Roger Pulwarty

An Introduction to Trends in Extreme Weather and Climate Events: Observations, Socioeconomic Impacts, Terrestrial Ecological Impacts, and Model Projections*

Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.

Human Factors Explain the Increased Losses from Weather and Climate Extremes

Abstract Societal impacts from weather and climate extremes, and trends in those impacts, are a function of both climate and society. United States losses resulting from weather extremes have grown steadily with time. Insured property losses have trebled since 1960, but deaths from extremes have not grown except for those due to floods and heat waves. Data on losses are difficult to find and must be carefully adjusted before meaningful assessments can be made. Adjustments to historical loss data assembled since the late 1940s shows that most of the upward trends found in financial losses are due to societal shifts leading to ever—growing vulnerability to weather and climate extremes. Geographical locations of the large loss trends establish that population growth and demographic shifts are the major factors behind the increasing losses from weather—climate extremes. Most weather and climate extremes in the United States do not exhibit steady, multidecadal increases found in their loss values. Without majo...

A U.S. Clivar project to assess and compare the responses of global climate models to drought-related SST forcing patterns: Overview and results

Abstract The U.S. Climate Variability and Predictability (CLIVAR) working group on drought recently initiated a series of global climate model simulations forced with idealized SST anomaly patterns, designed to address a number of uncertainties regarding the impact of SST forcing and the role of land–atmosphere feedbacks on regional drought. The runs were carried out with five different atmospheric general circulation models (AGCMs) and one coupled atmosphere–ocean model in which the model was continuously nudged to the imposed SST forcing. This paper provides an overview of the experiments and some initial results focusing on the responses to the leading patterns of annual mean SST variability consisting of a Pacific El Nino–Southern Oscillation (ENSO)-like pattern, a pattern that resembles the Atlantic multidecadal oscillation (AMO), and a global trend pattern. One of the key findings is that all of the AGCMs produce broadly similar (though different in detail) precipitation responses to the Pacific for...

Reframing disaster policy: the global evolution of vulnerable communities

The Social Construction of Disaster Disaster is widely perceived as an event beyond human control. The capricious hand of fate has moved against unsuspecting human communities, creating massive destruction and despair.[i] The sudden randomness of the event accentuates the cruelty of its effects, as surely the victims would have acted differently, had they known the risk. Other nations and organizations rush humanitarian aid to rebuild damaged communities, but stop short of examining the policies and practices that contributed to the event.

Climate and Salmon Restoration in the Columbia River Basin: The Role and Usability of Seasonal Forecasts

Abstract The Pacific Northwest is dependent on the vast and complex Columbia River system for power production, irrigation, navigation, flood control, recreation, municipal and industrial water supplies, and fish and wildlife habitat. In recent years Pacific salmon populations in this region, a highly valued cultural and economic resource, have declined precipitously. Since 1980, regional entities have embarked on the largest effort at ecosystem management undertaken to date in the United States, primarily aimed at balancing hydropower demands with salmon restoration activities. It has become increasingly clear that climatically driven fluctuations in the freshwater and marine environments occupied by these fish are an important influence on population variability. It is also clear that there are significant prospects of climate predictability that may prove advantageous in managing the water resources shared by the long cast of regional interests. The main thrusts of this study are 1) to describe the cli...

Hell and High Water: Practice-Relevant Adaptation Science

Adaptation requires science that analyzes decisions, identifies vulnerabilities, improves foresight, and develops options. Informing the extensive preparations needed to manage climate risks, avoid damages, and realize emerging opportunities is a grand challenge for climate change science. U.S. President Obama underscored the need for this research when he made climate preparedness a pillar of his climate policy. Adaptation improves preparedness and is one of two broad and increasingly important strategies (along with mitigation) for climate risk management. Adaptation is required in virtually all sectors of the economy and regions of the globe, for both built and natural systems (1).

Toward global drought early warning capability: Expanding international cooperation for the development of a framework for monitoring and forecasting

Drought is a global problem that has far-reaching impacts, especially on vulnerable populations in developing regions. This paper highlights the need for a Global Drought Early Warning System (GDEWS), the elements that constitute its underlying framework (GDEWF), and the recent progress made toward its development. Many countries lack drought monitoring systems, as well as the capacity to respond via appropriate political, institutional, and technological frameworks, and these have inhibited the development of integrated drought management plans or early warning systems. The GDEWS will provide a source of drought tools and products via the GDEWF for countries and regions to develop tailored drought early warning systems for their own users. A key goal of a GDEWS is to maximize the lead time for early warning, allowing drought managers and disaster coordinators more time to put mitigation measures in place to reduce the vulnerability to drought. To address this, the GDEWF will take both a top-down approach...

Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation: Managing the Risks from Climate Extremes at the Local Level

Disasters are most acutely experienced at the local level (high agreement, robust evidence). The reality of disasters in terms of loss of life and property occurs in local places and to local people. These localized impacts can then cascade to have national and international consequences. In this chapter, local refers to a range of places, social groupings, experience, management, institutions, conditions, and sets of knowledge that exist at a sub-national scale. [5.1] Developing strategies for disaster risk management in the context of climate change requires a range of approaches, informed by and customized to specific local circumstances (high agreement, robust evidence). These differences and the context (national to global, urban to rural) in which they are situated shape local vulnerability and local impacts. [5.1] The impacts of climate extremes and weather events may threaten human security at the local level (high agreement, medium evidence). Vulnerability at the local level is attributed to social, political, and economic conditions and drivers including localized environmental degradation and climate change. Addressing disaster risk and climate extremes at the local level requires attention to much wider issues relating to sustainable development. [5.1] While structural measures provide some protection from disasters, they may also create a false sense of safety (high agreement, robust evidence). Such measures result in increased property development, heightened population density, and more disaster exposure. Current regulations and design levels for structural measures may be inadequate under conditions of climate change.

Scenarios for vulnerability: opportunities and constraints in the context of climate change and disaster risk

Most scientific assessments for climate change adaptation and risk reduction are based on scenarios for climatic change. Scenarios for socio-economic development, particularly in terms of vulnerability and adaptive capacity, are largely lacking. This paper focuses on the utility of socio-economic scenarios for vulnerability, risk and adaptation research. The paper introduces the goals and functions of scenarios in general and reflects on the current global debate around shared socio-economic pathways (SSPs). It examines the options and constraints of scenario methods for risk and vulnerability assessments in the context of climate change and natural hazards. Two case studies are used to contrast the opportunities and current constraints in scenario methods at different scales: the global WorldRiskIndex, based on quantitative data and indicators; and a local participatory scenario development process in Jakarta, showing a qualitative approach. The juxtaposition of a quantitative approach with global data and a qualitative-participatory local approach provides new insights on how different methods and scenario techniques can be applied in vulnerability and risk research.

The Hadley and Walker Regional Circulations and Associated ENSO Impacts on South American Seasonal Rainfall

While numerous detailed studies have been conducted of the annual cycle of convection over other regions (e.g., the Asian summer monsoon and the West African summer monsoon regions), the annual cycle and its modulation in the tropical South American region has received attention only relatively recently. Most of the annual total rainfall observed over tropical South America occurs during the austral summer and autumn months. The large-scale meteorological systems that modulate rainfall during these periods are linked to the strength and movement of large-scale climatological features—in particular, the Intertropical Convergence Zone (ITCZ) and the South Atlantic Convergence Zone (SACZ). It is well known that the anomalous patterns related to the El Nino/Southern Oscillation (ENSO) influence the ITCZ and SACZ patterns, with strong interan-nual and seasonal variations over tropical and subtropical South America.