World Health Day 2008 10 Extreme Weather Events


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  • This slide summarizes the topics this module will address. The module moves to a consideration of the potential health impact attributable to climate change from changes in the frequency/severity of extreme weather events in stages. First the module summarizes how these events threaten public health and reviews the magnitude of past public health impacts from these events. Factors other than climate change that influence the health impacts of these events are reviewed before considering the anticipated changes in risk from these events that may be attributable to climate change and whether/how adaptation could help limit any future anticipated increase in associated health impacts.
  • Countries in the South East Asia region with low-lying islands, extended coastal areas, mountains and large river basins have a history of experiencing a wide range of extreme weather events.
  • The first cyclone of the 2008 season in the northern Indian Ocean was a devastating one for Myanmar. The category 4 cyclone killed more than 84,530 persons and over 53,000 were reported missing. In the areas affected, two-thirds of health facilities suffered some damage. One out of five was totally destroyed. Most of them were small, rural primary care centres. The estimated cost for rebuilding health facilities was estimated at US$2 billion. After the cyclone, 60% of people had no access to clean water as traditional sources of water in villages became contaminated with seawater. In addition, many water sources became polluted due to the breakdown of sanitation facilities in the flooded areas The average reported number of deaths per household was 2.2 whereby 66% of the victims were women. The most significant health need was support for psychological stress: 23% of people reported psychological problems after the cyclone.
  • This is an example of a relatively common type of photo in Bangladesh with residents trying to cope with either floods or cyclone-related flooding. The frequency of this type of impact from extreme weather events does not diminish from its direct and indirect health risks. In particular, this type of flooding challenges water purification and delivery systems, creates sanitation problems, and severely hampers the provision of aid.
  • While countries in South East Asia experience a wide range of extreme weather events there is a smaller group of these events that has had and will likely continue to have a disproportionate health impact and be a focus of research and adaptation efforts focused on understanding and controlling public health risks and impacts. This group includes cyclones, extreme precipitation/floods, wildfires and thermal extremes (addressed in a separate presentation).
  • The health impacts of an extreme event are not defined by mere occurrence of an event. Instead, they are determined to a large extent by physical factors that define the event and how it is experienced by exposed populations. In addition, while there may be general differences in these factors between categories of extreme weather events, the differences between individual events are equally important in evaluating the source and nature or the associated health risks and impacts. In short, from a public health perspective, not all extreme weather events are equal.
  • This slide presents trends in the number of all disasters compared to earthquakes and then the number of floods and cyclones combined compared to earthquakes. Earthquakes are not sensitive to climate change so the increase in all disasters and floods and cyclones relative to earthquakes is suggestive that climate change may play some role in the increase. This is not conclusive, as noted in the text for the figures changes in reporting non-earthquake disasters may also play a role, but another indication of potential increased future risk as a result of climate change.
  • In addition to the importance of physical characteristics, an event’s public health risk and impact is shaped by the characteristics of the affected population. In general, any characteristic that limits the ability of individuals or communities to respond to or prepare for an extreme event’s conditions will increase public health risks. In addition, the chance for large numbers of adverse health impacts clearly will increase with the size of the exposed population exposed, all else equal. Wealth is an especially important social factors to address because it can affect exposure conditions and duration during and after the event (e.g., presence of floodwaters with a cyclone). In addition wealth clearly affects individual’s and communities access/ability to redirect resources to address adverse conditions.
  • Direct health impacts of an extreme event are characterized by the outcomes that are clearly attributable to the event itself (e.g., drowning from a cyclone). These impacts typically provide the information that is subsequently used to describe the event (e.g., so many dead and so many hospitalized). Mental health impacts of extreme weather events are increasingly being recognized as a significant category of direct health impacts.
  • Indirect health impacts result from the conditions left behind from the extreme weather event. Most importantly, these can be health impacts associated with a loss of shelter and loss of access to food and clean sources of water. One could argue about the criteria for distinguishing between direct and indirect effects for any category of extreme weather events or for a specific event. However, the more important point is that these additional types of “follow-on” impacts not be overlooked when considering the public health burden of an individual extreme weather event or category of events or in preparing for future events.
