What is climate change scepticism? Examination of the concept using a mixed methods study of the UK public

The holding of doubts about climate change is often referred to as ‘scepticism’. However, there has been a lack of clarity in previous work as to what exactly this scepticism comprises. We integrate data obtained from discussion groups and a nationally representative survey, to interrogate and refine the concept of climate change scepticism with respect to the views of members of the public. We argue that two main types should be distinguished: epistemic scepticism, relating to doubts about the status of climate change as a scientific and physical phenomenon; and response scepticism, relating to doubts about the efficacy of action taken to address climate change. Whilst each type is independently associated by people themselves with climate change scepticism, we find that the latter is more strongly associated with a lack of concern about climate change. As such, additional effort should be directed towards addressing and engaging with people's doubts concerning attempts to address climate change.     

The ‘ultimate objective’ of the framework convention on climate change requires a new approach in climate change research

In the Framework Convention on Climate Change an ultimate objective is formulated that calls for stabilization of the concentrations of greenhouse gases in the atmosphere at a level that would allow ecosystems to adapt naturally, safeguard food supply and enable sustainable development to proceed in a sustainable manner. This paper addresses the possible contribution of science to translate this rather vague and ambiguous objective into more practicable terms. We propose a regionalized, risk-based six-step approach that couples an analysis of ecosystem vulnerability to the results of simulations of climate change. An ultimate objective level could be determined in terms of stabilized concentrations of greenhouse gases in the atmosphere. The level and timing of this stabilization would be determined by a political appreciation of associated risks for managed and unmanaged ecosystems. These risks would be assessed by region in an internationally coordinated scientific effort, followed by a global synthesis.     

Assessment of climate change impacts on the quantity and quality of a coastal catchment using a coupled groundwater–surface water model

The hydrology of coastal catchments is influenced by both sea level and climate. Hence, a comprehensive assessment of the impact of climate change on coastal catchments is a challenging task. In the present study, a coupled groundwater–surface water model is forced by dynamically downscaled results from a general circulation model. The effects on water quantity and quality of a relatively large lake used for water supply are analyzed. Although stream inflow to the lake is predicted to decrease during summer, the storage capacity of the lake is found to provide a sufficient buffer to support sustainable water abstraction in the future. On the other hand, seawater intrusion into the stream is found to be a significant threat to the water quality of the lake, possibly limiting its use for water supply and impacting the aquatic environment. Additionally, the results indicate that the nutrient load to the lake and adjacent coastal waters is likely to increase significantly, which will increase eutrophication and have negative effects on the surface water ecology. The hydrological impact assessment is based on only one climate change projection; nevertheless, the range of changes generated by other climate models indicates that the predicted results are a plausible realization of climate change impacts. The problems identified here are expected to be relevant for many coastal regimes, where the hydrology is determined by the interaction between saline and fresh groundwater and surface water systems.     

How much information is lost by using global-mean climate metrics? an example using the transport sector

Metrics are often used to compare the climate impacts of emissions from various sources, sectors or nations. These are usually based on global-mean input, and so there is the potential that important information on smaller scales is lost. Assuming a non-linear dependence of the climate impact on local surface temperature change, we explore the loss of information about regional variability that results from using global-mean input in the specific case of heterogeneous changes in ozone, methane and aerosol concentrations resulting from emissions from road traffic, aviation and shipping. Results from equilibrium simulations with two general circulation models are used. An alternative metric for capturing the regional climate impacts is investigated. We find that the application of a metric that is first calculated locally and then averaged globally captures a more complete and informative signal of climate impact than one that uses global-mean input. The loss of information when heterogeneity is ignored is largest in the case of aviation. Further investigation of the spatial distribution of temperature change indicates that although the pattern of temperature response does not closely match the pattern of the forcing, the forcing pattern still influences the response pattern on a hemispheric scale. When the short-lived transport forcing is superimposed on present-day anthropogenic CO₂ forcing, the heterogeneity in the temperature response to CO₂ dominates. This suggests that the importance of including regional climate impacts in global metrics depends on whether small sectors are considered in isolation or as part of the overall climate change.     

