What do I mean by that? Often, it seems the messaging around the urgency to act on climate change gets lost in photos of forlorn-looking polar bears drifting on chunks of ice. Save the polar bears!!! The ice is melting and the polar bears will die. And, certainly polar bears are vulnerable to climate change (see this WWF Polar Bears and Climate Change Assessment [3]). But, my point is that we've been focusing on the wrong messaging about why we should care about climate change. While I don't like the idea of polar bears, or any species, experiencing negative impacts of a changing climate, I might not be inspired to act save polar bears because they feel kind of distant to me. Quite simply, we never should have made polar bears the unofficial mascots of climate action when ultimately, solving the climate crisis is something we need to do for our own well-being as a species.
If there's one thing we can say about humans, it's that we're inherently selfish (it's an evolutionary necessity in some ways). If we focus our climate change messaging on impacts that we feel much, much closer to home, we might just be able to inspire action. (And here, 'action' denotes not only action to address the causes of climate change but also action to respond to these possibly dangerous impacts.) So, for this week, we'll set our affinity for the fluffy white polar bears aside and worry about what climate change is already doing to people.
By the end of this lesson, you should be able to:
This lesson will take us one week to complete. Please refer to the corresponding module in Canvas for specific assignments, deliverables, and due dates.
If you have questions, please feel free to post them to the "Have a question about the lesson?" discussion forum in Canvas. While you are there, feel free to post your own responses if you, too, are able to help a classmate.
One of the biggest concerns that people have about climate change is how it might affect human health. What are the current and projected future health impacts of climate change? Who is at risk? What can be done to reduce those impacts and risks?
Climate change affects human health in three ways:
These effects of climate change do not act in isolation, however; environmental, social, and health system factors modify these impacts substantially.
This chart from the IPCC (it's an oldie but goodie from 2007) demonstrates the varying levels of confidence of several impacts on human health. We see red arrows of varying length pointing toward the left to denote negative impacts while we see blue arrows of varying lengths pointing to the right to denote positive impacts. What do you notice, though, about the size and frequency of the negative impact arrows vs. the positive impact arrows? (That's right! The negative impacts far outweigh the positive ones.)
Direct impacts of climate on human health occur when the human body is physically stressed or injured immediately by some element of the climate system.
Examples of direct impacts include:
Remembering that we're looking at the direct impacts on human health right now, we're thinking about the immediate impact events such as hurricanes, wildfires, droughts, and floods have on people's health. But how many people are affected by these various extreme weather events?
In 2015, the Centre for Research on the Epidemiology of Disasters (CRED) and the UN's Office for Disaster Risk Reduction (UNISDR) published The Human Cost of Weather Related Disasters 1995-2015 [5]. The timing of this report wasn't accidental - it was intended to help inform the urgency of the then-upcoming Paris climate negotiations producing meaningful targets for GHG mitigation. The two infographics below show the numbers of people affected and killed by weather-related disasters in 1995-2015.
The US Global Program on Climate Change [7] defines a heat wave as, "a period of two or more consecutive days where the daily minimum apparent temperature (actual temperature adjusted for humidity) in a particular city exceeds the 85th percentile of historical July and August temperatures for that city". Heat waves have been more frequent and more intense in the last few decades. As the maps and graphs below illustrate, not only are heat waves getting more frequent, the seasons in which they occur are getting longer.
But maybe when you look at these maps you think, "Ok, we're having more heat waves - that might be uncomfortable, but it's not actually affecting my health? Let's take a closer look. Remember in Lesson 3 when we were looking at vulnerability to climate change impacts and we talked about the 2003 heat wave in Europe and the almost 15,000 people in Paris who died (not to mention the 55,000 other people who died across Europe in that heat wave )?