  • This slide highlights some key issues to remember as the focus of the module shifts to evaluating current and potential future health impacts of extreme weather events in South East Asia. Most importantly, extreme weather events are already a fact of life in countries of South East Asia. The region regularly experiences a wide range of these events and has a history of them resulting in catastrophic health impacts. The module will typically present data that focuses on lives lost in these events. However, this is only one component of the health impact of these events as they typically also have an even larger morbidity impact in terms of the number of people affected. Finally, in reviewing the information it will be important to remember that not all extreme weather events have the same health impact and to try and understand what role specific notable events play in influencing impacts that are presented as either a total or average over time. Each of these points will be emphasized in following slides.
  • These results, developed using data from the EMDAT database (EMDAT, 2008) highlight several important elements about the health impacts, as reflected by reported deaths, from extreme weather events in South East Asia. The main conclusions from this data are: The region has a high vulnerability to extreme weather events based on estimates of associated mortality The mortality impacts are not evenly distributed across the types of events or across countries even when differences in population are accounted for Storms and floods account for the vast majority of the reported mortality.
  • This slide presents a summary of the data from the previous slide showing the extreme weather event related mortality from 1970-2008 by country. Based on this period, Bangladesh, India, and Myanmar would be highlighted as countries with the highest vulnerability to extreme weather events within this group. However, it is worth noting that because of the relative magnitude of the impacts in these countries in other countries in South East Asia appear in this figure as though they have had no impacts when in most cases the total mortality from these events over this period is reported in terms of thousands of deaths (Bhutan and Timor Leste excluded). Finally, it is worth noting that Myanmar’s relative importance in this figure is solely the result of cyclone Nargis in 2008 which is estimated to be responsible for over 138,000 deaths. This highlights the earlier discussion of the importance of single events in summarizing the health impacts of extreme weather events and raises a “who might be next” question for the countries in the region.
  • This is yet another presentation of the earlier summary data on lives lost to extreme weather events in countries of in South East Asia from 1970-2008. This slide focuses on the distribution of the lives lost in the region during this period according to the type of event. The slide highlights the clear domination of this impact data by storm events followed by floods and then extreme temperatures. These three categories of events all have clear ties to physical processes that raise the possibility of increased frequency and/or severity of future events as a result of climate change. Specifically, storms are linked to warming sea surface temperatures, floods to increased evaporation and ultimately precipitation as a result of warmer temperatures, and extreme high temperature events with the anticipated warming.
  • The goal of this slide is to again draw attention to the fact that health impacts from extreme weather events are highly variable over time and may have only a weak correlation with the absolute intensity of an event. More generally this observance highlights that any estimates of future health impacts from extreme weather events are likely to be highly uncertain because of all the non-meteorological factors that affect health impact totals and the importance of single events in summaries of impacts over time.
  • An example of how understanding the actual data on health impacts provides greater context when summary or “average” figures are presented. In this slide, showing deaths from hurricanes with U.S. landfalls from the year 1900 and the period 1940-2007 there are two significant years, 1900 and 2005, when total deaths are in excess of 2,000 (note the logarithmic y-axis scale). In all other years the totals are greatly lower. These two years dominate estimates of averages and reported totals. Even these data partially obscure the impact of single events though because mortality is summed across all events within a year. In some cases totals represent relatively small impacts across a number of events. At the extreme, the value shown for 1900 of 8,000 lives lost is solely for the hurricane that struck Galveston, Texas. The main conclusion from this example is that within the category of extreme weather events there is not all events are equal in terms of their health risks and impacts and that there is a further subset of events that drive health impact results.
  • This slide highlights the importance of single events in the mortality data for extreme weather events in the countries of in South East Asia. The goal of this slide is to consider the factors that contributed to the high mortality totals from these discrete events in relation to predicted trends both for the underlying extreme weather events and for the vulnerable populations when considering the potential future impact of these events that would be attributable to climate change.