US agricultural sector analysis on pesticide externalities – the impact of climate change and a Pigovian tax

Residuals from agricultural pesticides threaten the environment and human health. Climate change alters these externalities because it affects pest pressure and pesticide application rates. This study examines damages from pesticide externalities in US agriculture under different climate projections and the effects of alternative regulations. We find divergent impacts of externality regulation and climate change on agricultural production in the US. A Pigovian tax on pesticide externalities generally increases crop production cost, but farm revenue improves because of increased commodity prices. Climate change generally decreases US farm revenue because production increases and prices fall. Results also show a heterogeneous effect of climate change on pest management intensities across major crops.     

High impact,low probability? An empirical analysis of risk in the economics of climate change

To what extent does economic analysis of climate change depend on low-probability, high-impact events? This question has received a great deal of attention lately, with the contention increasingly made that climate damage could be so large that societal willingness to pay to avoid extreme outcomes should overwhelm other seemingly important assumptions, notably on time preference. This paper provides an empirical examination of some key theoretical points, using a probabilistic integrated assessment model. New, fat-tailed distributions are inputted for key parameters representing climate sensitivity and economic costs. It is found that welfare estimates do strongly depend on tail risks, but for a set of plausible assumptions time preference can still matter.     

Counting only the hits? The risk of underestimating the costs of stringent climate policy

This paper warns against the risk of underestimating the costs—and the uncertainty about the costs—of achieving stringent stabilization targets. We argue that a straightforward review of integrated assessment models results produces biased estimates for the more ambitious climate objectives such as those compatible with the 2°C of the European Union and the G8. The magnitude and range of estimates are significantly reduced because only the most optimistic results are reported for such targets. We suggest a procedure that addresses this partiality. The results show highly variable costs for the most ambitious scenarios.     

Future frost risks in the Tohoku region of Japan under a warming climate—interpretation of regional diversity in terms of seasonal warming

Theoretical and Applied Climatology - We investigated future frost risks in the Tohoku Region of Japan under climate change. We focused on the processes governing regional variations in the future...     

Initialisation and predictability of the AMOC over the last 50 years in a climate model

The mechanisms involved in Atlantic meridional overturning circulation (AMOC) decadal variability and predictability over the last 50 years are analysed in the IPSL–CM5A–LR model using historical and initialised simulations. The initialisation procedure only uses nudging towards sea surface temperature anomalies with a physically based restoring coefficient. When compared to two independent AMOC reconstructions, both the historical and nudged ensemble simulations exhibit skill at reproducing AMOC variations from 1977 onwards, and in particular two maxima occurring respectively around 1978 and 1997. We argue that one source of skill is related to the large Mount Agung volcanic eruption starting in 1963, which reset an internal 20-year variability cycle in the North Atlantic in the model. This cycle involves the East Greenland Current intensity, and advection of active tracers along the subpolar gyre, which leads to an AMOC maximum around 15 years after the Mount Agung eruption. The 1997 maximum occurs approximately 20 years after the former one. The nudged simulations better reproduce this second maximum than the historical simulations. This is due to the initialisation of a cooling of the convection sites in the 1980s under the effect of a persistent North Atlantic oscillation (NAO) positive phase, a feature not captured in the historical simulations. Hence we argue that the 20-year cycle excited by the 1963 Mount Agung eruption together with the NAO forcing both contributed to the 1990s AMOC maximum. These results support the existence of a 20-year cycle in the North Atlantic in the observations. Hindcasts following the CMIP5 protocol are launched from a nudged simulation every 5 years for the 1960–2005 period. They exhibit significant correlation skill score as compared to an independent reconstruction of the AMOC from 4-year lead-time average. This encouraging result is accompanied by increased correlation skills in reproducing the observed 2-m air temperature in the bordering regions of the North Atlantic as compared to non-initialized simulations. To a lesser extent, predicted precipitation tends to correlate with the nudged simulation in the tropical Atlantic. We argue that this skill is due to the initialisation and predictability of the AMOC in the present prediction system. The mechanisms evidenced here support the idea of volcanic eruptions as a pacemaker for internal variability of the AMOC. Together with the existence of a 20-year cycle in the North Atlantic they propose a novel and complementary explanation for the AMOC variations over the last 50 years.     

