Bridging Science and Policy Implication for Managing Climate Extremes

The following sections are included:

• Preface
• Contents

Recent drought events like in the 2011 Horn of Africa and the ongoing drought in California have an enormous impact on nature and society. Reliable seasonal weather outlooks are critical for drought management and other applications like, crop modelling, flood forecasting and planning of reservoir operation, and would help reduce the potential economic damage from extremes as well as help optimize crop yields during more normal weather years from improved agricultural management. However, most seasonal forecasts are limited by low spatial and temporal model resolutions. The newly released North American Multi-Model Ensemble phase 2 (NMME-2), provides subseasonal forecast that increase the temporal resolution from monthly to daily, enabling subseasonal forecasting for end-user applications that rely on a daily temporal resolution. In this study we give an overview of the current status of the NMME subseasonal forecasts ensembles, their skill over the African continent and the forecast skill of the ensembles for applications related to agriculture and hydrology. We show that the NMME-2 subseasonal forecasts are significantly skilful for both precipitation and 2 m air temperature for large parts of Africa. The precipitation forecasts are skilful up to a lead time of two months, while temperature anomaly forecasts have a significant skill beyond the three months lead for most of Africa. Potential applications that would benefit from the new NMME-2 ensemble were studied in more detail for West Africa. We show that the models have a significant skill in forecasting the onset of the annual rain season in West Africa, and thereby the start of the growing season. Additionally, the models have a significant forecast skill to predict the onset and peak of the high flow season for most parts of West Africa. The low uncertainty in the forecasts compared to the observed anomalies indicates that local stakeholders will benefit from the high temporal resolution that the NMME-2 provides. Results encourage future research into the potential of the new subseasonal NMME-2 forecast ensemble to forecast more specific end-user applications and climate services, which require skilful high temporal resolution forecasts.

The climate variability in tropical oceans plays an important role not only in the regional weather and climate but also in the extreme events leading to socio-economic loses. Here, the roles of some of those modes of climate variability are investigated and reviewed. Particularly El Niño/Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and ENSO Modoki are explored for their roles in the extreme events ranging from blistering summers to overflowing rivers. While the role of ENSO in extreme events is extensively studied and recognized, the role of other climate modes is not so well understood. Here, it is shown that IOD and ENSO Modoki are responsible for some of the extreme events even more than ENSO.

Prediction of extreme weather events two-to-six weeks ahead has immense social-economic benefits for hazard prevention and risk management as well as economic planning. Physical basis for such subseasonal prediction is primarily rooted in the intrinsic predictability of large-scale circulation associated with the tropical intraseasonal oscillation (ISO). Such prediction requires not only accurate prediction of tropical ISO and its teleconnection, but also the knowledge of how ISO modulates extreme weather events in the tropics and extratropics. This chapter provides a review of current knowledge on the modulation of ISO on many types of extreme weathers in the global tropics and extratropics including flooding, heavy snow storms, cold surges, hurricane and tropical storms, wild fire, aerosols, tornado and hail days, etc. This type of knowledge affords useful prediction tools for subseasonal prediction of extreme events if provided ISO can be realistically forecasted. Recent progress on subseasonal forecasts of tropical storm activity made by world major operational centers is also briefly reviewed and issues are discussed.

Climate services are becoming increasingly important due to increases in the frequency, intensity and exposure to weather and climate extremes, with stakeholders seeking to better manage their risks and opportunities. The El Niño-Southern Oscillation (ENSO) is one of the main contributing factors to Australia having one of the most variable climates in the world. High variability and climate change magnify the need for environmental intelligence to support weather and climate sensitive sectors such as agriculture, water management, emergency services and health. The Australian Bureau of Meteorology (Bureau) has been developing its climate services since the 1980s. These include data services, climate monitoring and prediction, climate advice and international activities, and are heavily reliant on strong information systems and research support. Services are delivered through a range of online products and tools as well as through briefings, training and social media platforms. The Bureau has shifted to user-centric delivery, and engages strongly with its user communities. Understanding user needs and decision-making processes informs the development of value-added products and services that can capture the full benefit of climate data, information, advice and research for our communities. In our journey of continuous improvement we are continuing to strive to better meet user needs. Having skilled and motivated staff with strong science and IT capability and a service ethic are essential. Improving science and modelling will also help close the gap between user needs and existing climate services. Fundamentally, success will depend on how well climate services assist users to improve their important decisions and the outcome of those decisions.

