CAPS facilitates filling of the rapidly releasable pool of large dense-core vesicles

Calcium-activator protein for secretion (CAPS) is a cytosolic protein that associates with large dense-core vesicles and is involved in their secretion. Mammals express two CAPS isoforms, which share a similar domain structure including a Munc13 homology domain that is believed to be involved in the priming of secretory vesicles. A variety of studies designed to perturb CAPS function indicate that CAPS is involved in the secretion of large dense-core vesicles, but where in the secretory pathway CAPS acts is still under debate. Mice in which one allele of the CAPS-1 gene is deleted exhibit a deficit in catecholamine secretion from chromaffin cells. We have examined catecholamine secretion from chromaffin cells in which both CAPS genes were deleted and show that the deletion of both CAPS isoforms causes a strong reduction in the pool of rapidly releasable chromaffin granules and of sustained release during ongoing stimulation. We conclude that CAPS is required for the adequate refilling and/or maintenance of a rapidly releasable granule pool

Aligning integrated assessment modelling with socio-technical transition insights: an application to low-carbon energy scenario analysis in Europe

In this study, we present and apply an interdisciplinary approach that systematically draws qualitative insights from socio-technical transition studies to develop new quantitative scenarios for integrated assessment modelling. We identify the transition narrative as an analytical bridge between socio-technical transition studies and integrated assessment modelling. Conceptual interaction is realised through the development of two contrasting transition narratives on the role of actors in meeting the European Unions' 80% greenhouse gas emission reduction objective for 2050. The first transition narrative outlines how large-scale innovation trajectories are driven by incumbent actors, whereas the second transition narrative assumes more ‘alternative’ strategies by new entrants with strong opposition to large-scale technologies. We use the multi-level perspective to draw out plausible storylines on actor positioning and momentum of change for several technological and social niche-innovations in both transition narratives. These storylines are then translated into quantitative scenarios for integrated assessment modelling. Although both developed transition pathways align with the European Union's low-carbon objective for 2050, we find that each pathway depicts a substantial departure from systems that are known to date. Future research could focus on further systematic (joint) development of operational links between the two analytical approaches, as well as work on improved representation of demand-oriented solutions in techno-economic modelling

Disutility of climate change damages warrants much stricter climate targets

Cost-benefit integrated assessment models (IAMs) inform the policy deliberation process by determining cost-optimal greenhouse gas emission reduction pathways based on economic considerations. These models seek to maximise economic utility and treat estimates of climate impacts (damages) and mitigation costs at par as GDP losses, having the same impact on utility reduction. However, prospect theory suggests that a certain level of climate damages could be valued higher by society than the same level of mitigation costs, as climate damages often occur as sudden unexpected events. In this paper, we show how this concept could be taken into account in cost-benefit IAMs and explore possible consequences on optimal mitigation pathways. Our results suggest that compared to the standard utility approach, capturing explicit aversion to climate impact incidence shows optimal pathways with earlier and deeper emission reduction, lowering both net-negative emissions and mid-century temperature peaks in line with stringent Paris Agreement targets

Disutility of climate change damages may warrant much stricter climate targets

Cost-benefit integrated assessment models (IAMs) inform the policy deliberation process by determining cost-optimal greenhouse gas emission reduction pathways based on economic considerations. These models seek to maximise economic utility and treat estimates of climate impacts (damages) and mitigation costs at par as GDP losses, having the same impact on utility reduction. However, prospect theory suggests that a certain level of climate damages could be valued higher by society than the same level of mitigation costs, as climate damages often occur as sudden unexpected events. In this paper, we show how this concept could be taken into account in cost-benefit IAMs and explore possible consequences on optimal mitigation pathways. Our results suggest that compared to the standard utility approach, capturing explicit aversion to climate impact incidence shows optimal pathways with earlier and deeper emission reduction, lowering both net-negative emissions and mid-century temperature peaks in line with stringent Paris Agreement targets

Economy-wide effects of coastal flooding due to sea level rise: A multi-model simultaneous treatment of mitigation, adaptation, and residual impacts

This article presents a multi-model assessment of the macroeconomic impacts of coastal flooding due to sea level rise and the respective economy-wide implications of adaptation measures for two greenhouse gas (GHG) concentration targets, namely the Representative Concentration Pathways (RCP)2.6 and RCP4.5, and subsequent temperature increases. We combine our analysis, focusing on the global level, as well as on individual G20 countries, with the corresponding stylized RCP mitigation efforts in order to understand the implications of interactions across mitigation, adaptation and sea level rise on a macroeconomic level. Our global results indicate that until the middle of this century, differences in macroeconomic impacts between the two climatic scenarios are small, but increase substantially towards the end of the century. Moreover, direct economic impacts can be partially absorbed by substitution effects in production processes and via international trade effects until 2050. By 2100 however, we find that this dynamic no longer holds and economy-wide effects become even larger than direct impacts. The disturbances of mitigation efforts to the overall economy may in some regions and for some scenarios lead to a counterintuitive result, namely to GDP losses that are higher in RCP26 than in RCP45, despite higher direct coastal damages in the latter scenario. Within the G20, our results indicate that China, India and Canada will experience the highest macroeconomic impacts, in line with the respective direct climatic impacts, with the two first large economies undertaking the highest mitigation efforts in a cost-efficient global climate action. A sensitivity analysis of varying socioeconomic assumptions highlights the role of climate-resilient development as a crucial complement to mitigation and adaptation efforts

Current lifestyles in the context of future climate targets: analysis of long-term scenarios and consumer segments for residential and transport

