More Like this

1. Integrating new sea‐level scenarios into coastal risk and adaptation assessments: An ongoing process

   https://doi.org/10.1002/wcc.706  

   Nicholls, Robert J.; Hanson, Susan E.; Lowe, Jason A.; Slangen, Aimée B. A.; Wahl, Thomas; Hinkel, Jochen; Long, Antony J. (March 2021, WIREs Climate Change)

   Abstract The release of new and updated sea‐level rise (SLR) information, such as from the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports, needs to be better anticipated in coastal risk and adaptation assessments. This requires risk and adaptation assessments to be regularly reviewed and updated as needed, reflecting the new information but retaining useful information from earlier assessments. In this paper, updated guidance on the types of SLR information available is presented, including for sea‐level extremes. An intercomparison of the evolution of the headline projected ranges across all the IPCC reports show an increase from the fourth and fifth assessments to the most recent “Special Report on the Ocean and Cryosphere in a Changing Climate” assessment. IPCC reports have begun to highlight the importance of potential high‐end sea‐level response, mainly reflecting uncertainties in the Greenland/Antarctic ice sheet components, and how this might be considered in scenarios. The methods that are developed here are practical and consider coastal risk assessment, adaptation planning, and long‐term decision‐making to be an ongoing process and ensure that despite the large uncertainties, pragmatic adaptation decisions can be made. It is concluded that new sea‐level information should not be seen as an automatic reason for abandoning existing assessments, but as an opportunity to review (i) the assessment's robustness in the light of new science and (ii) the utility of proactive adaptation and planning strategies, especially over the more uncertain longer term. This article is categorized under:Assessing Impacts of Climate Change > Scenario Development and Application 

   more » « less
2. The use of decision making under deep uncertainty in the IPCC

   https://doi.org/10.3389/fclim.2024.1380054  

   Lempert, Robert J; Lawrence, Judy; Kopp, Robert E; Haasnoot, Marjolijn; Reisinger, Andy; Grubb, Michael; Pasqualino, Roberto (June 2024, Frontiers in Climate)

   The Intergovernmental Panel on Climate Change (IPCC) exists to provide policy-relevant assessments of the science related to climate change. As such, the IPCC has long grappled with characterizing and communicating uncertainty in its assessments. Decision Making under Deep Uncertainty (DMDU) is a set of concepts, methods, and tools to inform decisions when there exist substantial and significant limitations on what is and can be known about policy-relevant questions. Over the last twenty-five years, the IPCC has drawn increasingly on DMDU concepts to more effectively include policy-relevant, but lower-confidence scientific information in its assessments. This paper traces the history of the IPCC’s use of DMDU and explains the intersection with key IPCC concepts such as risk, scenarios, treatment of uncertainty, storylines and high-impact, low-likelihood outcomes, and both adaptation and climate resilient development pathways. The paper suggests how the IPCC might benefit from enhanced use of DMDU in its current (7th) assessment cycle. 

   more » « less
3. Navigating confidence–precision trade-offs in assessment

   https://doi.org/10.1007/s10584-025-03935-2  

   Bradley, Richard; Helgeson, Casey; Hill, Brian (May 2025, Climatic Change)

   In this reply, we address a comment on our paper “Combining probability with qualitative degree-of-certainty metrics in assessment” (Helgeson et al. Clim Change 149(3):517–525, 2018). Our original paper proposes an incremental systematization of confidence and likelihood language used by the Intergovernmental Panel on Climate Change (IPCC). Our goals were to improve consistency across findings and support use of confidence judgments in decision making. The comment critiques our proposal and recommends against its adoption. We argue that this recommendation is based on two misunderstandings. The first concerns trading off confidence against the precision of a finding (our proposal endorses and systematizes the practice). We defend this practice and attribute opposition to an overzealous Bayesianism inapt for the IPCC context. The second misunderstanding concerns our purported commitment to a specific procedure for producing confidence judgements. We clarify that our proposal makes no such commitment. We also note, contrary to the comment’s claim, that a version of the procedure in question has been used in the IPCC’s Sixth Assessment Report. 