Strengthening the capacity of countries and communities to cope with the adverse effects of natural hazards and at the same time support development objectives requires investment in early warning; resilient infrastructure and financial risk transfer mechanisms. By shifting emphasis from hazard warnings to impact-based warnings, hazard, vulnerability and exposure information become central to all three components and can be used to improve the utility of each. A safe society depends on timely warning of the impact of a hazard, the ability to protect and transform lives and livelihoods, and the financial tools to recover quickly if losses are incurred.

The past few decades, have seen an increase in the intensity and frequency of weather and climate extremes around the world with severe impacts on several socio-economic sectors, especially in the developing world. Climate change impacts have increased due to enhanced greenhouse gas emissions and they undermine the ability of all countries to achieve sustainable development. In September 2015, the Member States of the United Nations adopted the new Sustainable Development Agenda, with 17 Sustainable Development Goals (SDGs). Climate services contribute directly to 11 SDGs through collection of climate data; generation and provision of a wide range of information on past, present and future climate; development of products to improve the understanding of climate and its impacts on natural and human systems; and the application of these data, information and products for decision-making in all socio-economic sectors affected by climate, at the global, regional and local scales. The Global Framework for Climate Services (GFCS) established by the World Climate Conference-3 in 2009, is enabling society to better manage the risks and opportunities arising from climate variability and change, through the development and incorporation of science-based climate information and prediction into planning, policy and practice. Climate Services in six socio-economic sectors i.e., Agriculture and Food Security, Disaster Risk Reduction, Health, Water, Energy and Tourism to promote sustainable development have been presented with suitable examples.

Climate change significantly impacts on the occurrence of natural disasters. However, regional impact assessment of climate change on severe weathers, hazards, and water resources is still limited by coarse resolution of global/general circulation models, limited applications of regional downscaling, and few impact assessment models. This chapter summarizes current activity of impact assessment of climate change around Japan and Southeast Asia based on the latest climate projection since the IPCC Fifth Assessment Report and on developed impact assessment models. This chapter mainly covers the future changes of heavy precipitation, river flooding, coastal flooding, and water resources around Japan and Southeast Asia.

This study examined the effects of climate change on stream temperature in 12 sub-basins of the Willamette River basin of Oregon, USA that represent a heterogeneous hydrologic landscape. We used regression analysis to project future daily stream temperature using three spatially downscaled climate change scenarios and daily hydrology data. Daily maximum stream temperature was best explained by a combination of the 15 day moving average of daily air temperature and daily streamflow. Together with a reduction in summer streamflow, rising air temperature may increase stream temperature 1–4°C by the 2080s. Stream temperature rises modestly in groundwater-fed streams in high elevations, illustrating that groundwater-fed streams could be more resilient to climate warming and reduced surface flow. In contrast, lowland surfacewater-fed streams that lack riparian vegetation will be most vulnerable to climate change since stream temperature is projected to increase most (up to 4°C) under the highest climate change scenario. Such changes will have negative consequences for cold-water fishes that are already listed as endangered species. The exceedance probability of threshold temperature (17.8°C and 21°C) increased substantially, particularly in the lowland areas, suggesting future management practices for threatened and endangered fish species should focus on improving thermal conditions in those reaches.

Contemporary flood forecasting frameworks are typically based on point discharge measurements at discrete locations; hence they are unable to provide spatio-temporal information of flood inundation extents over large scales and at high spatial resolution. The use of hydrologic/hydraulic models has recently appeared to be the most suitable option to bridge this gap. This chapter features coupling of a spatially distributed hydrologic model, Soil and Water Assessment Tool (SWAT), with a 2D hydraulic model LISFLOOD-FP, for flood inundation modeling over the Ohio River Basin, USA. Simulated 100-year return period flow outputs from SWAT are set at multiple input boundary locations of LISFLOOD-FP and routed along the streamlines to generate corresponding flood maps. Model evaluation shows that simulated daily streamflow from SWAT has Kling-Gupta and Nash-Sutcliffe Efficiency scores in the range of 0.4–0.72 when compared against observed records across the basin, and the modeled inundation area from LISFLOOD-FP has more than 70% agreement with the corresponding 100-year reference flood maps along the main river channels. While these results are promising, this chapter also reveals several avenues which can lead towards an integrated flood modeling framework having enhanced predictability.

