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31 results on '"Lempert, R."'

1. Robust Decision Making (RDM)

Author

Lempert, R. J., Marchau, Vincent A. W. J., editor, Walker, Warren E., editor, Bloemen, Pieter J. T. M., editor, and Popper, Steven W., editor

Published
2019
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2. Cross-Chapter Box PROGRESS : Approaches and Challenges to Assess Adaptation Progress at the Global Level

Author

Garschagen, M., Leiter, T., Biesbroek, G.R., Magnan, A.K., Reckien, Diana, New, M., Berrang-Ford, L., Cheong, S.M., Schipper, L., Lempert, R., Garschagen, M., Leiter, T., Biesbroek, G.R., Magnan, A.K., Reckien, Diana, New, M., Berrang-Ford, L., Cheong, S.M., Schipper, L., and Lempert, R.

Abstract

Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

Published
2023

3. Resilience Of The Eastern African Electricity Sector To Climate Driven Changes In Hydropower Generation

Author

Perera, A., Rieu-Clark, A., Hunt, J., Neupane, B., Chuphal, D.S., Sridharan, V., Broad, O., Shivakumar, A., Howells, M., Boehlert, B., Groves, D.G., Rogner, H., Taliotis, C., Neumann, J., Strzepek, K., Lempert, R., Joyce, B., Huber-Lee, A., Cervigni, R., Perera, A., Rieu-Clark, A., Hunt, J., Neupane, B., Chuphal, D.S., Sridharan, V., Broad, O., Shivakumar, A., Howells, M., Boehlert, B., Groves, D.G., Rogner, H., Taliotis, C., Neumann, J., Strzepek, K., Lempert, R., Joyce, B., Huber-Lee, A., and Cervigni, R.

Published
2023

5. Terrestrial and Freshwater Ecosystems and Their Services

Author

Singh, Bettina, Parmesan, C, Morecroft, MD, Trisurat, Y, Adrian, R, Anshari, GZ, Arneth, A, Gao, Q, Gonzalez, P, Harris, R, Price, J, Stevens, N, Talukdar, GH, Strutz, SE, Ackerly, DD, Anderson, E, Boyd, P, Birkmann, J, Bremerich, V, Brotons, L, Buotte, P, Campbell, D, Castellanos, E, Chen, Y-Y, Cissé, G, Cooley, S, Cowie, A, Dhimal, M, Domisch, S, Donner, S, Douwes, Errol, Escobar, LE, Rivera Ferre, M, Flecker, A, Foden, W, Gallagher, RV, Gaxiola, A, Gemeda, A, Goulding, M, Grey, K-A, López Gunn, E, Harrison, S, Hicke, J, Hilmi, NJM, Barragan-Jason, G, Keith, DA, Bezner Kerr, R, Kraemer, BM, Langhans, S, Lasco, R, Latimer, A, Lempert, R, Lluch-Cota, SE, Loisel, J, Mackey, J, Martinetto, P, Matthews, R, McPhearson, T, Mauritzen, M, Midgley, G, Mordecai, E, Moreira, F, Mukherji, A, Myers-Smith, I, Nabuurs, G-J, Neufeldt, H, Pearce-Higgins, J, Pecl, G, Pedace, R, Townsend Peterson, A, Piepenburg, D, Postigo, JC, Pulhin, J, Racault, M-F, Rocklöv, J, Rogelj, J, Rost, B, Romanello, M, Gallego-Sala, A, Schmidt, D, Schoeman, D, Seddon, N, Semenza, JC, Singer, MC, Singh, PK, Slingsby, J, Smith, P, Sukumar, R, Tirado, MC, Trisos, C, Turetsky, M, Turner, B, van Aalst, M, Young, K, Singh, Bettina, Parmesan, C, Morecroft, MD, Trisurat, Y, Adrian, R, Anshari, GZ, Arneth, A, Gao, Q, Gonzalez, P, Harris, R, Price, J, Stevens, N, Talukdar, GH, Strutz, SE, Ackerly, DD, Anderson, E, Boyd, P, Birkmann, J, Bremerich, V, Brotons, L, Buotte, P, Campbell, D, Castellanos, E, Chen, Y-Y, Cissé, G, Cooley, S, Cowie, A, Dhimal, M, Domisch, S, Donner, S, Douwes, Errol, Escobar, LE, Rivera Ferre, M, Flecker, A, Foden, W, Gallagher, RV, Gaxiola, A, Gemeda, A, Goulding, M, Grey, K-A, López Gunn, E, Harrison, S, Hicke, J, Hilmi, NJM, Barragan-Jason, G, Keith, DA, Bezner Kerr, R, Kraemer, BM, Langhans, S, Lasco, R, Latimer, A, Lempert, R, Lluch-Cota, SE, Loisel, J, Mackey, J, Martinetto, P, Matthews, R, McPhearson, T, Mauritzen, M, Midgley, G, Mordecai, E, Moreira, F, Mukherji, A, Myers-Smith, I, Nabuurs, G-J, Neufeldt, H, Pearce-Higgins, J, Pecl, G, Pedace, R, Townsend Peterson, A, Piepenburg, D, Postigo, JC, Pulhin, J, Racault, M-F, Rocklöv, J, Rogelj, J, Rost, B, Romanello, M, Gallego-Sala, A, Schmidt, D, Schoeman, D, Seddon, N, Semenza, JC, Singer, MC, Singh, PK, Slingsby, J, Smith, P, Sukumar, R, Tirado, MC, Trisos, C, Turetsky, M, Turner, B, van Aalst, M, and Young, K

