Volcanic Eruptions: A Source of Irreducible Uncertainty for Future Climates

Volcanic forcing, a major natural source of climate variability, represents a challenge for current climate modeling because of the unpredictability and specificity of individual eruptions, and because of the complexity of processes linking the eruption to the climate response. Volcanic forcing is largely underrepresented in available future climate projections, which is a critical problem. The study by Man Mei Chim and Colleagues (Chim et al., 2023, https://doi.org/10.1029/2023GL103743) tackles this known unknown and reveals how climatically relevant volcanic activity may be stronger than currently thought in a future warmer climate, enhancing uncertainty of climate projections. The study exemplifies the profound implications of inaccuracies within simplified climate scenarios and motivates new research on volcanically forced climate variability. It also arouses some thoughts on climate uncertainty communication

Communicating, tailoring and using climate projections in adaptation planning

Planning for adaptation to climate change is often considered to be more effective if grounded on a solid evidence base and recognisant of relevant climate projections. How these climate projections are communicated, perceived and used is thus a key part of the adaptation process. The process of creating communications and communication tools that are considered usable by the intended users and therefore considered to be effective decision support is impacted by a range of complex factors that need to be considered in conjunction with each other. The aim of this thesis is to examine the challenges for the communication, tailoring and use of climate projections for adaptation planning in Germany and the UK, both considered leaders on climate change adaptation, and suggest how cross-level insights from the individual, local and national scale can help to advance a more comprehensive understanding of the usability of communication tools for adaptation planning. This research adopts a multi-level perspective by exploring scientific uncertainty communication in national level adaptation strategies, usability of climate projections for local adaptation planning and comprehension and use of tailored information at the individual level. The thesis takes a mixed methods approach combining qualitative analysis from documentary and interview research with quantitative analysis using survey results. Climate projections are inherently uncertain and their communication is thus always linked to the challenge of communicating physical science uncertainty. Based on the development of a new uncertainty assessment framework for comparing approaches to the inclusion and communication of physical science uncertainty, marked differences between the National Adaptation Strategies (NAS) of ten European countries are found. Through the examination of the English and German NAS in particular, this thesis theorises that similar stages of development in adaptation policy planning can nevertheless result in differences in the handling and communication of physical science uncertainty. In addition, the results show that the wider socio-political context within which the NAS are framed affects the extent to which physical science uncertainties are communicated comprehensively. This socio-political and wider regulatory and legal context is also found to impact the demand for and use of climate projections for local adaptation planning in both England and Germany. Local planning in England has not only experienced a decline in use of climate projections, but the waning of the adaptation agenda more widely, amidst local government budget cuts and other adverse policy changes. In Germany, spatial planning makes substantial use of current climate information but the strictly regulated nature of planning prevents the use of climate projections, due to their inherent uncertainties. These findings highlight that the communication of climate projections is more effective at the local level when it is mindful of the wider context within which planning decisions are made, as this will impact the usability of provided tools and information. As the adaptation agenda within the local government planning context is often the predominant responsibility of only very few people within a given local authority, this thesis also empirically tests a number of different graph formats for the provision of climate projection information. The findings show that respondents appear to use the graph formats for their own planning decisions or for communicating with other staff within the council that they think they understand the best, rather than the ones they actually understand the best. There is no consistent association between users’ assessed comprehension and perceived comprehension, which highlights that effective information tailoring according to user needs, will require a more individualised approach and more systematic empirical testing. These findings highlight that audience specific targeted communication to support well-informed adaptation planning may be more challenging than previously thought. If the aim is to increase usability of climate projections through tailored communication, it is important to jointly consider the particular constraints or requirements of the wider socio-political and institutional context within which adaptation planning takes place as well as recognise the varying needs, demands and preferences of the individual adaptation practitioner. This research helps to provide key considerations for the provision and design of more usable tools for communicating climate change projections within their intended adaptation planning context