Vulnerability plays a huge role in determining how a person or group of people experience climate change impacts. And yes, for many Americans, more heat waves are nothing more than an inconvenience. Perhaps I don't have air conditioning and will be uncomfortable. But maybe I have the resources (adaptive capacity) to minimize my exposure by staying with a family member with air conditioning, buying some fans, or spending the hottest parts of the day outside my home. My exposure might be similar to someone else's but as a healthy adult with reasonable resources, my sensitivity is lower and my adaptive capacity higher, thereby making me less vulnerable. While we saw that many of those deaths in Paris were elderly women, it's not just who you are that can make you vulnerable, but also what you do for a living. People who work outdoors have an obviously higher exposure to heat wave events and are therefore also more vulnerable to the direct health impacts those events bring (Xiang et al., 2014 [8]).
Let's take a look at a project in the Bronx to help identify residents most vulnerable to heat waves and the adaptation measures they're implementing to keep folks safe during extreme heat events.
As heat wave frequency and intensity increase in a changing climate, heat wave mortality also rises. This map (a) and graph (b) from that 2003 European heat wave shows the increased mortality across France that summer (this is calculated based on the mortality you'd expect under normal conditions) as well as the mean daily temperature in 2003 and its corresponding daily mortality compared to those values for the 1999-2002 time period.
NOAA's Billion-Dollar Weather and Climate Disaster Database [9] (yep, that's really a thing) includes four drought/heat wave incidents since 1980 in its list of deadliest events. It is interesting to note that heat wave mortality varies with location: in Russia, South Asia, and Southeast Asia, deaths were primarily in rural areas; in the US, deaths were almost exclusively in urban areas; and in southern Europe, deaths were in both rural and urban areas.
Wait. We just spent all that time talking about all of these more frequently occurring and more severe heat waves. Extreme cold? Although very cold days, very cold nights, and total frost days have declined over the past few decades, cold waves are still a problem and more recent studies are exploring the link between a changing climate and periods of extreme cold weather. This issue got a fair bit of attention in the early winter months of 2019, as the eastern US found itself subject to another polar vortex event. Cold weather is often a favorite talking point for overly simplistic climate denial, but in reality, the connection is much more complex and cold weather is anything but an indication that climate change isn't real. A changing climate is destabilizing the jet stream and allowing Arctic weather to dip down to lower latitudes than it otherwise would here in the US. Luckily, many popular news outlets tried to get in front of this by offering explanations of how climate change and cold snaps are related (see National Geographic's Why Cold Weather Doesn't Mean Climate Change is Fake [10], Climate Reality Project's Yes It's Cold, and Yes Our Climate is (Still) Changing [11], or Scientific American's Why Global Warming Can Mean Harsher Winter Weather [12]).
Much like heat waves, vulnerability is determined in a large extent to one's exposure. The most vulnerable among us are those people without adequate housing or reliable heat sources. People with existing health conditions or who are very young or very old are more sensitive. This NY Times article, Extreme Cold Weather Spreads East [13], offers a glimpse at many of the human health issues authorities were dealing with during this cold wave event in early 2019.
We'll be looking at extreme weather events in more detail in Impacts on Earth: Climate and Weather [15], but let's talk a bit about the specific human health dimensions of extreme weather. Obviously, heat waves and cold waves are forms of extreme weather too, but we tend to break those out separately from storms, floods, and droughts (though we can certainly group droughts and heat waves together). This is a recurring theme with the topics we're discussing this semester - they're all inextricably linked, and there's never a good starting point or logical progression.
Indirect impacts of climate on human health are ones in which the human body is not immediately affected by the climate system but instead feels the delayed impacts through some intermediary. Indirect impacts affect many more people in many more ways than the direct impacts. The list is long and includes, among others:
Several food-borne pathogens are spreading due to climate change. Depending on the crop type, drought and excess moisture encourage crop pests and spread molds. Climate-driven rusts, blights, and rots are devastating already stressed crops and thereby indirectly affecting human health through decreased food security.