Published
2022

6. Technical Summary

Author

Pörtner, Hans-Otto, Roberts, D.C., Adams, H., Adelekan, I., Adler, C., Adrian, R., Aldunce, Paulina, Ali, Elham, Ara Begum, R., Bednar-Friedl, B., Kerr, Rachel Bezner, Biesbroek, G.R., Birkmann, J., Bowen, K., Caretta, M.A., Carnicer, Jofre, Castellanos, Edwin, Cheong, T.S., Chow, W., Cissé, Guéladio, Clayton, S., Constable, A., Cooley, S.R., Costello, M.J., Craig, M., Cramer, W., Dawson, R., Dodman, D., Efitre, J., Garschagen, M., Gilmore, E.A., Glavovic, B.C., Gutzler, D., Haasnoot, M., Harper, S., Hasegawa, T., Hayward, B., Hicke, J.A., Hirabayashi, Y., Huang, C., Kalaba, K., Kiessling, W., Kitoh, A., Lasco, R., Lawrence, J., Lemos, M.F., Lempert, R., Lennard, C., Ley, D., Lissner, T., Liu, Q., Liwenga, E., Lluch-Cota, Salvador, Löschke, S., Lucatello, S., Luo, Y., Mackey, B., Mintenbeck, Katja, Mirzabaev, A., Möller, V., Moncassim Vale, Mariana, Morecroft, M.D., Mortsch, L., Mukherji, A., Mustonen, Tero, Mycoo, Michelle, Nalau, J., New, M., Okem, A., Ometto, J.P., O'Neill, B., Pandey, R., Parmesan, Camille, Pelling, Mark, Pinho, P.F., Pinnegar, J., Poloczanska, E.S., Prakash, A., Preston, B., Racault, Marie-Fanny, Reckien, Diana, Revi, A., Rose, S.K., Schipper, E.L.F., Schmidt, D.N., Schoeman, D., Shaw, R., Simpson, N.P., Singh, C., Solecki, W., Stringer, L., Totin, E., Trisos, C.H., Trisurat, Y., van Aalst, M., Viner, D., Wairiu, Morgan, Warren, R., Wester, P., Wrathall, David, Zaiton Ibrahim, Zelina, Pörtner, Hans-Otto, Roberts, D.C., Adams, H., Adelekan, I., Adler, C., Adrian, R., Aldunce, Paulina, Ali, Elham, Ara Begum, R., Bednar-Friedl, B., Kerr, Rachel Bezner, Biesbroek, G.R., Birkmann, J., Bowen, K., Caretta, M.A., Carnicer, Jofre, Castellanos, Edwin, Cheong, T.S., Chow, W., Cissé, Guéladio, Clayton, S., Constable, A., Cooley, S.R., Costello, M.J., Craig, M., Cramer, W., Dawson, R., Dodman, D., Efitre, J., Garschagen, M., Gilmore, E.A., Glavovic, B.C., Gutzler, D., Haasnoot, M., Harper, S., Hasegawa, T., Hayward, B., Hicke, J.A., Hirabayashi, Y., Huang, C., Kalaba, K., Kiessling, W., Kitoh, A., Lasco, R., Lawrence, J., Lemos, M.F., Lempert, R., Lennard, C., Ley, D., Lissner, T., Liu, Q., Liwenga, E., Lluch-Cota, Salvador, Löschke, S., Lucatello, S., Luo, Y., Mackey, B., Mintenbeck, Katja, Mirzabaev, A., Möller, V., Moncassim Vale, Mariana, Morecroft, M.D., Mortsch, L., Mukherji, A., Mustonen, Tero, Mycoo, Michelle, Nalau, J., New, M., Okem, A., Ometto, J.P., O'Neill, B., Pandey, R., Parmesan, Camille, Pelling, Mark, Pinho, P.F., Pinnegar, J., Poloczanska, E.S., Prakash, A., Preston, B., Racault, Marie-Fanny, Reckien, Diana, Revi, A., Rose, S.K., Schipper, E.L.F., Schmidt, D.N., Schoeman, D., Shaw, R., Simpson, N.P., Singh, C., Solecki, W., Stringer, L., Totin, E., Trisos, C.H., Trisurat, Y., van Aalst, M., Viner, D., Wairiu, Morgan, Warren, R., Wester, P., Wrathall, David, and Zaiton Ibrahim, Zelina

