Benefits Cost Anaylsis: Options for Sea Level Rise Adaptation on West Cliff Drive

This report presents the results of a benefit cost analysis of various options for adapting West Cliff Drive (in the City of Santa Cruz, California) to sea level rise as identified through extensive technical analysis and community input. This report has built on previous work completed as part of the West Cliff Drive Adaptation and Management Plan project. The previous work products provided much of the information needed for this benefit cost analysis included an existing conditions inventory, future exposure and vulnerability assessment, and an adaptation alternatives analysis. Since most of the West Cliff Drive corridor is publicly owned by the City of Santa Cruz and California State Parks, results of the future exposure and vulnerability assessment showed that little private property and only small portions of public infrastructure is at risk in the future. Thus, the benefit cost analysis focuses primarily on changes to the recreational uses of the West Cliff Drive corridor. One challenge to adaptation planning is the uncertainty associated with the rate and elevation of sea level rise at future points of time, critical to the question of what to do and when. To deal with this uncertainty, the benefit cost analysis uses a technique called Monte Carlo analysis, a technique to test many different possible scenarios of sea level rise; in this analysis, 100,000 different scenarios were examined in every run of the analysis. The underlying sea level rise data is the same as used by the State of California in its various sea level rise planning guidance documents. This approach to the benefit cost analysis allows an estimate not only of net benefits but also the probability of positive net benefits of each adaptation strategy. The purpose of this benefit cost analysis is to compare the economic benefits and costs of the coastal adaptation options aimed at managing coastal erosion to a future in which no additional adaptation actions beyond those routinely taken by the City are taken. The benefit cost analysis is designed to support a choice between those different adaptation strategies which involve substantial new expenditures by the City the or “business as usual” strategy. The fundamental question is whether it is economically worthwhile for the City to invest substantial resources in adapting to sea level rise along West Cliff Drive compared with continuing as they have in the past? Economically worthwhile projects have benefits greater than costs, taking into account the differences in timing of spending and receipt of benefits. This concept is called the net present value. Four scenarios are examined: Business as Usual – No actions are taken beyond routine maintenance and irregular emergency repairs Managed Retreat – Existing armoring structures are removed, and natural erosion and shoreline processes restored. Recreation Focused Strategy – A combination of sand management, reduction in coastal armoring footprints and sand retention structures along with structural adaptation in high hazard areas such as sea caves. Protection Focused Strategy – Projects that stabilize the shoreline such as revetments, seawalls, filling of sea caves, and construction of artificial bedrock

Complexity and Creativity

An online seminar delivered on the relationship between complexity and creativity. Revell gave a short talk followed by a discussion with around 60 particpants. --- Through talks, discussion and other activities the seminars will explore how open and creative approaches to teaching and learning can help students navigate the complexity of higher education and the digital environment. The seminars are designed for anyone in a teaching, teaching related or staff development role in higher education. Each seminar runs for approximately 1 hour with some time at the end for additional discussion

A Strategic Approach to Developing the Role of Perennial Forages for Crop-Livestock Farmers

A substantial proportion of Australian animal production from grazing comes from regions and farms where cropping is the major enterprise. Developing new and improved grazing systems for mixed farms where crop production is the major driver of farm management decisions presents a unique research and development challenge. In this paper we describe a multi-disciplinary farming-systems research approach (‘EverCrop’) aimed at improving farm profitability, risk management and environmental impacts through the development and integration of new grazing options. It has been used to analyse and target new opportunities for farmers to benefit from perennial species across dry Mediterranean-type and temperate regions of southern Australia. It integrates field experimentation, on-farm trialling, farmer participatory research, soil-plant-climate biophysical modelling, whole-farm bioeconomic analysis and evaluations of adoptability. Multi-functional roles for summer-active grasses with winter cropping, integration of forage shrubs and establishment of new mixes of perennial grasses in crop rotations to improve farming-system performance are identified, along with an analysis of uptake by farmers

Long-term survival and center volume for functionally single-ventricle congenital heart disease in England and Wales