  • Cartograms provide one option for visually presenting the distribution of a variable of interest over multiple countries. Specifics of the methods and approaches used in the cartograms on the following slides are available from the WorldMapper website (see
  • This cartogram provides a current impacts baseline for consideration as it reweights country areas based on the size of their populations. For the South East Asia region note the size of India and Bangladesh compared to traditional land area-based maps. For an overall sense of how cartograms function compare the areas of China and Russia compared to a traditional land-mass based presentation.
  • This cartogram has reweighted country sizes based on data for flood related deaths. For contrast compare the flooding results for India, Bangladesh, and the United States with the population weighted areas on the previous slide. These results highlight that several in countries of South East Asia are highly vulnerable to flooding.
  • Smoke from agricultural and forest fires burning on Sumatra (left) and Borneo (right) in late September and early October 2006 blanketed a wide region with smoke that interrupted air and highway travel and pushed air quality to unhealthy levels. This image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on October 1, 2006, shows places where MODIS detected actively burning fires marked in red. Smoke spreads in a gray-white pall to the north. As a result of these fires, air quality was degraded across the region including SEARO members Thailand and Malaysia. This degraded air quality also provides an example of how extreme weather events can have indirect health impacts far from and/or long after the events themselves end.
  • This slide again highlights that climate change-based predictions about the nature of future extreme events are only part of the information that is needed to accurately estimate the associated change in future health impacts. More specifically, while some socio-demographic changes over time can be forecast with some precision (e.g., populations, age distribution) others are much more difficult to predict (e.g., health status, wealth) and these factors are critical to health impact estimation. In particular, because the poor most often bear a disproportionate share of health impacts relevant questions will include how many poor are there, where are they located, and what is their standard of living. The last is particularly important noting that poverty can be based on both relative and absolute measures and that improving the quality of life of the poor over time may also provide health benefits. The role of adaptation must also be recognized and accounted for in predicting future health outcomes. The difficulty with this element is in drawing conclusions about what the pressure for adaptation will be, how much of that demand may be driven by climate change, and how effective any adaptive responses will be in addressing future extreme weather events.
  • Because extreme weather events are already a part of life in countries of in South East Asia climate change will not be introducing a new category of health risks to the region’s populations. In addition, the historical variation in the frequency and intensity of these events means that while it may be possible to identify marginal changes in the characteristics of these events that can be attributed to climate change. However this variation makes it extremely unlikely that researchers will be able review a series of events over time and say that any one was solely attributable to climate change. The implications of this complicate identifying the marginal health impacts of climate change on these events based on a history of impacts where totals are skewed to individual events and the elements of where an event occurs and who experiences it are as important to determining health impacts as the actual physical characteristics of the event itself.
  • This highlights an adaptive response to a health risk of extreme weather events, building shelters. These shelters have been extremely successful in helping to limit deaths from cyclones following their construction. This highlights the possibility for adaptation to both reduce the vulnerability of at-risk populations and to limit the number and severity of adverse health impacts from extreme weather events. However, this picture also highlights how the effectiveness of adaptive measures can be constrained by available resources as it was noted that while the shelter can hold 400 it is located a town of 15,000. In this case, if everyone at risk from the event assumes they can utilize the shelter risks from future events could actually be increased if other options for reducing exposure are ignored.
  • Developing effective adaptive responses for extreme weather events requires vulnerable populations to understand the nature of the health risks they face. To the extent response plans are developed/modified for these events as a result of climate change they need to be carefully considered and address the full suite of potential health impacts of the events. Health authorities would benefit much form coordinating action with Red Crescent/Red Cross and other engaged disaster assistance organizations.
  • Effective notification and response plans should be viewed as ever-evolving plans that attempt to respond to changing conditions while drawing on lessons learned from past experience and practices. With clearly defined objectives these plans also can allow for flexible execution of tasks during actual events. This allows for the main objective, protection of public health, to be continuously pursued while recognizing and accounting for unanticipated changes in actual conditions. Finally, there should be a clear means for receiving, accepting, and implementing, offers of outside assistance during extreme events as these offers may help address critical resource constraints and improve public health.
  • This photo shows Thai air force personnel loading a C130 military transport aircraft with aid following cyclone Nargis. Outside assistance may provide critical resources that can help significantly improve public health following an extreme weather event.