Published
2022

9. Resilience of the Eastern African electricity sector to climate driven changes in hydropower generation

Author

Sridharan, Vignesh, Broad, Oliver, Shivakumar, Abhishek, Howells, Mark I., Boehlert, B., Groves, D. G., Rogner, Hans-Holger, Taliotis, C., Neumann, J. E., Strzepek, K. M., Lempert, R., Joyce, B., Huber-Lee, A., Cervigni, R., Sridharan, Vignesh, Broad, Oliver, Shivakumar, Abhishek, Howells, Mark I., Boehlert, B., Groves, D. G., Rogner, Hans-Holger, Taliotis, C., Neumann, J. E., Strzepek, K. M., Lempert, R., Joyce, B., Huber-Lee, A., and Cervigni, R.

Abstract

Notwithstanding current heavy dependence on gas-fired electricity generation in the Eastern African Power Pool (EAPP), hydropower is expected to play an essential role in improving electricity access in the region. Expansion planning of electricity infrastructure is critical to support investment and maintaining balanced consumer electricity prices. Variations in water availability due to a changing climate could leave hydro infrastructure stranded or result in underutilization of available resources. In this study, we develop a framework consisting of long-term models for electricity supply and water systems management, to assess the vulnerability of potential expansion plans to the effects of climate change. We find that the most resilient EAPP rollout strategy corresponds to a plan optimised for a slightly wetter climate compared to historical trends. This study demonstrates that failing to climate-proof infrastructure investments can result in significant electricity price fluctuations in selected countries (Uganda & Tanzania) while others, such as Egypt, are less vulnerable., QC 20190328

Published
2019
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10. Resilience of the Eastern African electricity sector to climate driven changes in hydropower generation

Author

Sridharan, V., Broad, O., Shivakumar, A., Howells, M., Boehlert, B., Groves, D.G., Rogner, H., Taliotis, C., Neumann, J.E., Strzepek, K.M., Lempert, R., Joyce, B., Huber-Lee, A., Cervigni, R., Sridharan, V., Broad, O., Shivakumar, A., Howells, M., Boehlert, B., Groves, D.G., Rogner, H., Taliotis, C., Neumann, J.E., Strzepek, K.M., Lempert, R., Joyce, B., Huber-Lee, A., and Cervigni, R.

Abstract

Notwithstanding current heavy dependence on gas-fired electricity generation in the Eastern African Power Pool (EAPP), hydropower is expected to play an essential role in improving electricity access in the region. Expansion planning of electricity infrastructure is critical to support investment and maintaining balanced consumer electricity prices. Variations in water availability due to a changing climate could leave hydro infrastructure stranded or result in underutilization of available resources. In this study, we develop a framework consisting of long-term models for electricity supply and water systems management, to assess the vulnerability of potential expansion plans to the effects of climate change. We find that the most resilient EAPP rollout strategy corresponds to a plan optimised for a slightly wetter climate compared to historical trends. This study demonstrates that failing to climate-proof infrastructure investments can result in significant electricity price fluctuations in selected countries (Uganda & Tanzania) while others, such as Egypt, are less vulnerable.

