We'll continue our conversation on climate change. In the last lecture, we made the case for anthropogenic or human induced changes to our planet. Now, we dive in on the impact to human health worldwide. Hello. We're going to continue the conversation of what I consider to be the greatest challenge to global health in the coming decades, climate change. This is part two when we'll consider how the climate changes discussed in part one affect human health. We'll go back to the 5th Assessment Report of the Intergovernmental Panel on Climate Change. Where it paints a grim prognosis. Until mid-century, predicted climate change will impact health mainly by exacerbating health problems that already exist. And throughout the 21st century, climate change is expected to lead to increases in ill health, especially in developing countries with low income. There'll be an increase in the frequency of extreme weather, particularly toward warmer temperatures. Some extreme events will be well beyond historical experience. The European heat wave of 2003 was one of the starkest examples of this. Here was a Northern European resource-rich metropolis that had little experience with temperatures over 40 degrees Celsius for a week straight. Apartments built in the 19th century had no central air conditioning. People did not know that they needed to check on their elderly neighbors, and public health officials did not know that shelters needed to be mobilized with access to water and air conditioning. 12,000 people perished alone, most in the banlieues of the lower socioeconomic strata. This is a theme I want you to understand regarding climate change and health. It's the most vulnerable. In this case, the poor and elderly who will bear the brunt of these changes. To be clear, climate change alone was not responsible for this heat wave. The message here is that we'll be seeing more of these extreme events with the same results and the most vulnerable people being at risk. He exacerbates physiologic vulnerabilities in other ways too. Quite simply, he acts as a stress to the human body. And for those of pre-existing illness, this added stress can have lethal consequences. A study out of the Harvard School of Public Health clarified that for each one degree Celsius increase in summer temperature, the death rate for elderly with chronic medical conditions increase between 2.8% to 4%. People with diabetes, heart disease and chronic lung disease are at much greater risk from extreme heat events. There are other things making this worse. Compounding the climate change driven increase in temperatures are the additive effects of the urban, built environment. Cities and climate are co-evolving in a manner that will amplify both the effect of heat as well as the vulnerability of urban populations to heat related death. For example, more than half the planet now lives in cities, up from 30% only 50 years ago. Urban areas are gaining an estimated 67 million people per year, about 1.3 million every week. By 2030, approximately 60% of the projected global population of 8.3 billion will live in cities. Additionally, there's a projected increase of 100 million more persons greater than 65 years old by the year 2100. This population increase will be accompanied by a rapid urbanization increasing a city's thermal storage capacity resulting in what's called an urban heat island effect. In real terms, relative to the surrounding rural areas, urban heat islands can add three and a half degrees Celsius to the urban heat load which has been linked with excess mortality. And studies have shown that lower socioeconomic and ethnic minority groups are more likely to live in warmer neighborhoods with less open park space and in an environment with not only greater exposure to heat stress, but with limited resources to cope with it. Heat, of course, is energy and the result of greenhouse gas accumulation is that we are adding more energy to the system. And that means more extreme weather in tropical cyclone intensity and storm surges. Last year, we saw the most powerful storm in recorded history as Typhoon Haiyan pummeled the citizens of the Philippines with maximum sustained winds of 196 miles per hour. We also saw the largest storm in recorded history strike the Northeast United States in the fall of 2012. Hurricane Sandy covered more than 1,000 miles of the North American coastline at its peak. Over 250 people lost their lives in this storm dupe with an estimate $65 billion in immediate damage. But there's a lesser known story here, one that speaks to vulnerable populations. This is a picture of Bellevue Hospital, the public hospital flagship of New York City, dedicated to treating the poor and underserved. In the USA, where there is no national health care system, this is the place where those who have little resources can go. It serves immigrants, the homeless, and those in the prison system. Bellevue has been a New York Institution since the 18th century. It's never closed and there are no locks on the doors. But after the storm surge from Hurricane Sandy caused a catastrophic power failure, the hospital closed for the better part of the year. That meant the hundreds of thousands of patients who sought care there now had no access to their medicines, emergency care, and no access to the very place that was designed for their well-being. New York is one of the wealthiest cities on the planet. It has the resources to build storm surge seawalls for the next extreme weather event. But even there in 2013, the most vulnerable lost their hospital from a climate related event. Heavy precipitation events can be expected to worsen and this means flooding. My parasitology professor in medical school spoke of the world's fecal veneer meaning that our planet is covered by varying layers of a microbiological film. Public health efforts throughout the world have focused on keeping this veneer thin where people live, and