Using expert elicitation to strengthen future regional climate information for climate services

<p>Climate change knowledge can inform regional and local adaptation decisions. However, estimates of future climate are uncertain and methods for assessing uncertainties typically rely on the results of climate model simulations, which are constrained by the quality of assumptions used in model experiments and the limitations of available models. To strengthen knowledge for adaptation decisions, we use structured expert elicitation to assess future climate change in the Lower Yangtze region in China. We elicit judgements on future changes in temperature and precipitation as well as uncertainty sources, comparing elicited judgements and model outputs from phase 5 of the Couple Model Intercomparison Project (CMIP5). We find high consensus amongst experts that the Lower Yangtze region will be warmer in the coming decades, albeit with differences in the magnitude of change. There is less consensus around the direction and magnitude of change for future precipitation change in the region. When compared with CMIP5 model outputs, experts provide similar or narrower uncertainty ranges for temperature change and diverse ranges for precipitation. Experts considered additional factors (e.g. model credibility, observations, theory and paleo-climatic evidence) and uncertainties not usually represented in conventional modelling approaches. We explore the value in bringing together multiple lines of evidence in the context of climate services, arguing that while decision makers should not rely solely on expert judgements, this information can complement model information to strengthen regional climate change knowledge. These multiple lines of evidence can help in building dialogue between climate experts and regional stakeholders, contributing to the development of climate services. </p>

Long-term intensification of the East Asian Summer Monsoon (EASM) lifecycle based on observation and CMIP6

<p>In 2018, Japan experienced successive extremes, flood and following heat wave. The East Asian summer monsoon (EASM) has lifecycle and depending on the cycle, the basic condition of rainfall and heat event is decided. Thus, to examine the variability to the basic condition which is capable to make extreme event favorable, the long-term change of the EASM lifecycle is analyzed based on observation datasets and historical simulations of the Couple Model Intercomparison Project Phase 6 (CMIP6).</p><p> According to the observation, the active phase of EASM has intensified and the break phase becomes longer, resulting in a shorter but stronger rainy season followed by a longer dry spell. This intensification in the precipitation evolution is accompanied by increased lower tropospheric southwesterly wind and convergence of water vapor flux, suggesting a dynamical cause. The widely reported westward extension of the Western North Pacific Subtropical High associated with the warming climate is a likely driver. Some of the CMIP6 models were able to capture the climatology of the EASM lifecycle and its intensification similar to those observed, but the majority of models still did not properly simulate the EASM lifecycle.</p>

Evaluating the Risk-Based Performance of Bioinfiltration Facilities under Climate Change Scenarios

Many communities throughout the world are utilizing green infrastructure practices to mitigate the projected impacts of climate change. While some areas of the world are anticipating droughts, other areas are preparing for an increased flood risk, due to changes in precipitation volume and intensity. Cities rely on practices such as bioinfiltration to sustainably capture stormwater runoff and provide resilience against climate change. As cities aim to increase resilience and decrease climate-change-associated risks, a greater understanding of these risks is needed. A risk-based approach was used to evaluate bioinfiltration design and performance. Climate projections from the Couple Model Intercomparison Project Phase 5 were used to create near-term (2020–2049) and long-term (2050–2079) climate datasets for Philadelphia, Pennsylvania, using two representative concentration pathways (RCPs 2.6 and 8.5). Both near-term and long-term climate models demonstrated increased precipitation and daily temperatures, similar to other areas in the U.S. Northeast, Midwest, Great Plains, and Alaska. Climate data were used to model bioinfiltration practices using continuous simulation hydrologic models. Overflow events and cumulative risk increased from bioinfiltration sites when compared to the baseline scenario (1970–1999). This study demonstrates how to apply a risk-based approach to bioinfiltration design using climate projections and provides recommendations to increase resilience in bioinfiltration design.