Hi, it's Mary Sheehan back and we're going to talk now about vulnerability, and why that is such an important concept when we're thinking about how to protect people's health in a changing climate. So, will everywhere be affected equally or in the same way by climate change? We know the risks of certain climate health impacts are greater for some individuals and for some cities. For example, the man in the photo was at risk, perhaps of drowning, perhaps of injury, or other kinds of impacts because he was physically located in the flood zone in the city when monsoon rains struck, and the city was at risk because it is in a part of India subject to those monsoon rains. In addition, we would also like to ask well, how can we protect those most vulnerable and at greatest risk? What tools do individuals and cities have and how do we build and strengthen those tools? An umbrella as this man has may be helpful, but it's probably not the most useful tool to deal with a flood that this man faces. So, this is really at the heart of how we will be thinking about the challenges of impacts of a changing climate on health. But let's start by defining vulnerability. The IPCC defines it as simply the propensity or predisposition to be adversely affected, and so, here in the photo, you see some polar bears. The poster species for climate change, and in this photo, we recognize two kinds of vulnerability. First, there's a baby polar bear there with its mother and like a human baby, we see intuitively, this is a life stage that's more sensitive to harm due to early development of the baby, lack of experience, smaller body size, dependence on adults, and many other factors. In the case of polar bears, a second source of vulnerability is that the species itself has a propensity to be adversely affected by its dependence on a habitat that's changing with a rapidly warming Arctic. So, this has to do with where polar bears live and what climate hazards they're exposed to. So, we start with a definition of vulnerability that has a lot to do with intrinsic features of individuals, but also that implies something about exposure and where they live. So, let's take a look from the perspective of climate change in health in cities and localities which is our focus in this course. Here's a conceptual model from a World bank guide to city vulnerability assessment. It shows risk of adverse outcomes in the middle and it's surrounded at the top, the red circle by hazards cities face from climate change such as heat waves or storms. Vulnerability, the topic of this lecture, is shown in the orange circle at the left, and in the case of a city, this has to do with its geographic features such as its topography and density of population. So, the maps that you see on the right are of Lagos, Nigeria, and these come from the same researchers that developed this model. These maps illustrate this: the upper map shows how much of the region of Lagos is just above sea level in red, the darker colors, and the lower map shows also in darker red, the areas of the city that are most densely built. So, we can see that the areas with the red shaded sections of these two maps overlap. In other words, the low lying and heavily populated areas of Lagos are going to be particularly vulnerable to storms and flooding. So, mapping factors we know lead to vulnerability in this way is among the most useful tools we have to plan adaptation actions. So, we have vulnerability reflecting not only intrinsic individual factors for populations, but also geographic factors of a city or locality itself. Then lastly, the blue circle on the right in the model shows adaptive capacity. Which is the flip side of vulnerability and includes for example, the resources, institutions, and other assets a city or individual may bring to bear on climate related challenges. So, we'll return to this idea of adaptive capacity later on and throughout the rest of the course. Here is a more recent model addressing some of the same concepts from a recent IPCC report, and this model more explicitly adds in the dimension of exposure. You can see in that lower lobe of the model. The other thing this model does is make clear the role of what are called here socio-economic processes. The boxes on the right that are shown as influencing vulnerability and exposure, and socio-economic processes are things like institutions and governance structures, such as public health agencies and actions to improve nuts and bolts infrastructure services such as roads, and water, or hospitals. So, this model reflects more recent thinking that builds in experience from disaster risk responses into climate change adaptation. Using these models, we can group what we're calling vulnerability factors into three broad and commonly used categories, and this slide provides a list of some examples for each. So, first, we've talked about individual factors such as age, or pre-existing health status. We've also talked about geographic factors which often overlap with exposures and include things like proximity to sea level or being in the storm track for major hurricanes, and then third, we'll talk about socio-economic factors such as the condition of water supply networks or the availability of health services. In most cases, cities and people in them may incur health risks from climate hazards due to a combination of these vulnerability factors. We'll walk through an example of each of these categories of vulnerability factors to illustrate using recent events. The 2003 heatwave in France gives us a good starting point for individual vulnerability factors. So, this map showing temperature differences between the summer of 2001 and the summer of 2003, shows just how hot it got in France that's summer. Over nine consecutive days in August, the average temperature of many parts of France was 10 or 12 degrees Celsius warmer than average, and that's reflected in the dark areas. You can see. As a result over the course of several weeks, there were about 15,000 excess deaths from heat-related conditions, and the greatest risk was found to be among the elderly, those living in institutional facilities, those lacking mobility and with pre-existing health conditions. These are some of the intrinsic characteristics of those individuals which made them more vulnerable to harm from extreme heat. Additional risk factors found in this case we're living in a building with poor insulation, living on the top floor where most of the heat was, and living in buildings without air conditioning. These are factors that have more to do with the built environment. A further factor was delayed recognition in some cases of the signs and symptoms of health-related illness in the health care system. These factors show us that it's often a combination, not only of individual factors, but also socioeconomic and exposure factors that create vulnerability. That 2017 Atlantic hurricane season and increased occurrence of nuisance flooding along the East