Imperial College London

MrNeil ScottGrant

Faculty of Natural SciencesThe Grantham Institute for Climate Change

Casual - Academic Professional
 
 
 
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n.grant18 Website

 
 
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C504Roderic Hill BuildingSouth Kensington Campus

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Summary

 

Publications

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11 results found

Grant N, Gambhir A, Mittal S, Greig C, Koberle ACet al., 2022, Enhancing the realism of decarbonisation scenarios with practicable regional constraints on CO<sub>2</sub> storage capacity, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 120, ISSN: 1750-5836

Journal article

van Soest HL, Aleluia Reis L, Baptista LB, Bertram C, Després J, Drouet L, den Elzen M, Fragkos P, Fricko O, Fujimori S, Grant N, Harmsen M, Iyer G, Keramidas K, Köberle AC, Kriegler E, Malik A, Mittal S, Oshiro K, Riahi K, Roelfsema M, van Ruijven B, Schaeffer R, Silva Herran D, Tavoni M, Unlu G, Vandyck T, van Vuuren DPet al., 2022, Author Correction: Global roll-out of comprehensive policy measures may aid in bridging emissions gap., Nature Communications, Vol: 13, Pages: 1-1, ISSN: 2041-1723

Journal article

Sognnaes I, Gambhir A, van de Ven D-J, Nikas A, Anger-Kraavi A, Bui H, Campagnolo L, Delpiazzo E, Doukas H, Giarola S, Grant N, Hawkes A, Köberle AC, Kolpakov A, Mittal S, Moreno J, Perdana S, Rogelj J, Vielle M, Peters GPet al., 2021, A multi-model analysis of long-term emissions and warming implications of current mitigation efforts, Nature Climate Change, Vol: 11, Pages: 1055-1062, ISSN: 1758-678X

Most of the integrated assessment modelling literature focuses on cost-effective pathways towards given temperature goals. Conversely, using seven diverse integrated assessment models, we project global energy CO2 emissions trajectories on the basis of near-term mitigation efforts and two assumptions on how these efforts continue post-2030. Despite finding a wide range of emissions by 2050, nearly all the scenarios have median warming of less than 3 °C in 2100. However, the most optimistic scenario is still insufficient to limit global warming to 2 °C. We furthermore highlight key modelling choices inherent to projecting where emissions are headed. First, emissions are more sensitive to the choice of integrated assessment model than to the assumed mitigation effort, highlighting the importance of heterogeneous model intercomparisons. Differences across models reflect diversity in baseline assumptions and impacts of near-term mitigation efforts. Second, the common practice of using economy-wide carbon prices to represent policy exaggerates carbon capture and storage use compared with explicitly modelling policies.

Journal article

van Soest HL, Aleluia Reis L, Baptista LB, Bertram C, Després J, Drouet L, den Elzen M, Fragkos P, Fricko O, Fujimori S, Grant N, Harmsen M, Iyer G, Keramidas K, Köberle AC, Kriegler E, Malik A, Mittal S, Oshiro K, Riahi K, Roelfsema M, van Ruijven B, Schaeffer R, Silva Herran D, Tavoni M, Unlu G, Vandyck T, van Vuuren DPet al., 2021, Global roll-out of comprehensive policy measures may aid in bridging emissions gap, Nature Communications, Vol: 12, ISSN: 2041-1723

Closing the emissions gap between Nationally Determined Contributions (NDCs) and the global emissions levels needed to achieve the Paris Agreement's climate goals will require a comprehensive package of policy measures. National and sectoral policies can help fill the gap, but success stories in one country cannot be automatically replicated in other countries. They need to be adapted to the local context. Here, we develop a new Bridge scenario based on nationally relevant, short-term measures informed by interactions with country experts. These good practice policies are rolled out globally between now and 2030 and combined with carbon pricing thereafter. We implement this scenario with an ensemble of global integrated assessment models. We show that the Bridge scenario closes two-thirds of the emissions gap between NDC and 2 °C scenarios by 2030 and enables a pathway in line with the 2 °C goal when combined with the necessary long-term changes, i.e. more comprehensive pricing measures after 2030. The Bridge scenario leads to a scale-up of renewable energy (reaching 52%-88% of global electricity supply by 2050), electrification of end-uses, efficiency improvements in energy demand sectors, and enhanced afforestation and reforestation. Our analysis suggests that early action via good-practice policies is less costly than a delay in global climate cooperation.