Future projections of the surface heat and water budgets of the Mediterranean Sea in an ensemble of coupled atmosphere–ocean regional climate models

Within the CIRCE project “Climate change and Impact Research: the Mediterranean Environment”, an ensemble of high resolution coupled atmosphere–ocean regional climate models (AORCMs) are used to simulate the Mediterranean climate for the period 1950–2050. For the first time, realistic net surface air-sea fluxes are obtained. The sea surface temperature (SST) variability is consistent with the atmospheric forcing above it and oceanic constraints. The surface fluxes respond to external forcing under a warming climate and show an equivalent trend in all models. This study focuses on the present day and on the evolution of the heat and water budget over the Mediterranean Sea under the SRES-A1B scenario. On the contrary to previous studies, the net total heat budget is negative over the present period in all AORCMs and satisfies the heat closure budget controlled by a net positive heat gain at the strait of Gibraltar in the present climate. Under climate change scenario, some models predict a warming of the Mediterranean Sea from the ocean surface (positive net heat flux) in addition to the positive flux at the strait of Gibraltar for the 2021–2050 period. The shortwave and latent flux are increasing and the longwave and sensible fluxes are decreasing compared to the 1961–1990 period due to a reduction of the cloud cover and an increase in greenhouse gases (GHGs) and SSTs over the 2021–2050 period. The AORCMs provide a good estimates of the water budget with a drying of the region during the twenty-first century. For the ensemble mean, he decrease in precipitation and runoff is about 10 and 15% respectively and the increase in evaporation is much weaker, about 2% compared to the 1961–1990 period which confirm results obtained in recent studies. Despite a clear consistency in the trends and results between the models, this study also underlines important differences in the model set-ups, methodology and choices of some physical parameters inducing some difference in the various air-sea fluxes. An evaluation of the uncertainty sources and possible improvement for future generation of AORCMs highlights the importance of the parameterisation of the ocean albedo, rivers and cloud cover.     

Facilitating adaptation of biodiversity to climate change: a conceptual framework applied to the world’s largest Mediterranean-climate woodland

The importance of ecological management for reducing the vulnerability of biodiversity to climate change is increasingly recognized, yet frameworks to facilitate a structured approach to climate adaptation management are lacking. We developed a conceptual framework that can guide identification of climate change impacts and adaptive management options in a given region or biome. The framework focuses on potential points of early climate change impact, and organizes these along two main axes. First, it recognizes that climate change can act at a range of ecological scales. Secondly, it emphasizes that outcomes are dependent on two potentially interacting and countervailing forces: (1) changes to environmental parameters and ecological processes brought about by climate change, and (2) responses of component systems as determined by attributes of resistance and resilience. Through this structure, the framework draws together a broad range of ecological concepts, with a novel emphasis on attributes of resistance and resilience that can temper the response of species, ecosystems and landscapes to climate change. We applied the framework to the world’s largest remaining Mediterranean-climate woodland, the ‘Great Western Woodlands’ of south-western Australia. In this relatively intact region, maintaining inherent resistance and resilience by preventing anthropogenic degradation is of highest priority and lowest risk. Limited, higher risk options such as fire management, protection of refugia and translocation of adaptive genes may be justifiable under more extreme change, hence our capacity to predict the extent of change strongly impinges on such management decisions. These conclusions may contrast with similar analyses in degraded landscapes, where natural integrity is already compromised, and existing investment in restoration may facilitate experimentation with higher risk?options.     

Empirical calibration of climate policy using corporate solvency: a case study of the UK’s carbon price support

Emission reductions improve the chances that dangerous anthropogenic climate change will be averted, but could also cause some firms financial distress. Corporate failures, especially if they are unnecessary, add to the social cost of abatement. Social value can be permanently destroyed by the dissolution of organizational capital, deadweight losses paid to liquidators, and unemployment. This article proposes using measures of corporate solvency as an objective tool for policy makers to calibrate the optimal stringency of climate change policies, so that they can deliver the least loss of corporate solvency for a given level of emission reductions. They could also be used to determine the generosity of any compensation to address losses to corporate solvency. We demonstrate this approach using a case study of the UK’s Carbon Price Support (a carbon tax).

Key policy insights

• Solvency metrics could be used to empirically calibrate the optimal stringency of climate policies.