The carbon emissions of individuals strongly depend on their lifestyle, both between and within regions. Therefore, lifestyle changes could have a significant potential for climate change mitigation. This potential is not fully explored in long-term scenarios, as the representation of behaviour change and consumer heterogeneity in these scenarios is limited. We explore the impact and feasibility of lifestyle and behaviour changes in achieving climate targets by analysing current per-capita emissions of transport and residential sectors for different regions and consumer segments within one of the regions, namely Japan. We compare these static snapshots to changes in per-capita emissions from consumption and technology changes in long-term mitigation scenarios. The analysis shows less need for reliance on technological solutions if consumption patterns become more sustainable. Furthermore, a large share of Japanese consumers is characterised by consumption patterns consistent with those in scenarios that achieve ambitious climate targets, especially regarding transport. The varied lifestyles highlight the importance of representing consumer heterogeneity in models and further analyses

(Path)ways to sustainable living: The impact of the SLIM scenarios on long-term emissions

Sustainable lifestyles and behaviour changes can be vital in climate change mitigation. Various disciplines analyse the potential for such changes – but without much interaction. Qualitative studies look into the change process (e.g. social practice theory), while quantitative studies often focus on their impact in stylised cases (e.g. energy modelling). A more holistic approach can provide insightful scenarios with diverse lifestyle changes based on informed narratives for quantifying long-term impacts. This research explores how comprehensive sustainable lifestyle scenarios, coined SLIM (Sustainable Living in Models) scenarios, could contribute to transport and residential emission reductions. By translating and quantifying lifestyle scenario narratives through engagements with advisors and policymakers, we modelled two distinct lifestyle scenarios which differ in their degree of access to structural support. In one scenario, governments, corporations and cities leverage existing values and market systems to shape citizen and consumer preferences and everyday practices. In the other scenario, people adopt ambitious sustainable lifestyle behaviours and practices through peer-to-peer interaction and digital technology. We quantified the scenarios based on motivations, contextual factors, extent, and speed of lifestyle adoptions with regional differentiation. Furthermore, we applied heterogenous adopter groups to determine the model inputs. We present the resulting pathways in per capita emissions and more detailed changes in total emissions via decomposition analyses. We conclude that regional differentiation of the scenario narratives and modelling of intra-regional differences allows accounting for equity in lifestyle changes to a certain extent. Furthermore, new technologies are more important for enabling lifestyle change in a scenario with than a scenario without strong structural support. With strong structural support, lifestyle changes reduce transport and residential emissions to a larger degree (about 39% for Global North and 27% for Global South overall in 2050 relative to a “Middle-of-the-Road” SSP2 reference scenario in 2050). Thus, lifestyle changes in larger systems change are essential for effective climate change mitigation

A race to zero - Assessing the position of heavy industry in a global net-zero CO2 emissions context

In this study, we explore the decarbonisation pathways of four carbon and energy-intensive industries (respectively iron & steel, clinker & cement, chemicals and pulp & paper) in the context of a global 2050 net-zero carbon emissions objective using the IMAGE integrated assessment model. We systematically test the robustness of the model by studying its responses to four different decarbonisation narratives and across six different world regions. The study underpins earlier conclusions in the literature on ‘residual emissions’ and ‘hard-to-abate sectors’, such as the persistence of residual emissions and the overall continued use of fossil fuels by heavy industries within the global 2050 net-zero context (with the pulp & paper sector as an exception). However, under the condition that net-negative emissions are achieved in the power and energy conversion sectors prior to the 2050 landmark, the indirect emission removals can compensate for the residual emissions left in the industry sectors, rendering these sectors ‘net-zero’ as early as the 2040s. Full decarbonisation of industrial (sub)sector(s) is found to be possible, but only under very specific narratives and likely outside of the 2050 timeline for the iron & steel, clinker & cement and the chemical sector. Subsequently, we find that the decarbonisation patterns in IMAGE are industry and regionally specific, though, different strategic considerations (narratives) did not substantially change the models’ decarbonisation response before or after 2050. Important aspects of the decarbonisation responses are the (direct and indirect) electrification of the iron & steel sector, a full dependency on carbon removal technologies in the clinker & cement sector, the closing of carbon and material loops in the chemical sector and zero-carbon heating for the pulp & paper sector. However, further research and modelling efforts are needed to study a broader palette of conceivable decarbonisation pathways and implications for industry within a global 2050 net-zero economy context

Decomposition analysis of per capita emissions : a tool for assessing consumption changes and technology changes within scenarios

Recent studies show that behaviour changes can provide an essential contribution to achieving the Paris climate targets. Existing climate change mitigation scenarios primarily focus on technological change and underrepresent the possible contribution of behaviour change. This paper presents and applies a methodology to decompose the factors contributing to changes in per capita emissions in scenarios. With this approach, we determine the relative contribution to total emissions from changes in activity, the way activities are carried out, the intensity of activities, as well as fuel choice. The decomposition tool breaks down per capita emissions loosely following the Kaya Identity, allowing a comparison between the contributions of technology and consumption changes among regions and between various scenarios. We illustrate the use of the tool by applying it to three previously-published scenarios; a baseline scenario, a scenario with a selection of behaviour changes, and a 2 degrees C scenario with the same selection of behaviour changes. Within these scenarios, we explore the contribution of technology and consumption changes to total emission changes in the transport and residential sector, for a selection of both developed and developing regions. In doing so, the tool helps identify where specifically (i.e. via consumption or technology factors) different measures play a role in mitigating emissions and expose opportunities for improved representation of behaviour changes in integrated assessment models. This research shows the value of the decomposition tool and how the approach could be flexibly replicated for different global models based on available variables and aims. The application of the tool to previously-published scenarios shows substantial differences in consumption and technology changes from CO2 price and behaviour changes, in transport and residential per capita emissions and between developing and developed regions. Furthermore, the tool's application can highlight opportunities for future scenario development of a more nuanced and heterogeneous representation of behaviour and lifestyle changes in global models.Peer reviewe