   more » « less
4. Mapping geographic and demographic shifts in container breeding mosquito-borne disease transmission suitability in Central and South America in a warming world

   https://doi.org/10.1101/2023.10.03.23296495  

   Ryan, Sadie J; Lippi, Catherine A; Stewart-Ibarra, Anna M (October 2023, medRxiv)

   Abstract The recent Intergovernmental Panel on Climate Change Sixth Assessment Report (IPCC-AR6) report brought into sharp relief the potential health impacts of a changing climate across large geographic regions. It also highlighted the gaps in available evidence to support detailed quantitative assessments of health impacts for many regions. In an increasingly urbanizing world, there is a need for additional information about the risk of mosquito-borne diseases from vectors adapted to human water storage behavior. Specifically, a better understanding of the geographic distribution of disease risk under different scenarios of climate warming and human populations shifts. For the Central and South America chapter of the IPCC Working Group II report, regional extractions of published projections of dengue and Zika risk in a changing climate were generated by one of the authors of this study. In that process, the lack of a compendium of available published risk estimates became apparent. This paper responds to that need and extends the scope of the IPCC report results for Central and South America. We present novel geospatial descriptions of risk for transmission for five mosquito-borne disease systems under future projected climate and demographic scenarios, including the potential risk for malaria in the event of the introduction and establishment of a vector of high global concern,Anopheles stephensi. We then present country-level and IPCC geospatial sub-region risk descriptions under baseline and future projected scenarios. By including demographic projections using the shared socioeconomic pathway (SSP) scenarios, we capture potential future risk in a way that is transparent and straightforward to compare and replicate. The goal of this paper is to report on these model output data and their availability. From a sub-regional perspective, the largest proportional gains in risk will be seen in the Southwestern South America (SWS) sub-region, comprising much of the southwestern coastline, for which suitability forAedes aegyptitransmitted dengue and Zika risk will see massive increases with warming, putting a large number of people at risk under future scenarios. In contrast, at the country level, the largest projected population risk impacts will be seen in Brazil for both arboviral and potential introduced malaria risk, despite some risks projected to decrease as parts of the country are too hot to sustain transmission risk. This paper provides modeled outputs for future use, in addition to broad summary descriptions at regional and country levels. 

   more » « less
5. A High‐End Estimate of Sea Level Rise for Practitioners

   https://doi.org/10.1029/2022EF002751  

   van de Wal, R. S. W.; Nicholls, R. J.; Behar, D.; McInnes, K.; Stammer, D.; Lowe, J. A.; Church, J. A.; DeConto, R.; Fettweis, X.; Goelzer, H.; et al (November 2022, Earth's Future)

   Abstract Sea level rise (SLR) is a long‐lasting consequence of climate change because global anthropogenic warming takes centuries to millennia to equilibrate for the deep ocean and ice sheets. SLR projections based on climate models support policy analysis, risk assessment and adaptation planning today, despite their large uncertainties. The central range of the SLR distribution is estimated by process‐based models. However, risk‐averse practitioners often require information about plausible future conditions that lie in the tails of the SLR distribution, which are poorly defined by existing models. Here, a community effort combining scientists and practitioners builds on a framework of discussing physical evidence to quantify high‐end global SLR for practitioners. The approach is complementary to the IPCC AR6 report and provides further physically plausible high‐end scenarios. High‐end estimates for the different SLR components are developed for two climate scenarios at two timescales. For global warming of +2°C in 2100 (RCP2.6/SSP1‐2.6) relative to pre‐industrial values our high‐end global SLR estimates are up to 0.9 m in 2100 and 2.5 m in 2300. Similarly, for a (RCP8.5/SSP5‐8.5), we estimate up to 1.6 m in 2100 and up to 10.4 m in 2300. The large and growing differences between the scenarios beyond 2100 emphasize the long‐term benefits of mitigation. However, even a modest 2°C warming may cause multi‐meter SLR on centennial time scales with profound consequences for coastal areas. Earlier high‐end assessments focused on instability mechanisms in Antarctica, while here we emphasize the importance of the timing of ice shelf collapse around Antarctica. This is highly uncertain due to low understanding of the driving processes. Hence both process understanding and emission scenario control high‐end SLR. 

   more » « less