• An idealized solvency trajectory for firms affected by climate change policy would cause corporate solvency to initially decline – approaching but not exceeding ‘distressed’ levels – and then gradually improve to a new ‘steady state’ once the low-carbon transition had been achieved.

• In terms of the UK’s Carbon Price Support, corporate solvency of energy-intensive industries was found to be stable subsequent to its introduction. Therefore, the available evidence does not support its later weakening.

     

Distributive justice in global climate finance – Recipients’ climate vulnerability and the allocation of climate funds

The ‘climate justice’ lens is increasingly being used in framing discussions and debates on global climate finance. A variant of such justice – distributive justice – emphasises recipient countries’ vulnerability to be an important consideration in funding allocation. The extent to which this principle is pursued in practice has been of widespread and ongoing concerns. Empirical evidence in this regard however remains inadequate and methodologically weak. This research examined the effect of recipients’ climate vulnerability on the allocation of climate funds by controlling for other commonly-identified determinants. A dynamic panel regression method based on Generalised Method of Moments (GMM) was used on a longitudinal dataset, containing approved funds for more than 100,000 projects covering three areas of climate action (mitigation, adaptation, and overlap) in 133 countries over two decades (2000–2018). Findings indicated a non-significant effect of recipients’ vulnerability on mitigation funding, but significant positive effects on adaptation and overlap fundings. ‘Most vulnerable’ countries were likely to receive higher amounts of these two types of funding than the ‘least vulnerable’ countries. All these provided evidence of distributive justice. However, the relationship between vulnerability and funding was parabolic, suggesting ‘moderately vulnerable’ countries likely to receive more funding than the ‘most vulnerable’ countries. Whilst, for mitigation funding, this observation was not a reason for concern, for adaptation and overlap fundings this was not in complete harmony with distributive justice. Paradoxically, countries with better investment readiness were likely to receive more adaptation and overlap funds. In discordance with distributive justice, countries within the Sub-Saharan Africa and South Asia regions, despite their higher climatic vulnerabilities, were likely to receive significantly less adaptation and overlap fundings. Effects of vulnerability were persistent, and past funding had significant effects on current funding. These, coupled with the impact of readiness, suggested a probable Low Funding Trap for the world’s most vulnerable countries. The overarching conclusion is that, although positive changes have occurred since the 2015 Paris Agreement, considerable challenges to distributive justice remain. Significant data and methodological challenges encountered in the research and their implications are also discussed.     

Modelling the impacts of climate change on wheat yield and field water balance over the Murray�CDarling Basin in Australia

The study used a modelling approach to assess the potential impacts of likely climate change and increase in CO₂ concentration on the wheat growth and water balance in Murray?CDarling Basin in Australia. Impacts of individual changes in temperature, rainfall or CO₂ concentration as, well as the 2050 and 2070 climate change scenarios, were analysed. Along an E?CW transect, wheat yield at western sites (warmer and drier) was simulated to be more sensitive to temperature increase than that at eastern sites; along the S?CN transect, wheat yield at northern warmer sites was simulated to be more sensitive to temperature increase, within 1?C3°C temperature increase. Along the E?CW and S?CN transects, wheat at drier sites would benefit more from elevated [CO₂] than at wetter sites, but more sensitive to the decline in rainfall. The increase in temperature only did not have much impact on water balance. Elevated [CO₂] increased the drainage in all the sites, whilst rainfall reduction decreased evapotranspiration, runoff and drainage, especially at drier sites. In 2050, wheat yield would increase by 1?C10% under all climate change scenarios along the S?CN transect, except for the northernmost site (Dalby). Along the E?CW transect, the most obvious increase of wheat yields under all climate change scenarios occurred in cooler and wetter eastern sites (Yass and Young), with an average increase rate of 7%. The biggest loss occurred at the driest sites (Griffith and Swan Hill) under A1FI and B2 scenarios, ranging from ?5% to ?16%. In 2070, there would be an increased risk of yield loss in general, except for the cool and wet sites. Water use efficiency was simulated to increase at most of the study sites under all the climate change scenarios, except for the driest site. Yield variability would increase at drier sites (Ardlethan, Griffith and Swan Hill). Soil types would also impact on the response of wheat yield and water balance to future climate change.