But it's not just our crops falling ill from increased pathogens in a changing climate. Instances of some types of pathogens that make their way to people are also on the rise. The US Global Change Research Program's Climate and Health Assessment from 2016 describes some of these pathways and consequences (and in their bulleted list [17], they include ample citations to support each bullet point - I'm linking out to that directly in hopes the links there are updated as necessary):
Water-borne diseases are closely related to weather and climate. Cholera, cryptosporidiosis, and several other significant diseases are spread by fecal contamination of water supplies and are often closely associated with floods and heavy downpours. In other cases, drought can concentrate disease pathogens in pools and low flows. Climate change is causing increased intense rainfall events in many parts of the world and drought in others; it is not surprising that water-borne illness is a growing problem in those areas with the most extreme changes. The key to understanding the spread of water-borne illness in a changing climate is exposure. As this image shows, various factors (all from human activity) are increasing our exposure to these illnesses.
Disease vectors, such as mosquitos and ticks, are moving into new areas as warmer, wetter climates push poleward and upslope. The spread of malaria and dengue fever, for instance, is believed to be at least partly due to mosquitos expanding their range with the changing climate.
Click through this series of maps illustrating the projected expansion of mosquitos carrying Aedes-borne viruses (dengue fever* and Zika among them). These projections are based on an RCP (representative concentration pathway [20]) of 8.5 which is really a worst-case scenario in which we continue on with our business as usual practices and fail to mitigate climate change. So, with any luck, this won't happen! But, you can also see a set of projections based on a more plausible RCP with the original paper (Ryan et al., 2019 [21]). These projections demonstrate the rapid increase in exposure for highly populated areas, some expansion into new areas - meaning newly vulnerable populations.
*In 2019, countries across tropical Asia saw higher than usual instances of dengue fever.
Let's take a look at another vector, ticks. Look at the massive growth in reported cases of Lyme Disease [25] between 1996 and 2014. Many of you live in Pennsylvania or surrounding states, so you're likely all too familiar with ticks and Lyme Disease. Most of us have a story or two of pulling a deer tick off ourselves, our children, or our pet. I've spared you a close-up image of a deer tick on this page, you're welcome.
Rodents and their fleas are also a concerning disease vector with changing distributions in a changing climate. For example, Hantavirus borne by fleas on deer mice is closely linked to the ENSO cycle in the US Southwest (Hjelle and Glass, 2000 [27]), and evidence points to climate-related distribution changes in Europe of Hantavirus borne by other rodents (European Center for Disease Prevention and Control, n.d. [28]). In Brazil, warmer temperatures mean an increased expansion of sugarcane production. Rodents (particularly deer mice) find sugarcane quite tasty and estimates suggest that this combination of increased sugarcane production and warming temperatures could expose an additional 20% of Brazilians [29] to this potentially fatal virus.
Sometimes, when I'm having a conversation about climate change (as one does!), I hear people talk about our greenhouse gas emissions as pollutants. I've personally never really thought of them that way (even though, perhaps I should because they do overlap), because I tend to think of air pollution as particulate matter - soot, big puffs of black exhaust from the back of a truck, things like that. Greenhouse gas emissions seem categorically different to me - like secret pollutants we can't see. However, it's important to understand that regardless of how you conceive of GHGs and pollutants, our GHG emissions are affecting the more traditional air pollutants in ways it's important for us to understand.
Air quality and its effect on human health is in large part a function of the weather, which creates conditions that promote or depress the formation, concentration, deposition, dispersion, and transport of pollutants. Changing climate means changes in location, timing, and intensity of air pollution events. Ground-level ozone, the most noxious constituent of photochemical smog, is associated with a host of health problems and is strongly and positively correlated with temperature and solar radiation; increases in temperature and longer summer seasons correspond to increases in general ozone concentrations and the number of days violating air quality standards. Here's a short EPA podcast from 2016 called The Future of Breathing: Connecting Air Quality and Climate Change [30] I'd like you to spend 2 minutes on (or read its transcript).