Journal article

Grant N, Hawkes A, Napp T, Gambhir Aet al., 2021, Cost reductions in renewables can substantially erode the value of carbon capture and storage in mitigation pathways, One Earth, Vol: 4, Pages: 1588-1601, ISSN: 2590-3322

Tackling climate change requires a rapid transition to net-zero energy systems. A variety of different technologies could contribute to this transition, and uncertainty remains over their relative role and value. A growing school of thought argues that rapid cost reductions in renewables reduce the need for carbon capture and storage (CCS) in mitigation pathways. Here we use an integrated assessment model to explore how the value of CCS is affected by cost reductions in solar photovoltaics, onshore, and offshore wind. Low-cost renewables could erode the value of CCS by 15%–96% across different energy sectors. Renewables directly compete with CCS, accelerate power sector decarbonization, and enable greater electrification of end-use sectors. CCS has greatest value and resilience to low-cost renewables in sustainable bioenergy/industrial applications, with limited value in hydrogen/electricity generation. This suggests that targeted, rather than blanket, CCS deployment represents the best strategy for achieving the Paris Agreement goals.

Journal article

Grant N, Hawkes A, Mittal S, Gambhir Aet al., 2021, The policy implications of an uncertain carbon dioxide removal potential, Joule, Vol: 5, Pages: 2593-2605, ISSN: 2542-4351

Many low-carbon scenarios rely on carbon dioxide removal (CDR) to meet decarbonization goals. The feasibility of large-scale CDR deployment is highly uncertain, and existing scenarios have been criticized for overreliance on CDR. We conduct an expert survey on the feasible potential for CDR via bioenergy with carbon capture and storage, direct air capture and afforestation. We use the survey results to represent uncertainty in future CDR availability and explore the implications in an integrated assessment model. Stochastic optimization demonstrates that uncertainty in future CDR availability provides a strong rationale to increase near-term rates of decarbonization. In scenarios with high CDR uncertainty, emissions are reduced by an additional 10 GtCO2e in 2030 compared with scenarios with no consideration of CDR uncertainty. This highlights the urgent need to increase ambition contained in nationally determined contributions (NDCs) for 2030, to get the world on track to deliver 1.5°C and to hedge against an uncertain future CDR potential.

Journal article

Giarola S, Mittal S, Vielle M, Perdana S, Campagnolo L, Delpiazzo E, Bui H, Anger Kraavi A, Kolpakov A, Sognnaes I, Peters G, Hawkes A, Koberle A, Grant N, Gambhir A, Nikas A, Doukas H, Moreno J, van de Ven D-Jet al., 2021, Challenges in the harmonisation of global integrated assessment models: a comprehensive methodology to reduce model response heterogeneity, Science of the Total Environment, Vol: 783, ISSN: 0048-9697

Harmonisation sets the ground to a solid inter-comparison of integrated assessment models. A clear and transparent harmonisation process promotes a consistent interpretation of the modelling outcomes divergences and, reducing the model variance, is instrumental to the use of integrated assessment models to support policy decision-making. Despite its crucial role for climate economic policies, the definition of a comprehensive harmonisation methodology for integrated assessment modelling remains an open challenge for the scientific community.This paper proposes a framework for a harmonisation methodology with the definition of indispensable steps and recommendations to overcome stumbling blocks in order to reduce the variance of the outcomes which depends on controllable modelling assumptions. The harmonisation approach of the PARIS REINFORCE project is presented here to layout such a framework. A decomposition analysis of the harmonisation process is shown through 6 integrated assessment models (GCAM, ICES-XPS, MUSE, E3ME, GEMINI-E3, and TIAM). Results prove the potentials of the proposed framework to reduce the model variance and present a powerful diagnostic tool to feedback on the quality of the harmonisation itself.

