CICERO Research Archive (CICERO Senter for klimaforskning)
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1083 research outputs found
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Coal transitions—part 2: phase-out dynamics in global long-term mitigation scenarios
Full text linkA rapid phase-out of unabated coal use is essential to limit global warming to below 2 °C. This review presents a comprehensive assessment of coal transitions in mitigation scenarios consistent with the Paris Agreement, using data from more than 1500 publicly available scenarios generated by more than 30 integrated assessment models. Our ensemble analysis uses clustering techniques to categorize coal transition pathways in models and bridges evidence on technological learning and innovation with historical data of energy systems. Six key findings emerge: First, we identify three archetypal coal transitions within Paris-consistent mitigation pathways. About 38% of scenarios are 'coal phase out' trajectories and rapidly reduce coal consumption to near zero. 'Coal persistence' pathways (42%) reduce coal consumption much more gradually and incompletely. The remaining 20% follow 'coal resurgence' pathways, characterized by increased coal consumption in the second half of the century. Second, coal persistence and resurgence archetypes rely on the widespread availability and rapid scale-up of carbon capture and storage technology (CCS). Third, coal-transition archetypes spread across all levels of climate policy ambition and scenario cycles, reflecting their dependence on model structures and assumptions. Fourth, most baseline scenarios—including the shared socio-economic pathways (SSPs)—show much higher coal dependency compared to historical observations over the last 60 years. Fifth, coal-transition scenarios consistently incorporate very optimistic assumptions about the cost and scalability of CCS technologies, while being pessimistic about the cost and scalability of renewable energy technologies. Sixth, evaluation against coal-dependent baseline scenarios suggests that many mitigation scenarios overestimate the technical difficulty and costs of coal phase-outs. To improve future research, we recommend using up-to-date cost data and evidence about innovation and diffusion dynamics of different groups of zero or low-carbon technologies. Revised SSP quantifications need to incorporate projected technology learning and consistent cost structures, while reflecting recent trends in coal consumption.publishedVersio
2023 temperatures reflect steady global warming and internal sea surface temperature variability
Full text link2023 was the warmest year on record, influenced by multiple warm ocean basins. This has prompted speculation of an acceleration in surface warming, or a stronger than expected influence from loss of aerosol induced cooling. Here we use a recent Green’s function-based method to quantify the influence of sea surface temperature patterns on the 2023 global temperature anomaly, and compare them to previous record warm years. We show that the strong deviation from recent warming trends is consistent with previously observed sea surface temperature influences, and regional forcing. This indicates that internal variability was a strong contributor to the exceptional 2023 temperature evolution, in combination with steady anthropogenic global warming.publishedVersio
Present-day methane shortwave absorption mutes surface warming relative to preindustrial conditions
Full text linkRecent analyses show the importance of methane shortwave absorption, which many climate models lack. In particular, Allen et al. (2023) used idealized climate model simulations to show that methane shortwave absorption mutes up to 30 % of the surface warming and 60 % of the precipitation increase associated with its longwave radiative effects. Here, we explicitly quantify the radiative and climate impacts due to shortwave absorption of the present-day methane perturbation. Our results corroborate the hypothesis that present-day methane shortwave absorption mutes the warming effects of longwave absorption. For example, the global mean cooling in response to the present-day methane shortwave absorption is K, which offsets 28 % (7 %–55 %) of the surface warming associated with present-day methane longwave radiative effects. The precipitation increase associated with the longwave radiative effects of the present-day methane perturbation (0.012±0.006 mm d−1) is also muted by shortwave absorption but not significantly so ( mm d−1). The unique responses to methane shortwave absorption are related to its negative top-of-the-atmosphere effective radiative forcing but positive atmospheric heating and in part to methane's distinctive vertical atmospheric solar heating profile. We also find that the present-day methane shortwave radiative effects, relative to its longwave radiative effects, are about 5 times larger than those under idealized carbon dioxide perturbations. Additional analyses show consistent but non-significant differences between the longwave versus shortwave radiative effects for both methane and carbon dioxide, including a stronger (negative) climate feedback when shortwave radiative effects are included (particularly for methane). We conclude by reiterating that methane remains a potent greenhouse gas.publishedVersio