Uncertainties in the timing of unprecedented climates

The question of when the signal of climate change will emerge from the background noise of climate variability—the ‘time of emergence’—is potentially important for adaptation planning. Mora et al.1 presented precise projections of the time of emergence of unprecedented regional climates. However, their methodology produces artificially early dates at which specific regions will permanently experience unprecedented climates and artificially low uncertainty in those dates everywhere. This overconfidence could impair the effectiveness of climate risk management decisions 2. There is a Reply to this Brief Communication Arising by Mora, C. et al. Nature 511, http://dx.doi.org/10.1038/nature13524 (2014)

Assessing reservoir operations risk under climate change

Risk-based planning offers a robust way to identify strategies that permit adaptive water resources management under climate change. This paper presents a flexible methodology for conducting climate change risk assessments involving reservoir operations. Decision makers can apply this methodology to their systems by selecting future periods and risk metrics relevant to their planning questions and by collectively evaluating system impacts relative to an ensemble of climate projection scenarios (weighted or not). This paper shows multiple applications of this methodology in a case study involving California\u27s Central Valley Project and State Water Project systems. Multiple applications were conducted to show how choices made in conducting the risk assessment, choices known as analytical design decisions, can affect assessed risk. Specifically, risk was reanalyzed for every choice combination of two design decisions: (1) whether to assume climate change will influence flood-control constraints on water supply operations (and how), and (2) whether to weight climate change scenarios (and how). Results show that assessed risk would motivate different planning pathways depending on decision-maker attitudes toward risk (e.g., risk neutral versus risk averse). Results also show that assessed risk at a given risk attitude is sensitive to the analytical design choices listed above, with the choice of whether to adjust flood-control rules under climate change having considerably more influence than the choice on whether to weight climate scenarios

Why Simpler Computer Simulation Models Can Be Epistemically Better for Informing Decisions

For computer simulation models to usefully inform climate risk management, uncertainties in model projections must be explored and characterized. Because doing so requires running the model many ti..

Climate Change and Sea Level Rise Projections for Boston

While the broad outlines of how climate change would impact Boston have been known for some time, it is only recently that we have developed a more definitive understanding of what lies ahead. That understanding was advanced considerably with the publication of Climate Change and Sea Level Rise Projections for Boston by the Boston Research Advisory Group (BRAG).The BRAG report is the first major product of "Climate Ready Boston," a project led by the City of Boston in partnership with the Green Ribbon Commission and funded in part by the Barr Foundation. The BRAG team includes 20 leading experts from the region's major universities on subjects ranging from sea level rise to temperature extremes. University of Massachusetts Boston professors Ellen Douglas and Paul Kirshen headed the research.The BRAG report validates earlier studies, concluding Boston will get hotter, wetter, and saltier in the decades ahead (see figures below). But the group has produced a much more definitive set of projections than existed previously, especially for the problem of sea level rise. BRAG also concluded that some of the effects of climate change will come sooner than expected, accelerating the urgency of planning and action

A framework for modeling uncertainty in regional climate change

In this study, we present a new modeling framework and a large ensemble of climate projections to investigate the uncertainty in regional climate change over the United States (US) associated with four dimensions of uncertainty. The sources of uncertainty considered in this framework are the emissions projections, global climate system parameters, natural variability and model structural uncertainty. The modeling framework revolves around the Massachusetts Institute of Technology (MIT) Integrated Global System Model (IGSM), an integrated assessment model with an Earth System Model of Intermediate Complexity (EMIC) (with a two-dimensional zonal-mean atmosphere). Regional climate change over the US is obtained through a two-pronged approach. First, we use the IGSM-CAM framework, which links the IGSM to the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). Second, we use a pattern-scaling method that extends the IGSM zonal mean based on climate change patterns from various climate models. Results show that the range of annual mean temperature changes are mainly driven by policy choices and the range of climate sensitivity considered. Meanwhile, the four sources of uncertainty contribute more equally to end-of-century precipitation changes, with natural variability dominating until 2050. For the set of scenarios used in this study, the choice of policy is the largest driver of uncertainty, defined as the range of warming and changes in precipitation, in future projections of climate change over the US