OBJECTIVES: Long-term survival is an important metric for health care evaluation, especially in functionally single-ventricle (f-SV) congenital heart disease (CHD). This study's aim was to evaluate the relationship between center volume and long-term survival in f-SV CHD within the centralized health care service of England and Wales. METHODS: This was a retrospective cohort study of children born with f-SV CHD between 2000 and 2018, using the national CHD procedure registry, with survival ascertained in 2020. RESULTS: Of 56,039 patients, 3293 (5.9%) had f-SV CHD. Median age at first intervention was 7 days (interquartile range [IQR], 4, 27), and median follow-up time was 7.6 years (IQR, 1.0, 13.3). The largest diagnostic subcategories were hypoplastic left heart syndrome, 1276 (38.8%); tricuspid atresia, 440 (13.4%); and double-inlet left ventricle, 322 (9.8%). The survival rate at 1 year and 5 years was 76.8% (95% confidence interval [CI], 75.3%-78.2%) and 72.1% (95% CI, 70.6%-73.7%), respectively. The unadjusted hazard ratio for each 5 additional patients with f-SV starting treatment per center per year was 1.04 (95% CI, 1.02-1.06), P < .001. However, after adjustment for significant risk factors (diagnostic subcategory; antenatal diagnosis; younger age, low weight, acquired comorbidity, increased severity of illness at first procedure), the hazard ratio for f-SV center volume was 1.01 (95% CI, 0.99-1.04) P = .28. There was strong evidence that patients with more complex f-SV (hypoplastic left heart syndrome, Norwood pathway) were treated at centers with greater f-SV case volume (P < .001). CONCLUSIONS: After adjustment for case mix, there was no evidence that f-SV center volume was linked to longer-term survival in the centralized health service provided by the 10 children's cardiac centers in England and Wales

Inter-model comparison of global hydroxyl radical (OH) distributions and their impact on atmospheric methane over the 2000–2016 period

The modeling study presented here aims to estimate how uncertainties in global hydroxyl radical (OH) distributions, variability, and trends may contribute to resolving discrepancies between simulated and observed methane (CH4) changes since 2000. A multi-model ensemble of 14 OH fields was analyzed and aggregated into 64 scenarios to force the offline atmospheric chemistry transport model LMDz (Laboratoire de Meteorologie Dynamique) with a standard CH4 emission scenario over the period 2000–2016. The multi-model simulated global volume-weighted tropospheric mean OH concentration ([OH]) averaged over 2000–2010 ranges between 8:7*10^5 and 12:8*10^5 molec cm-3. The inter-model differences in tropospheric OH burden and vertical distributions are mainly determined by the differences in the nitrogen oxide (NO) distributions, while the spatial discrepancies between OH fields are mostly due to differences in natural emissions and volatile organic compound (VOC) chemistry. From 2000 to 2010, most simulated OH fields show an increase of 0.1–0:3*10^5 molec cm-3 in the tropospheric mean [OH], with year-to-year variations much smaller than during the historical period 1960–2000. Once ingested into the LMDz model, these OH changes translated into a 5 to 15 ppbv reduction in the CH4 mixing ratio in 2010, which represents 7%–20% of the model-simulated CH4 increase due to surface emissions. Between 2010 and 2016, the ensemble of simulations showed that OH changes could lead to a CH4 mixing ratio uncertainty of > 30 ppbv. Over the full 2000–2016 time period, using a common stateof- the-art but nonoptimized emission scenario, the impact of [OH] changes tested here can explain up to 54% of the gap between model simulations and observations. This result emphasizes the importance of better representing OH abundance and variations in CH4 forward simulations and emission optimizations performed by atmospheric inversions

Changes to population-based emergence of climate change from CMIP5 to CMIP6

The Coupled Model Intercomparison Project Phase 6 (CMIP6) model ensemble projects climate change emerging soonest and most strongly at low latitudes, regardless of the emissions pathway taken. In terms of signal-to-noise (S/N) ratios of average annual temperatures, these models project earlier and stronger emergence under the Shared Socio-economic Pathways (SSPs) than the previous generation did under corresponding Representative Concentration Pathways (RCPs). Spatial patterns of emergence also change between generations of models; under a high emissions scenario, mid-century S/N is lower than previous studies indicated in Central Africa, South Asia, and parts of South America, West Africa, East Asia, and Western Europe, but higher in most other populated areas. We show that these global and regional changes are caused by a combination of higher effective climate sensitivity (ECS) in the CMIP6 ensemble, as well as changes to emissions pathways, component-wise effective radiative forcing (ERF), and region-scale climate responses between model generations. We also present the first population-weighted calculation of climate change emergence for the CMIP6 ensemble, quantifying the number of people exposed to increasing degrees of abnormal temperatures now and into the future. Our results confirm the expected inequity of climate change-related impacts in the decades between now and the 2050 target for net-zero emissions held by many countries. These findings underscore the importance of concurrent investments in both mitigation and adaptation

Evaluating the relationship between interannual variations in the Antarctic ozone hole and Southern Hemisphere surface climate in chemistry-climate models