Public support for aviation emission policies in India and Norway: Cross-country comparison
Full text linkWe examine public support for four policy instruments to reduce aviation emissions in India and Norway, analysing the determinants of support and the effect of information provision. Support is significantly higher in India, with coercive policies being the least popular. Perceived policy effectiveness and belief in anthropogenic climate change are strong predictors of support, whereas socio-economic predictors are largely insignificant. Respondents overestimate aviation’s CO2 emissions, with misperceptions affecting policy support. Providing factual information on aviation’s global emissions reduces support for jet fuel tax but not for other policies. Information about emissions from frequent flyers does not affect support levels. Findings highlight the influence of public perceptions and beliefs on policy support and suggest that while targeted information can modify attitudes, additional strategies are needed to boost support for aviation climate policies. Policymakers should note the public’s preference for proactive policies, indicating an opportunity to implement advanced, sustainable technologies.publishedVersio
Multi-model effective radiative forcing of the 2020 sulfur cap for shipping
Full text linkNew regulations of sulfur emissions from shipping were introduced in 2020, reducing emissions of SO2 from international shipping by ∼ 80 %. As SO2 is an aerosol precursor, this drop in emissions over the ocean will weaken the total aerosol effective radiative forcing (ERF) that has historically masked an uncertain fraction of the warming due to the increased concentration of greenhouse gases in the atmosphere. Here, we use four global climate models and a chemical transport model to calculate the ERF resulting from an 80 % reduction in SO2 emissions from international shipping relative to 2019 emission estimates. The individual model means range from 0.06 to 0.09 W m−2, corresponding to the ERF resulting from the increase in CO2 concentration over the last 2 to 3 years. The full uncertainty in the ERF due to the new regulation is not quantified but will very likely be high considering the contribution of uncertainties in shipping SO2 emissions, the sulfur cycle, the modelling of cloud adjustments and the impact of interannual variability on the method for calculating radiative forcing.publishedVersio
Transforming Aviation’s Impact on the Climate: Rethinking the Research Strategy
Full text linkAviation is under tremendous pressure to mitigate its impacts on the climate, but the best response strategies are unknown today due to deep uncertainties. How low-emission fuels will scale to levels relevant for the industry, along with the best strategies for managing contrails and other non-CO2 effects, are unknowable today with unknown cost and disruption. A conventional risk-based approach that involves investment across a known set of options is unworkable; instead, we argue that an experimentalist approach is needed that addresses deep uncertainties head on. This hinges on four key factors: a critical mass of actors facing strong incentives to identify solutions, a wide search for alternatives through experiments, periodic assessments, and adjustment of goals and strategies. Present strategies do not give enough attention to higher-risk alternatives with disruptive potential, because those approaches have few political and organizational supporters. Small groups of highly motivated actors─such as the nascent coalition of first movers on clean aviation already forming in Europe and the U.S.─could initiate an experimentalist program. The challenges of the aviation sector mirror other hard-to-abate sectors, making this framework potentially applicable to a wider set of sectors where technological, business, and investment choices are shrouded in deep uncertainty.acceptedVersio
Solar radiation modification challenges decarbonization with renewable solar energy
Full text linkSolar radiation modification (SRM) is increasingly being discussed as a potential tool to reduce global and regional temperatures to buy time for conventional carbon mitigation measures to take effect. However, most simulations to date assume SRM to be an additive component to the climate change toolbox, without any physical coupling between mitigation and SRM. In this study we analyze one aspect of this coupling: how renewable energy (RE) capacity, and therefore decarbonization rates, may be affected under SRM deployment by modification of photovoltaic (PV) and concentrated solar power (CSP) production potential. Simulated 1 h output from the Earth system model CNRM-ESM2-1 for scenario-based experiments is used for the assessment. The SRM scenario uses stratospheric aerosol injections (SAIs) to approximately lower global mean temperature from the