Journal article

Grant N, Hawkes A, Mittal S, Gambhir Aet al., 2021, Confronting mitigation deterrence in low-carbon scenarios, Environmental Research Letters, Vol: 16, ISSN: 1748-9326

Carbon dioxide removal (CDR) features heavily in low-carbon scenarios, where it often substitutes for emission reductions in both the near-term and long-term, enabling temperature targets to be met at lower cost. There are major concerns around the scale of CDR deployment in many low-carbon scenarios, and the risk that anticipated future CDR could dilute incentives to reduce emissions now, a phenomenon known as mitigation deterrence. Here we conduct an in-depth analysis into the relationship between emissions reduction and emissions removal in a global integrated assessment model. We explore the impact of CDR on low-carbon scenarios, illustrating how the pathway for the 2020s is highly sensitive to assumptions around CDR availability. Using stochastic optimisation, we demonstrate that accounting for uncertainty in future CDR deployment provides a strong rationale to increase rates of mitigation in the 2020s. A 20% chance of CDR deployment failure requires additional emissions reduction in 2030 of 3–17 GtCO2. Finally, we introduce new scenarios which demonstrate the risks of mitigation deterrence and the benefits of formally separating CDR and emissions reduction as climate strategies. Continual mitigation deterrence across the time-horizon leads to the temperature goals being breached by 0.2–0.3 °C. If CDR is treated as additional to emissions reduction, up to an additional 700–800 GtCO2 can be removed from the atmosphere by 2100, reducing end-of-century warming by up to 0.5 °C. This could put sub-1.5 °C targets within reach but requires that CDR is additional to, rather than replaces, emission reductions.

Journal article

Nikas A, Elia A, Boitier B, Koasidis K, Doukas H, Cassetti G, Anger-Kraavi A, Bui H, Campagnolo L, De Miglio R, Delpiazzo E, Fougeyrollas A, Gambhir A, Gargiulo M, Giarola S, Grant N, Hawkes A, Herbst A, Köberle AC, Kolpakov A, Le Mouël P, McWilliams B, Mittal S, Moreno J, Neuner F, Perdana S, Peters GP, Plötz P, Rogelj J, Sognnæs I, Van de Ven D-J, Vielle M, Zachmann G, Zagamé P, Chiodi Aet al., 2021, Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison., Science of the Total Environment, Vol: 793, Pages: 148549-148549, ISSN: 0048-9697

Recent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns. The output of this process is a scenario framework exploring where the region is headed rather than how to achieve its goals, extrapolating its current policy efforts into the future. We find that Europe is currently on track to overperforming its pre-2020 40% target yet far from its newest ambition of 55% emissions cuts by 2030, as well as looking at a 1.0-2.35 GtCO2 emissions range in 2050. Aside from the importance of transport electrification, deployment levels of carbon capture and storage are found intertwined with deeper emissions cuts and with hydrogen diffusion, with most hydrogen produced post-2040 being blue. Finally, the multi-model exercise has highlighted benefits from deeper decarbonisation in terms of energy security and jobs, and moderate to high renewables-dominated investment needs.

Journal article

Grant N, Hawkes A, Napp T, Gambhir Aet al., 2020, The appropriate use of reference scenarios in mitigation analysis, Nature Climate Change, Vol: 10, Pages: 605-610, ISSN: 1758-678X

Comparing emissions scenarios is an essential part of mitigation analysis, as climate targets can be met in various ways with different economic, energy system and co-benefit implications. Typically, a central ‘reference scenario’ acts as a point of comparison, and often this has been a no policy baseline with no explicit mitigative action taken. The use of such baselines is under increasing scrutiny, raising a wider question around the appropriate use of reference scenarios in mitigation analysis. In this Perspective, we assess three critical issues relevant to the use of reference scenarios, demonstrating how different policy contexts merit the use of different scenarios. We provide recommendations to the modelling community on best practice in the creation, use and communication of reference scenarios.

Journal article

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