Published
2019

11. Choosing small sets of policy-relevant scenarios by combining vulnerability and diversity approaches

Author

Carlsen, H., Lempert, R., Wikman-Svahn, Per, Schweizer, V., Carlsen, H., Lempert, R., Wikman-Svahn, Per, and Schweizer, V.

Abstract

Computer simulation models can generate large numbers of scenarios, far more than can be effectively utilized in most decision support applications. How can one best select a small number of scenarios to consider? One approach calls for choosing scenarios that illuminate vulnerabilities of proposed policies. Another calls for choosing scenarios that span a diverse range of futures. This paper joins these two approaches for the first time, proposing an optimization-based method for choosing a small number of relevant scenarios that combine both vulnerability and diversity. The paper applies the method to a real case involving climate resilient infrastructure for three African river basins (Volta, Orange and Zambezi). Introducing selection criteria in a stepwise manner helps examine how different criteria influence the choice of scenarios. The results suggest that combining vulnerability- and diversity-based criteria can provide a systematic and transparent method for scenario selection., QC 20161111

Published
2016
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16. A frame-work for complex climate change risk assessment

Author

Nicholas Simpson, Mach, Constable A, Hess J, Hogarth R, Howden M, Lawrence J, Lempert R, Muccione V, Mackey B, Mg, New, O'Neill B, Otto F, H-O, Pörtner, Reisinger A, Roberts D, Schmidt D, Seneviratne S, Strongin S, van Aalst M, Totin E, and Trisos C

20. U.S. pharmaceutical policy in a global marketplace.

Author

Lakdawalla DN, Goldman DP, Michaud P, Sood N, Lempert R, Cong Z, Vries H, and Gutierrez I

Abstract

U.S. consumers generate more pharmaceutical revenue per person than Europeans do. This has led some U.S. policymakers to call for limits on U.S. pharmaceutical spending and prices. Using a microsimulation approach, we analyze the welfare impacts of lowering U.S. prices toward European levels, and how these impacts vary with key modeling assumptions. Under the assumptions most favorable to them, price controls generate modest benefits (a few thousand dollars per person). However, for the remainder of plausible assumptions, price controls generate costs that are an order of magnitude higher. In contrast, publicly financing reductions in consumer prices, without affecting manufacturer prices, delivers benefits in virtually all plausible cases. [ABSTRACT FROM AUTHOR]

Published
2009
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22. Reopening California: Seeking robust, non-dominated COVID-19 exit strategies.

Author

Nascimento de Lima P, Lempert R, Vardavas R, Baker L, Ringel J, Rutter CM, Ozik J, and Collier N

Subjects
Humans, California epidemiology, Uncertainty, Pandemics prevention & control, Decision Making, Public Health, Health Policy, COVID-19 epidemiology, COVID-19 prevention & control, SARS-CoV-2 isolation & purification
Abstract

The COVID-19 pandemic required significant public health interventions from local governments. Although nonpharmaceutical interventions often were implemented as decision rules, few studies evaluated the robustness of those reopening plans under a wide range of uncertainties. This paper uses the Robust Decision Making approach to stress-test 78 alternative reopening strategies, using California as an example. This study uniquely considers a wide range of uncertainties and demonstrates that seemingly sensible reopening plans can lead to both unnecessary COVID-19 deaths and days of interventions. We find that plans using fixed COVID-19 case thresholds might be less effective than strategies with time-varying reopening thresholds. While we use California as an example, our results are particularly relevant for jurisdictions where vaccination roll-out has been slower. The approach used in this paper could also prove useful for other public health policy problems in which policymakers need to make robust decisions in the face of deep uncertainty., Competing Interests: P. Nascimento de Lima, R. Lempert, L. Baker, J.S. Ringel, R. Vardavas and C. Rutter are affiliated with the RAND Corporation, a non-profit research organization. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Published
2021
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24. Reopening California : Seeking Robust, Non-Dominated COVID-19 Exit Strategies.