coast of the United States give us a good way of thinking about vulnerability factors related to exposure and geography. Hurricane Harvey hit the city of Houston in August 2017 as a category four hurricane, and was among the most destructive in the United States. There were over a 100 deaths and 300,000 households without electricity. Many homes damaged and some of which are evident in the aerial photo shown at the right. The map of the United States shown on the left with the bright orange and blue lines shows the actual tracks of Atlantic hurricanes over the past, with the most severe shown in orange and red. Houston is near where that bright red streak is in the southern portion of the United States on the Gulf Coast. So, a major reason Houston is vulnerable to storms is that it is located directly on the path of strong Atlantic hurricanes. But there are other factors that make it subject to harm. The city is flat and low lying, it's also extensively built and therefore was extremely vulnerable to flooding, again, as the photo shows. It also has clay soil with poor permeability and runoff. So, it was also vulnerable for socioeconomic reasons to do with its built environment. A second example is nuisance or what's known as sunny day flooding, which also illustrates geographic risk. Along the coast of the United States, daily tidal flooding, in other words, not associated with any particular storm is now five to 10 times higher than it was 50 years ago. The photo at the bottom of the slide shows tidal flooding cresting on abnormal non-stormy day in the port of Annapolis, which is not far from Baltimore, Maryland in the United States. Nearly 40 percent of the US population lives along the low-lying East Coast alone, where such sunny day flooding is becoming more common. Being in the Atlantic storm track, as you can see on the map, further increases the risk of even worse surge-related flooding windstorms do occur. One such East Coast storm, hurricane Sandy and its impact on New York City, helps us to better understand some of what we've called socio-economic vulnerability factors or how institutions infrastructure and other elements of the built environment can affect health and an extreme weather event. Hurricane Sandy caused over 50 fatalities in New York due to drowning, trees falling, downed electric lines, along with injuries and other harms. It also caused losses and emotional mental stress for hundreds of thousands of people. However, many of the impacts occurred after the storm and were due to loss of services and facilities that people depended on. The photo shows tunnels to Manhattan were flooded. The subway system was flooded. Power supply was lost for several days in much of the city, and the impact on the health care system of loss of these infrastructure services was severe. Several hospitals were low-lying and were flooded or had power supplies that were vulnerable to flooding, and had to be evacuated, or had to operate under dire conditions. All of these in the context of an increase in demand for emergency services. Pharmacies were closed due to power outages and structural damage. Home-based healthcare was interrupted due to transport problems. The storm has since then led to a major effort to make New York City more resilient to the impacts of such extreme weather, including safeguarding its health care system and the core infrastructure services on which it depends. New York City's actions to build greater resilience address this opposite side of vulnerability, that is building adaptive capacity. So, returning to one of the diagrams we started with, we'll now pick up again on this idea of adaptive capacity. The definition here is from the IPCC extreme events report, and it's defined as a combination of strengths, attributes, and resources available to an individual or community that can be used to achieve goals. I'd like to also highlight here resilience which is a slightly different but related concept. I've given you the definition of resilience as well, this time from the United Nations Environment Program. Resilience has to do with an individual or community's ability to bounce back and recover from a shock. So, much of what we'll now talk about in the course has to do with how we can help address vulnerability and these three types of vulnerabilities we've talked about; individual, geographic, and socioeconomic by building adaptive capacity in individuals, in cities towards greater resilience, and in particular how city health departments and agencies can contribute to building that resilience. But before we wrap up on vulnerability, I'd like to take a step back and think with you globally about where we see some of the greatest vulnerability worldwide to a changing climate. This is a map based on an index produced annually by a group called Germanwatch, and this group's index is based on actual fatalities and economic losses from past extreme weather events. So, it only captures a part of what we're focused on when we think about vulnerability to health harms and building resilience in public health systems. But as you can see, many of the places most acutely vulnerable based on this index are in lower income countries around the world. Clearly, poverty is one major risk factor that makes populations vulnerable and reduces their adaptive capacity worldwide. This is a map from the World Bank showing global poverty based on the share of population living under a $90 per day as of 2013. The darkest shaded areas are those with the highest shares of poverty as measured in this way. In cities, in regions with greater poverty, will likely have populations with some of the greatest vulnerability, particularly in terms of socioeconomic factors, such as institutions and infrastructure. As an example, while Hurricane Harvey in the United States claimed over 100 lives, the massive flooding due to monsoon rains in India, Bangladesh, and Nepal that occurred in the same time period, led to 1,200 deaths and brought Mumbai one of the regions largest cities to a standstill, leaving a million children without classrooms. So, we started the lecture today with this man and his umbrella experiencing those floods, and he is a reminder also of the association of vulnerability and poverty. So, wrapping up the impacts of a changing climate on health will be felt differently by different populations depending on their vulnerabilities. We can see this as being individual intrinsic factors, geographic or exposure factors, and socioeconomic features having to do with institutions in the built environment. Usually, these factors interact together to enhance vulnerability. As we saw in the examples that changing climate that leads to extreme weather events, enhances existing vulnerabilities including urban poverty. Finally, identifying and reducing vulnerability will help build adaptive capacity and resilience, and we'll work together further to develop and illustrate these ideas as we continue the course.