  • This slide notes that while extreme weather events are already an element of living in SEA region countries climate change has the potential to increase the overall risk of those events by increasing their frequency and/or severity. Further, this risk should be recognized while understanding that natural variability is likely to limit the ability to specifically identify marginal changes in any one event or identification of a specific event as a “climate change induced” event.
  • Predicting net health impacts from changes in future extreme events attributable to climate change is, and will continue to be, extremely difficult because of the need to simultaneously account for multiple factors that are related to varying degrees. This difficulty also reflects the current situation where the health impacts of these events over time are driven largely by single events. The ability to predict this subset of truly catastrophic extreme weather events has not yet been developed.
  • Climate change will increase the risk from extreme weather events in countries of South East Asia. Addressing this change in risk proactively should be seen as a priority because of the uncertainty over future impacts and the history of catastrophic events in the recent past. Recommended reading: 2007 IPCC reports: The Physical Science Basis, FAQ 3.3 page 107 and FAQ 9.1 p 119
  • World Health Day 2008 10 Extreme Weather Events

    1. 1. Protecting our Health from Climate Change: a Training Course for Public Health Professionals Chapter 10: Extreme Weather Events
    2. 2. Overview: This Module <ul><li>Categories of extreme weather events considered </li></ul><ul><li>How extreme weather events threaten public health </li></ul><ul><li>Nature of public health impacts with extreme weather events </li></ul><ul><li>Current health risks and impacts from extreme weather events in South East Asia </li></ul><ul><li>Future risks and potential health impacts from climate change </li></ul><ul><li>Conclusions </li></ul>
    3. 3. Extreme Weather Events Considered <ul><li>All extreme weather events currently experienced in countries of South East Asia could be affected by climate change </li></ul><ul><ul><li>Typhoons </li></ul></ul><ul><ul><li>Floods </li></ul></ul><ul><ul><li>Precipitation extremes </li></ul></ul><ul><ul><li>Wildfires </li></ul></ul><ul><ul><li>Temperature extremes </li></ul></ul><ul><ul><li>Others (windstorms, blizzards, etc.) </li></ul></ul>
    4. 4. Example: Cyclone Nargis Hits Myanmar in 2008 New York Times, 2008 The Guardian, 2008
    5. 5. Example of Flooding: Bangladesh 2004 Residents with food during a 2004 flood in Bangladesh BSA-UA, 2004
    6. 6. Extreme Weather Events Considered <ul><li>Focus on typhoons/cyclones, extreme precipitation/floods, and wildfires because </li></ul><ul><ul><li>They pose a significant health risk </li></ul></ul><ul><ul><li>They have a long history of substantial adverse health impacts </li></ul></ul><ul><ul><li>They are the focus of considerable climate change-related research </li></ul></ul><ul><ul><li>They are a focus of current adaptation efforts </li></ul></ul>
    7. 7. How Extreme Weather Events Threaten Public Health <ul><li>The health risks/impacts of an extreme weather event are a function of: </li></ul><ul><ul><li>Severity: how challenging are the event’s conditions (e.g., cyclone winds over 120 mph) </li></ul></ul><ul><ul><li>Duration: how long are the extreme conditions experienced </li></ul></ul><ul><ul><li>Surprise: how much advance warning was available for the event (e.g., days, hours, minutes) </li></ul></ul><ul><li>There are differences in categories of events </li></ul><ul><li>There will be differences between individual events within a category </li></ul>
    8. 8. Global Warming in Increasing the Risk of Extreme Weather Events
    9. 9. Population Characteristics Affect Risks/Impacts of Extreme Weather <ul><li>Population factors affecting the risks/impacts of extreme weather events include </li></ul><ul><ul><li>Size: how many people does the event affect </li></ul></ul><ul><ul><li>Age: the young and old are less able to help themselves in an extreme weather event </li></ul></ul><ul><ul><li>Health status: poor health limits individuals’ response ability </li></ul></ul><ul><ul><li>Wealth: poverty can limit the types of preparation actions and responses that can be considered, it can also affect exposure (e.g., housing stock) </li></ul></ul>