Particulate matter (PM) has even greater health effects than ozone; this pollutant is also linked to temperature and humidity in its formation. Forest fires also release many particulate air pollutants and toxic gases and are known to affect health. Forest fires are on the increase worldwide and forecast to escalate dramatically in the future.
Let's circle back to thinking about vulnerability and how people might experience this type of impact of a changing climate differently than those around them. The American Lung Association [31] estimates 26 million people in the US are living with asthma. Poor air quality is just one potential indirect impact on human health that affects people with asthma more acutely.
One of the biggest climate impacts on human health is through seasonal allergens. Over the past few decades, spring is coming earlier and fall is ending later in the Northern Hemisphere, increasing the length of the allergy season. (Do you hear the collective groan of the roughly 30% of the population who suffer from seasonal allergies?) Changing distributions of plants and molds (thanks to extreme precipitation events and changing temperature patterns) are causing the spread of allergens into areas where they did not exist earlier. There is also some evidence that the rising atmospheric CO2 concentration is fertilizing some allergen-rich species, like ragweed (Albertine et al., 2014 [33]).
What do you notice about this map? The northern latitudes of the US and the western part of the country are seeing rapidly expanding numbers of frost-free days relative to the southern US. It's just another reminder that while impacts are global in nature, they materialize very differently across smaller geographic scales.
For this week's lesson, let's focus specifically on the effects climate change impacts can have on one's mental health. This is separate from thinking about the mental health implications associated with people worrying about climate change in general (which is a rapidly growing issue). We'll probably have a chance to tackle that in Unit 3: Solutions.
This area seems a bit understudied compared to the more obvious impacts and isn't discussed as much publicly. Flooding, droughts, Lyme Disease, asthma - we've talked about a lot of potential issues connected to climate change that might seem more connected. But, the mental health implications of living through many of these impacts is of serious consequence and worth our time to better understand.
Mental health is inextricably linked to physical and community health (see those bidirectional arrows between the physical, mental, and community symbols - it's all connected!).
It is important to recognize that climate change is neither the primary driver of human health today nor will it be in the future. Beyond genetics, access to these three factors are fundamental to the good health of an individual and a society.
In summary, individuals who live in developed countries generally have better access to safe water and sanitation, good nutrition, and health care. People who live in the least-developed nations often have unsafe water and poor sanitation, inadequate nutrition, and little access to health care. Therefore, with or without climate change, health outcomes vary based on a person's country of residence and its level of development.
With a growing global population that's becoming increasingly urban and aspiring to middle class lifestyles, the demands on our food, water, and energy systems is expected to grow considerably in coming decades. Add climate change into the mix, and this creates a very precarious nexus of demands for basic needs like food and water.
Food insecurity linked to climate change impacts will be one of the most pressing consequences of a changing climate. Many areas of the globe –– particularly in Africa –– lack basic food security. Droughts and floods aggravate already bad situations, reducing yields and sometimes causing crop failure, further weakening already vulnerable populations.
This week, we'll explore just a few examples of the impacts of climate change on our global food security, recognizing that the impacts are complex, intertwined, and far-reaching. These examples include:
Sometimes, climate change impacts create winners and losers. It's important to understand that climate change leading to food insecurity is more nuanced than it's hotter here and we can't grow food. Climate shifts happen regionally and it's important to understand what that looks like at a smaller scale. Take a look at this map of anticipated agricultural yields in the US by the end of the 21st century. What do you notice?
The issue is more complicated than deciding to follow the climatic conditions with our farming. What does this mean for land use planning, both in the places which stand to lose productivity and those which stand to gain?
In a changing climate with predominant warming trends, we're seeing the lengthening of our growing seasons (as defined by the period of time with frost-free days). Given what we understand about the increased pressures to feed a growing global population, a longer growing season sounds like it might be the silver lining of climate change impacts we've been searching for, doesn't it? Let's take a closer look.
