Executive Summary

The severity of the impacts of extreme and non-extreme weather and climate events depends strongly on the level of vulnerability and exposure to these events (high confidence). [2.2.1, 2.3, 2.5] Trends in vulnerability and exposure are major drivers of changes in disaster risk, and of impacts when risk is realized (high confidence). [2.5] Understanding the multi-faceted nature of vulnerability and exposure is a prerequisite for determining how weather and climate events contribute to the occurrence of disasters, and for designing and implementing effective adaptation and disaster risk management strategies. [2.2, 2.6]

Vulnerability and exposure are dynamic, varying across temporal and spatial scales, and depend on economic, social, geographic, demographic, cultural, institutional, governance, and environmental factors (high confidence). [2.2, 2.3, 2.5] Individuals and communities are differentially exposed and vulnerable and this is based on factors such as wealth, education, race/ethnicity/religion, gender, age, class/caste, disability, and health status. [2.5] Lack of resilience and capacity to anticipate, cope with, and adapt to extremes and change are important causal factors of vulnerability. [2.4]

Extreme and non-extreme weather and climate events also affect vulnerability to future extreme events, by modifying the resilience, coping, and adaptive capacity of communities, societies, or social-ecological systems affected by such events (high confidence). [2.4.3] At the far end of the spectrum – low-probability, highintensity events – the intensity of extreme climate and weather events and exposure to them tend to be more pervasive in explaining disaster loss than vulnerability in explaining the level of impact.

Context

This Summary for Policymakers presents key findings from the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). The SREX approaches the topic by assessing the scientific literature on issues that range from the relationship between climate change and extreme weather and climate events (‘climate extremes’) to the implications of these events for society and sustainable development. The assessment concerns the interaction of climatic, environmental, and human factors that can lead to impacts and disasters, options for managing the risks posed by impacts and disasters, and the important role that non-climatic factors play in determining impacts. Box SPM.1 defines concepts central to the SREX.

The character and severity of impacts from climate extremes depend not only on the extremes themselves but also on exposure and vulnerability. In this report, adverse impacts are considered disasters when they produce widespread damage and cause severe alterations in the normal functioning of communities or societies. Climate extremes, exposure, and vulnerability are influenced by a wide range of factors, including anthropogenic climate change, natural climate variability, and socioeconomic development (Figure SPM.1). Disaster risk management and adaptation to climate change focus on reducing exposure and vulnerability and increasing resilience to the potential adverse impacts of climate extremes, even though risks cannot fully be eliminated (Figure SPM.2). Although mitigation of climate change is not the focus of this report, adaptation and mitigation can complement each other and together can significantly reduce the risks of climate change. [SYR AR4, 5.3]

Introduction

The Energy Modeling Forum (EMF) has facilitated the development of integrated assessment models of economic activity and the resulting anthropogenic emissions, the relevant Earth system responses to the forcings from these emissions, and the costs of policies to mitigate anthropogenic emissions. Initially these integrated assessment models focused solely on the market impacts of climate change. EMF has been a leader in developing cross-disciplinary interactions between integrated assessment modelers and health researchers, with the result that some of the recent developments in population health models arose from the EMF workshops held in Snowmass. The appropriate and robust incorporation of health impacts into integrated assessment models will help policymakers visualize the dimensions of the possible health impacts of climate change and will inform the design of climate and adaptation policy responses.

The current burden of disease due to environmental factors is considerable (WHO, 2002). If trends continue, climate change is very likely to increase the burden of climate-sensitive diseases, including morbidity and mortality due to temperature extremes, extreme weather events (i.e., floods and droughts), air pollution, food- and water-borne diseases, and vector- and rodent-borne diseases; some of these relationships are better understood than others (McMichael et al., 2001). Climate change is one of many factors that will affect the burden of these health outcomes. Significant changes are expected to continue to occur in major factors determining population health, such as per capita income, provision of medical care, obesity, and access to adequate nutrition, clean water, and sanitation.

Introduction

Future global environmental exposures may be significantly different from those experienced in the past. Forecasting and preparing for the resultant potential ecological, social and population health impacts requires innovative and interdisciplinary research approaches, both to advance global change/health science and to contribute to informed policy decisions. These approaches include empirical analyses and scenario-based exposure modelling to achieve meaningful risk assessments of the potential impacts of climate and ecological changes. This chapter focuses on the application of epidemiology (an empirically based discipline) to understanding the potential health consequences of global environmental change. The empirical knowledge gained from epidemiological studies should be used iteratively with model development to strengthen the foundation of predictive models.

Epidemiological research can be used in the three domains introduced in Chapter 1: first, historical analogue studies to help understand current vulnerability to climate-sensitive diseases (including contributions to understanding the mechanisms of effects) and to forecast the health effects of exposures similar to those in the analogue situation; second, studies seeking early evidence of changes in health risk indicators or health status occurring in response to actual environmental change; and third, using existing empirical knowledge and theory to develop empirical-statistical or biophysical models of future health outcomes in relation to defined scenarios of change. This chapter discusses some standard epidemiological methods used to generate quantitative estimates of exposure–disease associations for studies in these three domains. The examples focus primarily on climate variability and change to maintain consistency throughout the discussion.