Author

de Lima PN, Lempert R, Vardavas R, Baker L, Ringel J, Rutter CM, Ozik J, and Collier N

Abstract

Amid global scarcity of COVID-19 vaccines and the threat of new variant strains, California and other jurisdictions face the question of when and how to implement and relax COVID-19 Nonpharmaceutical Interventions (NPIs). While policymakers have attempted to balance the health and economic impacts of the pandemic, decentralized decision-making, deep uncertainty, and the lack of widespread use of comprehensive decision support methods can lead to the choice of fragile or inefficient strategies. This paper uses simulation models and the Robust Decision Making (RDM) approach to stress-test California's reopening strategy and other alternatives over a wide range of futures. We find that plans which respond aggressively to initial outbreaks are required to robustly control the pandemic. Further, the best plans adapt to changing circumstances, lowering their stringent requirements to reopen over time or as more constituents are vaccinated. While we use California as an example, our results are particularly relevant for jurisdictions where vaccination roll-out has been slower.

Published
2021
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26. Resilience of the Eastern African electricity sector to climate driven changes in hydropower generation.

Author

Sridharan V, Broad O, Shivakumar A, Howells M, Boehlert B, Groves DG, Rogner HH, Taliotis C, Neumann JE, Strzepek KM, Lempert R, Joyce B, Huber-Lee A, and Cervigni R

Abstract

Notwithstanding current heavy dependence on gas-fired electricity generation in the Eastern African Power Pool (EAPP), hydropower is expected to play an essential role in improving electricity access in the region. Expansion planning of electricity infrastructure is critical to support investment and maintaining balanced consumer electricity prices. Variations in water availability due to a changing climate could leave hydro infrastructure stranded or result in underutilization of available resources. In this study, we develop a framework consisting of long-term models for electricity supply and water systems management, to assess the vulnerability of potential expansion plans to the effects of climate change. We find that the most resilient EAPP rollout strategy corresponds to a plan optimised for a slightly wetter climate compared to historical trends. This study demonstrates that failing to climate-proof infrastructure investments can result in significant electricity price fluctuations in selected countries (Uganda & Tanzania) while others, such as Egypt, are less vulnerable.

Published
2019
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27. Policy forum: studying eyewitness investigations in the field.

Author

Schacter DL, Dawes R, Jacoby LL, Kahneman D, Lempert R, Roediger HL, and Rosenthal R

Subjects
Diffusion of Innovation, Double-Blind Method, Humans, United States, Crime Victims, Police, Recognition, Psychology
Abstract

This article considers methodological issues arising from recent efforts to provide field tests of eyewitness identification procedures. We focus in particular on a field study (Mecklenburg 2006) that examined the "double blind, sequential" technique, and consider the implications of an acknowledged methodological confound in the study. We explain why the confound has severe consequences for assessing the real-world implications of this study.

Published
2008
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28. Robust reasoning with agent-based modeling.

Author

Bankes S and Lempert R

Abstract

Agent-based modeling (ABM) is a powerful representational formalism that has wide utility for modeling nonlinear systems. For ABM to achieve its potential as a scientific tool, our ability to build models that embody our knowledge must be complemented by rigorous means for making inferences using such models. Due to nonlinearity, this rigor cannot in general be based solely on demonstrating that a model reliably predicts the outcomes of available physical measurements. In this paper we describe an alternative approach to robust reasoning based on the concept of ensembles of alternative models. Ensembles of models can be defined that plausibly span classes of systems including the system of interest. Research methodologies for searching and sampling from such ensembles can be used to support plausible conclusions about invariant properties of ensembles of ABMs and hence of the classes of systems they represent. Notable among these are approaches that implement a competition between ensembles of problem formulations or challenges and conclusions robust to these challenges. This approach is demonstrated using examples drawn from our research.

Published
2004

29. Agent-based modeling as organizational and public policy simulators.

Author

Lempert R

Abstract

Agent-based models are an increasingly powerful tool for simulating social systems because they can represent important phenomenon difficult to capture in other mathematical formalisms. But, agent-based models have provided only limited support for policy-making because their distinctive abilities are often most useful in situations where the future is unpredictable. In such situations, the traditional analytic methods for applying simulation models to support decision-making are least effective. Fortunately, new analytic approaches for decision-making under conditions of deep uncertainty--emphasizing large ensembles of model-created scenarios and adaptive policies evaluated with the criteria of robustness, rather than with optimality or efficiency--can unleash the full potential of agent-based policy simulators.

Published
2002
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