Hi. It's Mary Sheehan. Mary Fox. We're going to talk today about what impacts of changing climate has on population health. First, we'll give an overview of the health impacts of climate change, something that the WHO Director-General recently called the defining issue for public health In the 21st century. Then we'll go into some further detail on each of the different climate change risk areas and talk about why climate change is a challenge but also an opportunity for public health. So, Dr. Margaret Chan, the former Director-General of the World Health Organization, in several prominent addresses, called climate change the defining issue for public health in the 21st century. So, I'd like you to take a minute and think why she may have phrased it this way. What are some of the reasons she may have had? She went on to say that climate effects on health we're well-documented and visible and projected to increase substantially with time. But based on findings of the IPCC and other science experts, she noted the need for adaptation in public health systems. She also observed that health put people first and therefore could be an effective way of communicating about climate change. So, these two themes: the need for adaptation to climate effects in public health and the fact that public health can be an effective lens to look at climate change. These are two themes we're going to continually come back to in this course. So let's take a closer look. Climate change risks to health can be viewed like other risks to health in the context of hazards, vulnerability, and adaptive capacity. So that is, they happen because of a risk or hazard. For example, a heat wave, and the risk is that populations may suffer a heat stroke or heat stress. The impact will be felt more acutely by those who are most vulnerable. One example in the case of heat is elderly urban dwellers. Then their ability to manage or adapt to that risk will depend on how much adaptive capacity or resilience they have. In the case of heat in the elderly population, for example, do they have a park or green space? Do they have air conditioning? Take a moment now to look at the photos of some of these recent extreme events. On the left, you see severe flooding in India. What do you think were some of the main health risks? Who were likely to have been the most vulnerable to this hazard? What adaptive capacities might they have had or not had? What about in the case of Hurricane Maria on the right on the top that struck Puerto Rico and lead to wind and flooding damage, as well as major disruptions to road, electric power, and hospital services? What health effects were experienced? Who were the most vulnerable? What are their capacities to adapt? Or finally in the case of the devastating wildfires in Portugal or California shown in the photo, what were the health impacts? What were the vulnerabilities? What are the adaptive capacities? So let's take a step back and think about our definition of climate change. So climate change is a change in the mean or variability of climate properties. We know that key common properties are things like temperature, precipitation, and the patterns of oceans. Let's take a moment now and have you think about how changes in mean or variability of the key climate parameters are affecting you, where you are, your community. Do you know someone who has been affected by extreme temperature, extreme precipitations, extreme wind storms, or have you been affected? So let's take a look at what we already know about the main changes in the climate parameters and how they affect health. So, higher temperatures lead to things like heat exhaustion, more chronic kidney disease, increased cardiovascular disease, respiratory risks and many others, including drought and some of the indirect effects on things like our water supplies. More frequent, extreme weather events, be it precipitation, be it a hurricane, wind, things like risks of flooding, injuries and drowning. There's damage to homes and public infrastructure, mental stress and really devastating impacts like poor harvests, lack of food and water quality. So ocean changes, which include warming, acidification and then sea level rise complicate and exacerbate the extreme weather, the storms. There's lots of loss of life and threats to buildings, risks of the seafood supply, and things like having to relocate whole communities away from low-lying areas. In this figure, we are drawing from The Lancet, and this schematic helps us organize all of the information that we have about how climate change influences human health in direct ways, in indirect ways, and how our population and social dynamics also influence the health impacts that we feel now and going forward. The important thing that I like about this particular schematic, particularly if you look at the arrows that are on the top and the bottom, you can see that, very clearly, there are direct effects on human health of the particular drivers of weather and climate. These influence human health directly. There are the indirect effects of the climate changes on our ecosystems, our water, our air. These also influence human health. But the arrows on the top of the figure show us that all of these things in combination are also going to influence human health. To gain a bit more insight, we would encourage you to visit in course resources the short online animation that goes with this graphic from The Lancet, as well as an interview with Dr. Tony McMichael, one of the leading epidemiologists who has worked on climate change, regarding these direct and indirect effects. So, the table we have here on climate change hazards, health effects and vulnerable groups really gives you a very concise, helpful resource to organize all of the information that we've been talking about so far, all in one place. So, we have the categorized by direct, indirect, either biological, or ecologically mediated, and then the socially mediated indirect effects, specific examples of health effects, and some of the vulnerable groups. So let's look at the direct effect of air pollution, just for example to kind of walk through this table. So we know that increased air pollution is one of the climate hazards that we face. The type of health effects that we have known for many years about exposure to air pollutants are things like respiratory disease, cardiovascular disease, and allergies. The vulnerable groups here include the elderly, infants those that have some type of respiratory impairment, even athletes. So, a very broad group of vulnerable people to this particular hazard of the air pollution. So now here's a question. Will these effects be evenly felt across the globe? It's pretty clear that they will not be. These two maps are there to kind of show you that this is the case. So, for example, looking at Europe, you can see in this, this is the average annual difference in heat-related deaths per 100,000 people projected for the period 2071 to 2100. As you can see, the red is the highest level of deaths per 100,000 people, and the green is the lowest level. Southern Europe has much more red than Northern Europe. So, heat will have a much stronger impact in southern Europe than in northern Europe, at least according to projections. Similar when we look at the second map, which shows how much hotter the India, and Pakistan, and the south of Asia will be compared with the northern parts of China. Similarly, many coastal cities are at greater risk from sea level rise, extreme storms, and the accompanying storm surges. You can see this on the map on the left, showing economic losses from extreme weather, where large coastal cities of Asia and North America are particularly vulnerable. The second panel on the right shows the tracks and intensities of all tropical Storms, with red being a category five cyclone on the Saffir-Simpson hurricane intensity scale and indicating why those cities are likely to be at higher risk. So now, as we wrap up, we'll return to the World Health Organization perspective. Think about climate change is the defining issue for the 21st century for public health. Based on the strongest epidemiological evidence, projections indicate that between 2030 and 2050, climate change is expected to cause on the order of 250,000 deaths per year due to heat-related illness, diarrheal disease, malaria, and undernutrition. This doesn't count, of course, the deaths from air pollution around seven million deaths per year. There also due in large part to the same pollutants that lead to greenhouse gas emissions. Economic damages may be on the order of two to four billion per year by 2030. However, these impacts are likely to be low estimates. The Lancet recently reviewed the literature and concluded with a more sobering take that impacts on health of climate change are unequivocal and potentially irreversible. A couple of the remarkable features they flagged were the extremely large expected impact of heat on the elderly, a key vulnerable group as we've discussed in part because these age group is increasing with longer lifespans. They also flagged the rapidity of the spread of dengue fever, the large burden of air pollution and it's linked to climate change, as we've just mentioned, and the risks of child nutrition with drought. Their conclusion was that we have not done enough to protect lives and livelihoods but that there are major opportunities to act and public health. So, we will come back to this and focus on it, as we continue with the course. So, in summary, climate change is affecting us today in visible ways, and these health effects are likely to worsen substantially in coming decades. We have both direct and indirect effects of the changing climate on health. Direct effects including injuries and heat stress and indirect effects mediated through both ecological and social systems, such as increased vector-borne disease and mental health issues. The impact of the health outcomes on various people and populations will depend on their vulnerability and adaptive capacity. We've seen that the hazards and the health impacts are not evenly distributed around the world. Some regions are much more vulnerable to multiple hazards. Adaptation of public health systems to the changing climate is needed. Public health is a lens for considering climate impacts at the local level on all of us.
