influence of climate variability on land degradation (desertification) in the watershed of the upper Paraíba River

The study aimed to evaluate the influence of the rainfall and aridity index variability on the process of land degradation (desertification) in order to establish the current degree of increase or decrease in dryness in the watershed of the upper Paraíba River. It included all or part of 18 municipalities, distributed in the western and eastern Cariri regions of Paraíba state. The monthly average values of reference evapotranspiration according to Penman-Monteith method were applied in the annual hydrological balance for obtaining the annual time series of the aridity index for the period from 1950 to 2013. The Mann-Kendall test (MK) was used for trend identification in the annual time series of rainfall and aridity index, at a significance level of α = 0.05. The slope of the trends was obtained by Sen’s method, and the values of rainfall, aridity index, and statistics MK were spatially kriging, to generate thematic maps. The results indicate an increase in rainfall and reduced dryness in the watershed of the upper Paraíba River, conditions that do not contribute to trigger the process of land degradation (desertification), indicating that the cause of this environmental problem is not climatic. Thus, it can be suggested that the observed manifestations of land degradation (desertification) derive much of human than climatic actions. However, there is a trend of increasing dryness and reducing rainfall in the central portion of the watershed, with stronger core in the location of Camalaú. The spatial distribution of rainfall and aridity index shows that minimum values of rainfall coincide with maximum values of the aridity index. Higher values of rainfall were observed in the northwestern portion of the watershed, while the northeast and southeast portions had the lower rainfall values, with the strongest core in the locality of Cabaceiras. The eastern sector of the watershed has high dryness, unlike the western sector, rainier, with minimum values of dryness. In the western portion of the watershed, the aridity index was in the range considered semiarid, with moderate susceptibility to land degradation process. Similarly, in the eastern portion, the dryness stood in the range considered arid, with high susceptibility. The cores with more pronounced dryness correspond to the municipalities of Cabaceiras, Caraúbas, and São João do Cariri.     

Who and what are carbon markets for? Politics and the development of climate policy

Why have carbon markets been rapidly adopted as policy solutions to climate change in the last decade? Perhaps surprisingly, this question has attracted virtually no attention in the large literature on such markets. The standard arguments given for why carbon markets are good ways to respond to climate change do not explain why such markets have flourished as governance mechanisms in relation to climate. Carbon markets have spread and become taken-for-granted because of the potential they give to certain powerful actors (financiers, specifically) to create new cycles of investment, profits and growth. As a consequence, they make possible a political coalition combining financiers with environmentalists. This coalition has considerable potential to legitimize substantial cuts in carbon emissions in the face of continued opposition from other interests. It is the combination of these two elements – the promotion of specific growth sectors and the construction of a political coalition – that constitutes the principal political virtue of carbon markets. In order to demonstrate this claim, the history of emissions trading is traced and the implication of this analysis is explored for the further building of climate governance centred on carbon markets.     

Recent (1980–2009) evidence of climate change in the upper Karakoram, Pakistan

We investigate here recent (1980–2009) climate variability in the upper Karakoram, Northern Pakistan, of particular interest given the peculiar glacier behavior during the last two decades. Differently from other glacierized regions in the Hindu Kush–Karakoram–Himalaya region, glaciers in the Karakoram display limited ice thinning, and in some cases advancing has been detected. Climate analysis is required to describe recent (i.e., last three decades) variability, to aid highlighting of the factors driving glacier evolution. Starting from monthly data, we analyze seasonal values of total precipitation, number of wet days, maximum (max) and minimum (min) air temperature, max precipitation in 24 h, and cloud cover for 17 weather stations in the upper Karakoram, clustered within three climatic regions as per use of principal components analysis. We detect possible nonstationarity in each of these regions by way of (1) linear regression, (2) moving window average, and (3) Mann–Kendall test, also in progressive form, to detect the onset date of possible trends. We then evaluate linear correlation coefficients between Northern Atlantic Oscillation (NAO) index and climate variables to assess effectiveness of teleconnections, claimed recently to affect climate in this area. Also, we compare temperature within the investigated zone against global temperature anomalies, to evidence enhanced warming within this area. We found mostly nonsignificant changes of total precipitation, unless for few stations displaying increase in Chitral-Hindu Kush region and Northwest Karakoram, or Gilgit area, and decrease in Western Himalaya, Kotli region. Max precipitation is mostly unchanged, unless for slight increase in Chitral and Gilgit areas, and slight decrease in Kotli region. Number of wet days is mostly increasing in Gilgit area, and decreasing in Chitral area, with no clear signal in Kotli region. Min temperatures increase always but during Summer, when decreasing values are detected, especially for Gilgit and Chitral regions. Max temperatures are found to increase everywhere. Cloud cover is significantly increasing in Gilgit area, but decreasing otherwise, especially in Kotli region. Max temperature regime is significantly positively correlated against global thermal anomaly, while min temperature regime is nonsignificantly negatively correlated. Max and min temperatures seem mostly negatively correlated to NAO. Some dependence of trend intensity for the considered variables against altitude is found, different for each region, suggesting that investigation of weather variables at the highest altitudes is warranted to discriminate further climate variability in the area.     

Homogeneity assessment of a station climate series (1933–2005) in the Metropolitan Area of S?o Paulo: instruments change and urbanization effects

This work assessed homogeneity of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) weather station climate series, using various statistical techniques. The record from this target station is one of the longest in Brazil, having commenced in 1933 with observations of precipitation, and temperatures and other variables later in 1936. Thus, it is one of the few stations in Brazil with enough data for long-term climate variability and climate change studies. There is, however, a possibility that its data may have been contaminated by some artifacts over time. Admittedly, there was an intervention on the observations in 1958, with the replacement of instruments, for which the size of impact has not been yet evaluated. The station transformed in the course of time from rural to urban, and this may also have influenced homogeneity of the observations and makes the station less representative for climate studies over larger spatial scales. Homogeneity of the target station was assessed applying both absolute, or single station tests, and tests relatively to regional climate, in annual scale, regarding daily precipitation, relative humidity, maximum (TMax), minimum (TMin), and wet bulb temperatures. Among these quantities, only precipitation does not exhibit any inhomogeneity. A clear signal of change of instruments in 1958 was detected in the TMax and relative humidity data, the latter certainly because of its strong dependence on temperature. This signal is not very clear in TMin, but it presents non-climatic discontinuities around 1953 and around 1970. A significant homogeneity break is found around 1990 for TMax and wet bulb temperature. The discontinuities detected after 1958 may have been caused by urbanization, as the observed warming trend in the station is considerably greater than that corresponding to regional climate.