Each month, the Australian Bureau of Meteorology issues operational seasonal streamflow forecasts of total water volumes for three months ahead for over 200 locations across Australia (http://www.bom.gov.au/water/ssf/). The forecasts are created using modelling approaches developed by the Commonwealth Scientific and Industrial Research Organisation, through a close and ongoing research partnership. Outcomes from the Seasonal Climate Research Program of the Bureau and hydrologic research conducted by the university sector in Australia have also directly contributed to the development and delivery of this service.

The publicly available forecasts are based on a statistical modelling approach that uses relationships from directly observed streamflow data and derived climate indices. Forecasts based on rainfall-runoff modelling forced by downscaled rainfall forecasts are currently being released to and evaluated by registered users.Work is underway to merge forecasts from these approaches to improve accuracy and reliability.

Delivery and development of the forecasting service requires cooperation with internal and external stakeholders, a comprehensive understanding of user needs, support for research and development, robust operational modelling tools and web-based service delivery systems, a communication and adoption strategy, and an implementation plan. This chapter discusses how these multiple elements are combined to provide a national seasonal streamflow forecasting service for Australia.

Droughts continue to be a major natural hazard. Areas around the world face a pressing question: Are we prepared for another major drought given the likelihood of a remarkably drier future, where the frequency and intensity of droughts falls far outside our contemporary experience? This question is complex since it involves many risk management issues beyond traditional crisis management, including the impact of climate change, the status of infrastructures, the role of institutions and behaviors, and the limiting factors of the use of drought forecasts. These issues must be studied in a holistic framework considering the interdependence among the social, economic, technical, and environmental factors that jointly challenge drought preparedness. This chapter provides discussion of these issues and synthesis of relevant studies. We expect to shed light on an integrated research agenda for drought preparedness, which is urgently needed for our society.

This paper introduces the priorities of the WMO Commission for Hydrology. The programme of work adopted by the Commission for the period 2013–2016 focuses on five thematic areas, namely Quality Management Framework — Hydrology; Data Operations and Management; Water Resources Assessment; Hydrological Forecasting and Prediction; and Water, Climate and Risk Management. In addition to the five thematic areas, the WMO Congress has tasked the Commission with contributing to several WMO priorities, including the Global Framework on Climate Services, the WMO Integrated Global Observing System, Disaster Risk Reduction and Capacity Development. The paper elaborates major activities within the theme area of Water, Climate and Risk Management. Chinese practices of hydrological forecasting and prediction for decision-making support to flood management is also presented. Thanks to the WMO’s efforts, collaboration between the water and climate communities has expanded in recent years. Climate products and services through the incorporation of hydrological observations have been improved. These advances, coupled with recent improvements in monthly to seasonal climate and hydroclimatic outlooks are beginning to yield improvements in hydrological services delivery, particular with respect to increased use of short-term climate forecasts and outlooks in water resources systems operations and seasonal planning. The paper will describe these issues and future direction associated with them.

This chapter explores the issue of handling climate uncertainty in strategic water planning with a focus on drought risk. It builds on the author’s work experience at the interface between climate science and water planning practice in Australia. This experience suggests that there is an ongoing disconnect between the academic literature and practice due to: differences in terminology owing to the different disciplines involved; an emphasis on accurate and precise prediction versus a preparedness and resilience paradigm that evolves to meet emerging threats; the perceived need to accurately characterise uncertainty versus the disempowering impacts of large levels of uncertainty and complexity on practical decision-making (which can lead to overly conservative decisions); and a lack of synthesis of climate adaptation research findings in terms of their implications for practical decision-making.