separate from the sewage and agricultural fields where it is thick. In essence, keeping us away from the germs that contaminate our foods and cause disease. Heavy precipitation events upend all of this. By overwhelming sewage systems, flooding farmlands, and causing landslides, which contaminate drinking water and spread infectious disease. When heavy precipitation combines with increased water temperatures, as well as agricultural nutrient runoff, algae blooms can literally occur overnight. Contaminating fisheries as well as exuding toxins that can poison human respiratory and nervous systems. Again, highlighting the extremes. Drier places will be drier, exacerbating drought and wildfires. Such dry conditions can cause health effects on other continents. Extreme conditions in Africa have been linked to increased asthma exacerbations and fungal infections in the Caribbean. But perhaps, one of the most worrisome effects of climate change is the changing ecosystems of vector born diseases like Malaria that are now spreading to higher elevations in more tempered regions. Places that have little experience and often little capacity to deal with these changing threats. In 2012, Madagascar had a surge in malaria. In East Africa, researchers documented a vast increase in mosquito habitats secondary to warming in the mountainous regions. Researchers were stunned to see malaria in Alaskan birds. Malaria outbreaks occurred in Southern Europe, decades after its eradication. And for the first time in nearly a century, mosquitoes carried Dengue fever to Portugal. In the last lecture, we spoke of the challenge of science communication. This guy is our nemesis. He's a farmer in Greenland, and he's smiling at his bumper crop. They're growing things there that they've never seen in the history of human habitation. And as great as that is for the subarctic regions of the world, the tradeoff is not equal. To be clear, the agricultural gains in the northern latitudes will not make up for the losses in the biodiverse regions of the world. And again, think about vulnerability. Look at the places where there is a loss in productivity in most of the developing regions of the world. So we need to ask ourselves, just how adaptable are we to these changes? You can see here that most species of the world will not be able to keep up with the temperature shifts in the ecosystems of the world. So what about humans? We can look to our recent past. Even in a resource-rich nation as the United States, the suffering of the poor as seen in the aftermath of Hurricane Katrina is an unfortunate sign of what's to come with climate change. And we see that ten years later, the profound effect on the livelihoods of New Orleans. Where 800,000 left their homes and neighborhoods. The IPCC foresees much more of this to come. Much of this in the low lying island nations. Other predictions are less causal but equally as serious. Again, to refer to science communication and the important concept of threat multiplier, articulated to me by Professor Skip Burkel. Threat multiplier does not imply direct cause and effect. Which can be difficult to prove. But rather as the idea that a stressor such as climate change can make already bad things worse. Again, the IPCC, which incorporates the concept of threat multiplier, an increased risks of violent conflict, economic shocks, prolong existing, and new poverty traps. The truth is that these threat multipliers will play out very differently to those living in Dhaka, New York, or Shanghai. So, here's where we are. And here's where we're headed. A 25% increase. All citizens who will want jobs, homes, cars, and some would say have a right to those things. To quote the American constitution in there pursuit of happiness. But as the science becomes clear, we have the ability to change our risk assessment, and perhaps think about other rights. We highlighted the issue of climate justice in an open access journal from the Harvard School of Public Health. Where Mary Robinson, the former President of Ireland and former United Nations High Commissioner for Human Rights, summarized the message. The vulnerable, marginalized and poor are disproportionately affected by extreme weather events, such as floods, storms and droughts. And slow onset events, such as sea level rise and glacial melt. Climate change is already undermining many of their basic human rights, to food, water, shelter and health. So where do we go from here? To start, we change our risk assessment by getting away from altruistic please to save our fellow species as well as abstract notions such as parts per millions of carbon dioxide. And instead, refocus the message to one of your loss of livelihood from a climate disaster, your parents premature death from an extreme heat wave, or your children's risk of increased asthma. Essentially, re-framing our understanding of what's at stake, and to understand that our choices today may have short-term gains, with long-term consequences to the human race. I'll finish with a story. In the early 1980s, a scary doctrine emerged within the Cold War. That nuclear wars were winnable. This was a frightening escalation from the mutually assured deterrents of previous decades. It was then that doctors and healthcare advocates from both sides of the iron curtain came together and declared that nuclear war would be the final epidemic with no meaningful cure. And because they form the international physicians for the prevention of nuclear war, in the name of human health and well-being, they were unimpeachable and were a powerful force in undermining the logic of nuclear proliferation. And they won the Nobel Peace Prize for it. We're facing a similar complex challenge to our well-being. By framing climate change as a health issue, we may have a fulcrum to alter the way people view risks in a tangible manner, and in turn, empower a personal and collective action in the name of global health.