high-emission scenario SSP585 baseline to the moderate-emission scenario SSP245. We find that by the end of the century, most regions experience an increased number of low PV and CSP energy weeks per year under SAI compared to SSP245. Compared to SSP585, while the increase in low energy weeks under SAI is still dominant on a global scale, certain areas may benefit from SAI and see fewer low PV or CSP energy weeks. A substantial part of the decrease in potential with SAI compared to the SSP scenarios is compensated for by optically thinner upper-tropospheric clouds under SAI, which allow more radiation to penetrate towards the surface. The largest relative reductions in PV potential are seen in the Northern and Southern Hemisphere midlatitudes. Our study suggests that using SAI to reduce high-end global warming to moderate global warming could pose increased challenges for meeting energy demand with solar renewable resources.publishedVersio
Lost in transaction?: An institutional analysis of households’ transaction costs from demand-side grid management
Full text linkBetter utilization of the electricity grid is urgently called for, and demand-side management (DSM) measures are implemented to influence consumers' electricity consumption to off-peak periods. Little is known about how DSM measures generate private transaction costs for households, being crucial for the effectiveness and fairness of such measures. This article contributes to the energy transition literature by exploring sources of private transaction costs for households from a time-of-use tariff scheme for the grid in Norway. Data from nine group interviews reveal that uncertainty about the transaction (grid capacity), distrust of the transactor (grid provider) and the complexity of the institutional context (uncertainty about the electricity sector) increase transaction costs for households and reduce effectiveness of the tariff. Providing households with information on the reasons and methods for adjusting electricity consumption is essential, including the economic impacts on households of the new tariff. Additionally, households should receive enhanced guidance of technology use and behavior changes. For these two steps to work, trust in energy actors must be strengthened. Lastly, one should pay attention to the potentially undermining effect of such DSM measures on legitimacy of energy policies in general, given the unequal levels of transaction costs depending on households’ capital.submittedVersio
Improving climate risk preparedness - Railroads in Norway
Full text linkClimate change affects all sectors of society due to changes in temperature and precipitation patterns and will continue to do so in the foreseeable future. Extreme weather events are already more frequent and intense, generating additional costs for businesses nationally and globally. Climate risk disclosure and management can be challenging due to the complexity of climate impacts and unpredictability of extreme events’ occurrence and location. To address the need for a systematic approach to manage physical climate change, this paper presents a ‘preparedness framework’ for a comprehensive physical climate risk assessment, which is inspired by the Task Force on Climate-related Financial Disclosures’ (TCFD) framework and based on interviews with representatives from the financial sector in Norway and Sweden on their management of climate risks. We analyze railroads in Norway as a case study due to the sector’s sensitivity to flooding events and heat stress. After assessing Bane NOR’s management of risk associated with flooding and heat stress, we discuss potential improvements regarding knowledge, strategy, management, and tools and metrics at a general level, emphasizing the benefits of improving capacity to handle climate change and the importance of contingency plans. The preparedness framework has helped identify strategies and actions that can reduce vulnerability to climate change impacts. We suggest that this checklist is sufficiently general to be applicable for other sectors and countries.publishedVersio
CICERO Simple Climate Model (CICERO-SCM v1.1.1) – an improved simple climate model with a parameter calibration tool
Full text linkThe CICERO Simple Climate Model (CICERO-SCM) is a lightweight, semi-empirical model of global climate. Here we present a new open-source Python port of the model for use in climate assessment and research. The new version of CICERO-SCM has the same scientific logic and functionality as the original Fortran version, but it is considerably more flexible and also open-source via GitHub. We describe the basic structure and improvements compared to the previous Fortran version, together with technical descriptions of the global thermal dynamics and carbon cycle components and the emission module, before presenting a range of standard figures demonstrating its application. A new parameter calibration tool is demonstrated to make an example calibrated parameter set to span and fit a simple target specification. CICERO-SCM is fully open-source and available through GitHubpublishedVersio