Studies have recently reported statistically significant relationships between observed year-to-year spring Antarctic ozone variability and the Southern Hemisphere Annular Mode and surface temperatures in spring-summer. This study investigates whether current chemistry-climate models (CCMs) can capture these relationships, in particular, the connection between November total column ozone (TCO) and Australian summer surface temperatures, where years with anomalously high TCO over the Antarctic polar cap tend to be followed by warmer summers. The interannual ozone-temperature teleconnection is examined over the historical period in the observations and simulations from the Whole Atmosphere Community Climate Model (WACCM) and nine other models participating in the Chemistry-Climate Model Initiative (CCMI). There is a systematic difference between the WACCM experiments forced with prescribed observed sea surface temperatures (SSTs) and those with an interactive ocean. Strong correlations between TCO and Australian temperatures are only obtained for the uncoupled experiment, suggesting that the SSTs could be important for driving both variations in Australian temperatures and the ozone hole, with no causal link between the two. Other CCMI models also tend to capture this relationship with more fidelity when driven by observed SSTs, though additional research and targeted modelling experiments are required to determine causality and further explore the role of model biases and observational uncertainty. The results indicate that CCMs can reproduce the relationship between spring ozone and summer Australian climate reported in observational studies, suggesting that incorporating ozone variability could improve seasonal predictions, however more work is required to understand the difference between the coupled and uncoupled simulations

Evaluating the relationship between interannual variations in the Antarctic ozone hole and Southern Hemisphere surface climate in chemistry-climate models

Studies have recently reported statistically significant relationships between observed year-to-year spring Antarctic ozone variability and the Southern Hemisphere Annular Mode and surface temperatures in spring-summer. This study investigates whether current chemistry-climate models (CCMs) can capture these relationships, in particular, the connection between November total column ozone (TCO) and Australian summer surface temperatures, where years with anomalously high TCO over the Antarctic polar cap tend to be followed by warmer summers. The interannual ozone-temperature teleconnection is examined over the historical period in the observations and simulations from the Whole Atmosphere Community Climate Model (WACCM) and nine other models participating in the Chemistry-Climate Model Initiative (CCMI). There is a systematic difference between the WACCM experiments forced with prescribed observed sea surface temperatures (SSTs) and those with an interactive ocean. Strong correlations between TCO and Australian temperatures are only obtained for the uncoupled experiment, suggesting that the SSTs could be important for driving both variations in Australian temperatures and the ozone hole, with no causal link between the two. Other CCMI models also tend to capture this relationship with more fidelity when driven by observed SSTs, though additional research and targeted modelling experiments are required to determine causality and further explore the role of model biases and observational uncertainty. The results indicate that CCMs can reproduce the relationship between spring ozone and summer Australian climate reported in observational studies, suggesting that incorporating ozone variability could improve seasonal predictions, however more work is required to understand the difference between the coupled and uncoupled simulations

The influence of mixing on the stratospheric age of air changes in the 21st century

Climate models consistently predict an acceleration of the Brewer–Dobson circulation (BDC) due to climate change in the 21st century. However, the strength of this acceleration varies considerably among individual models, which constitutes a notable source of uncertainty for future climate projections. To shed more light upon the magnitude of this uncertainty and on its causes, we analyse the stratospheric mean age of air (AoA) of 10 climate projection simulations from the Chemistry-Climate Model Initiative phase 1 (CCMI-I), covering the period between 1960 and 2100. In agreement with previous multi-model studies, we find a large model spread in the magnitude of the AoA trend over the simulation period. Differences between future and past AoA are found to be predominantly due to differences in mixing (reduced aging by mixing and recirculation) rather than differences in residual mean transport. We furthermore analyse the mixing efficiency, a measure of the relative strength of mixing for given residual mean transport, which was previously hypothesised to be a model constant. Here, the mixing efficiency is found to vary not only across models, but also over time in all models. Changes in mixing efficiency are shown to be closely related to changes in AoA and quantified to roughly contribute 10 % to the long-term AoA decrease over the 21st century. Additionally, mixing efficiency variations are shown to considerably enhance model spread in AoA changes. To understand these mixing efficiency variations, we also present a consistent dynamical framework based on diffusive closure, which highlights the role of basic state potential vorticity gradients in controlling mixing efficiency and therefore aging by mixing.Helmholtz Association | Ref. VH-NG-1014Australian Research Council’s Centre of Excellence for Climate System Science | Ref. CE110001028Australian Government’s National Computational Merit Allocation Scheme | Ref. FUERZAS 4012Ministerio de Ciencia e Innovación | Ref. CGL2015-71575-PNew Zealand Royal Society Marsden Fund | Ref. 12-NIW-00