    10. 10. Types of Public Health Impacts from Extreme Weather Events <ul><li>Direct health impacts </li></ul><ul><ul><li>Morbidity </li></ul></ul><ul><ul><li>Mortality </li></ul></ul><ul><ul><ul><li>Both are observable and clearly attributable to the physical impacts of the event: </li></ul></ul></ul><ul><ul><li>Mental health impacts (Post Traumatic Stress Disorder-PTSD, depression) </li></ul></ul><ul><ul><ul><li>Delayed onset and recognition can lead to impacts being missed in an event summary </li></ul></ul></ul><ul><ul><ul><li>Potential to adversely affect productivity </li></ul></ul></ul><ul><ul><ul><li>Potential for severe health and quality of life impacts </li></ul></ul></ul>
    11. 11. Nature of Public Health Impacts with Extreme Weather Events <ul><li>Indirect health impacts </li></ul><ul><ul><li>Can be less observable </li></ul></ul><ul><ul><li>Can take time to develop </li></ul></ul><ul><ul><li>May reflect a loss of access to critical resources: clean water, shelter </li></ul></ul><ul><ul><li>Can result from disruption to routines: </li></ul></ul><ul><ul><ul><li>Restricted access to, or supply of, medicine, caregivers, medical facilities </li></ul></ul></ul>
    12. 12. Overview of Extreme Weather Event Health Impacts <ul><li>Extreme weather events have a history of significant health impacts in many Asian countries </li></ul><ul><li>Impact summaries focus on mortality but significant morbidity is associated with the underlying events </li></ul><ul><li>Totals and “average” event impacts obscure the skewed nature of the impacts data </li></ul><ul><ul><li>Results can be driven by impacts of a single event </li></ul></ul><ul><ul><li>Impacts from repeated, smaller events can be as significant as a major extreme event </li></ul></ul>
    13. 13. Deaths from Extreme Weather Events 1970-2008: Example South East Asia Impacts not equally distributed by country or type of extreme event. Nearly 800,000 reported deaths. Storm mortality 84% of total. EMDAT, 2008
    14. 14. Mortality from Extreme Weather: Example South East Asia Bangladesh is the key to mortality impacts to SEARO from extreme weather events EMDAT, 2008
    15. 15. Health Impacts by Type of Extreme Event: Example South East Asia This graph highlights the relative importance of storms EMDAT, 2008
    16. 16. Importance of Single Events in Health Impacts of Extreme Weather Events <ul><li>While appropriate to summarize health impacts of extreme weather events it would be inappropriate to try and convey a sense of “average” impacts over time </li></ul><ul><li>These events have extremely variable health impacts </li></ul><ul><li>Totals are driven by a few events </li></ul><ul><li>The strongest events may not have the highest health impact </li></ul>
    17. 17. Distribution of Health Impacts by Event: U.S. Hurricane Deaths U.S. hurricane death totals are driven by single storm impacts Deaths per year from hurricanes Mills, 2009
    18. 18. Importance of Single Extreme Weather Events in South East Asia <ul><li>73% of all reported extreme weather event deaths, roughly 77,000, in countries of South East Asia from 1970-2008 are from three cyclones </li></ul><ul><ul><li>November, 1970 (unnamed): 300,000 killed in Bangladesh </li></ul></ul><ul><ul><li>April, 1991 (Gorky): 139,000 killed in Bangladesh </li></ul></ul><ul><ul><li>May, 2008 (Nargis): 137,500 killed in Myanmar </li></ul></ul>EMDAT, 2008
    19. 19. Current Mortality Impacts of Flooding: Cartogram Results <ul><li>Cartograms </li></ul><ul><ul><li>Re-weight a country’s land area as a percentage of the variable in question </li></ul></ul><ul><ul><li>For health outcomes </li></ul></ul><ul><ul><ul><li>Larger countries/regions account for more of the health impact in question (e.g., deaths from a cause or cases of an illness) </li></ul></ul></ul><ul><ul><ul><li>For evidence of a relatively high or disproportionate impacts compare cartograms for the health outcome with cartograms of population </li></ul></ul></ul>
    20. 20. Cartogram Baseline Now: World Population in 2000 Countries’ areas are re-weighted according to the size of its population: note India and China Worldmapper, 2008a
    21. 21. Relative Importance of Floods in SEARO as a Mortality Risk Worldmapper, 2008d SEARO historically vulnerable to flooding. Note increased size of India and Bangladesh.