A longer growing season does mean that some crops and forests are growing for longer periods of time each year; sequestering more carbon dioxide from the atmosphere - good news! But, longer growing seasons for good plants also mean longer growing seasons for less desirable plants. Remember when we looked at the lengthening of seasonal allergy seasons when we talked about human health? Plants like ragweed will enjoy these longer growing seasons, too (EPA, 2016 [59]).
Climate change is creating major consequences for water resources through its impacts on the planet’s hydrology.
To put it another way, our impacts on water are a bit of a double whammy. Because anthropogenic climate change is altering water’s distribution, movement, and quality, climate change is also causing humans to adjust the ways we use water.
We'll spend a fair bit of time exploring the impacts of climate change on water resources and understanding how these impacts vary from place to place. But first, it takes a look at the physical impacts of climate change on hydrology so we approach that exploration with a solid foundation of its root causes.
Alterations in hydrology caused by climate change are complex. A simple increase in average temperature results in greater evaporation from soils, drying them out and providing less water to plants and diminished input to groundwater. Less soil water and groundwater lead to lower stream and lake levels and reduced wetland areas. Increased temperatures also mean greater evaporation from lakes and wetlands. Greater evaporation from land surfaces and water bodies, including the oceans, produces more water vapor, which translates into global precipitation increases. (Oh, good news! A few sentences ago it was looking like we were having less water enter the groundwater. Not so fast...)
Those increases, however, are not evenly distributed in time and space (geography matters!). Those places getting much more precipitation find that the increased precipitation offsets the greater evaporation from land and water surfaces; these places are wetter. Those places seeing only a modest increase in precipitation or no increase at all find that increased evaporation rates overshadow precipitation and total available water decreases. Finally, in combination with increased evaporation, those places receiving less precipitation are much drier than before climate change.
These combinations of factors become even more complex if the seasonality of precipitation changes. Some places are becoming wetter in some seasons and drier in others, and the impact of those changes on hydrology is a function of which season is becoming wetter and which one is becoming drier, of the timing of those changes in the annual water cycle, and of the type of precipitation that falls. For example, some mountainous regions are finding that the first snowfall in autumn is coming later and the last snowfall in spring is coming earlier. This change means that the snowfall season is much shorter and snowpacks are much thinner on average. Not only does that change result in less water in the snowpack, but also it causes the release of that water with spring melt to come earlier and to have a significantly smaller peak flow in streams. Regions that rely on mountain snowpacks for their water supply watch these changes with growing alarm. This feels a bit confusing; let's walk through this more carefully with The Importance of Mountain Snowpack to Water Resources [63]. I like this brief write-up because it talks about a few specific regions in the US and what this means for each of them.
More water vapor in the atmosphere from increased evaporation causes some areas to get more rainfall. When the greater latent heat stored in the evaporation process is released by condensation–that is, the formation of clouds–this energy produces stronger updrafts with more liquid water and, ultimately, heavier precipitation. Indeed, like most other areas on Earth, observed precipitation over the United States shows that precipitation totals have been going up for the last century. Moreover, precipitation events are getting more intense and these stronger events are becoming more numerous over most of the country.
The payoff from these changes in hydrology is easy to understand and to document. Despite overall increases in precipitation, drought is becoming more frequent because in those areas where precipitation has not been increasing strongly, greater evaporation results in drier soils and less available water. Even in areas that are becoming wetter on average, a period of decreased rainfall––say, a few weeks––coupled with higher temperatures results in quick drying and rapid conversion to drought. Ironically, the more frequent, more intense downpours lead to more flash floods. Prolonged, stronger wet periods also generate more floods. Thus, climate change results in greater hydrologic variability over time and space, producing more droughts and floods overall and in any one place. Streamflow and groundwater is, therefore, more variable than ever and much harder to predict and manage.