    22. 22. Smoke from Forest and Agricultural Fires in 2006, 2006 Fire from smoke results in degraded air quality in Indonesia, Malaysia and Thailand
    23. 23. Climate Change and Future Health Impacts of Extreme Weather Events <ul><li>Increase in risk may or may not result in increased health impacts from future extreme weather events </li></ul><ul><ul><li>Sensitivity of health impact totals to single events means marginal impacts could have either a minimal or significant health impact </li></ul></ul><ul><ul><li>Socio-demographic changes in population location, size, health, wealth likely as significant as impact of climate change on event’s future health impact </li></ul></ul><ul><ul><li>Adaptation, in the form of hazard planning, preparation, and response, will play a critical role in determining the magnitude of future health impacts from extreme weather events </li></ul></ul>
    24. 24. Caveats to Climate Change and Extreme Weather Events <ul><li>The impact of climate change on extreme weather events will best be measured in terms of changes in frequency and intensity of events </li></ul><ul><li>These are likely to be marginal changes </li></ul><ul><li>It is extremely unlikely that a day will come when a single event can be attributed, in its entirety to climate change </li></ul>
    25. 25. Examples of Adaptation to Extreme Weather Events Following devastating cyclones Bangladesh has begun constructing cyclone shelters to keep vulnerable residents safe Pitchford, 2008
    26. 26. Goals for Extreme Weather Event Notification and Response Plans <ul><li>Improve public understanding of the magnitude and severity of the risks involved </li></ul><ul><li>Develop plans for reducing public exposure to the event’s conditions </li></ul><ul><ul><li>Evacuation options </li></ul></ul><ul><ul><li>Shelters </li></ul></ul><ul><li>Prepare response plans with clearly defined goals and responsibilities </li></ul><ul><li>Do not overlook planning for indirect health impacts, they can be significant </li></ul><ul><li>Health sector to be represented and to participate actively in national climate change committees </li></ul>
    27. 27. Goals for Extreme Weather Event Notification and Response Plans (cont.) <ul><li>Develop hypothetical scenarios and practice (i.e., tabletop exercises) </li></ul><ul><li>Draw on past experience </li></ul><ul><li>Be flexible in response to unanticipated constraints and opportunities during actual events </li></ul><ul><li>Be open to outside assistance that has the potential to improve public health </li></ul>
    28. 28. Extreme Weather Event Response: Providing/Receiving Assistance The Guardian, 2008
    29. 29. Conclusions <ul><li>Extreme weather events already present a significant health risk to countries in South East Asia based on a history of significant impacts </li></ul><ul><li>Climate change may increase the frequency and/or severity of many of those events, </li></ul><ul><ul><li>Storms/cyclones </li></ul></ul><ul><ul><li>Flooding </li></ul></ul><ul><li>Detecting the climate change signal or marginal impact in any given event may be impossible given natural variation </li></ul>
    30. 30. Conclusions (cont.) <ul><li>Ultimate health impact of extreme events with climate change is uncertain </li></ul><ul><ul><li>Totals driven mainly by a limited number of individual events </li></ul></ul><ul><li>Changes in factors other than climate change will also be critical in determining the nature and extent of future health impacts </li></ul><ul><ul><li>Population size, health, wealth, location </li></ul></ul><ul><li>Effective adaptation (e.g., education, notification, and response plans) could limit future adverse health impacts </li></ul>
    31. 31. Conclusions (cont.) <ul><li>Uncertainty over future arguments is not an argument for doing nothing </li></ul><ul><li>Uncertainty with anticipated increase in risk from the nature of the events argues for increased efforts to prepare for future extreme weather events </li></ul>