It is worth noting that sea-level rise resulting from climate change also affects hydrology. Saltwater intrusion into coastal aquifers is increasing partly from greater extraction by growing human populations, and partly from the greater osmotic pressures produced by rising sea levels. Simply, when people install wells, they draw down the water table, causing pressure that can pull saltwater into the aquifer. Concurrently, as sea levels rise, the pressure of all that water can force saltwater into the groundwater system. Saltwater is also increasingly working its way upstream in estuaries and coastal rivers, degrading and replacing freshwater.
The impacts presented above are an important subset of the total changes to hydrology produced by climate change. The following section explores how these hydrologic impacts translate into challenges for water resource and other managers.
Drought is especially tough on agricultural production. Nearly all crops require moisture as they germinate, grow, mature, flower, and fruit. Yields of water-intensive crops especially depend on how much water is available during crucial life stages. For instance, corn yields are strongly associated with temperatures and precipitation totals in July: if conditions are cool and wet in that month, then yields will be high; if it is dry and hot in July, then yields will be low. Livestock operations also depend on water. For example, because feedlot cattle require significant quantities of water per cow per day, when drought strikes, feedlots must cut back on the number of cattle they process. It is easy to see that those areas experiencing increased frequencies and intensities of drought because of climate change will feel substantial impacts on agriculture output.
Drought influences many aspects of society beyond municipalities and agriculture. For instance, drought even has a big impact on transportation. A large proportion of U.S. commercial transport occurs on barges along the Ohio, Missouri, and Mississippi Rivers and their tributaries. Over 40 percent of all US grain exports travels on the Mississippi River alone. The devastating drought of 1988 stopped all barge traffic on the Mississippi for weeks and affected billions of dollars in exports. The less severe, but prolonged drought affecting the Missouri River drainage from 2003-2010 diverted products totaling many billions of dollars away from barges and onto less cost-effective trains and trucks. If climate change were to cause more droughts in the Midwest or generally dry out the area, then transportation costs and, subsequently, food costs would rise.
Wet and dry periods have major impacts on the water quantity and water quality of both surface water and groundwater systems. Water quantities go up during wet spells and down during dry spells. Dams and reservoirs help solve surface water quantity problems by helping to control floods during wet periods, holding back floodwaters and allowing them to release gradually, thereby reducing the impact of the flood wave generated by nature. At the same time, dams and reservoirs help maintain adequate water supplies during dry periods by impounding water -- perhaps generated during earlier wet periods -- and releasing it as needed. Climate change could therefore necessitate more dams and reservoirs, with the large economic and environmental costs associated with them, such as the impacts on communities submerged by reservoirs or the impacts on ecosystems caused by changes in the quantities and timings of streamflows.
Groundwater quantities are also greatly influenced by wet and dry periods, with water tables rising when climate is wetter and falling when climate dries. One effect of rising and falling water tables is rising and falling streams. Many people do not realize that most water in streams comes not from storm water, but instead from groundwater. Streams occur at low points where the land surface intersects the water table, so when groundwater rises, stream levels rise. Conversely, when the water table falls below the streambed, the stream dries up, running only when a storm temporarily washes water into the channel. Climate change impacts on groundwater therefore will result in changing streams. Another, more purely human, technology associated with groundwater levels is wells. Wells experience few problems when water tables are high, but when they fall it becomes more difficult for wells to pump water, requiring well owners to purchase bigger pumps or -- in those cases when the water table falls below the well depth--dig deeper wells. Deeper wells and stronger pumps result in overpumping and a further drawdown in the regional water table. Consequently, those areas dependent on groundwater where climate change lowers the water table should expect less and more expensive water.
Water quantity is not the only aspect of water resources affected by climate; climate change will also affect water quality. Where net water quantities increase by moderate amounts, surface water quality will generally improve as streams and lakes fill and dilute their pollutants; where available surface water decreases, pollutants will concentrate and water quality will go down. In those areas where water quantities go up dramatically, or where intense precipitation events become more common, water quality will deteriorate substantially as more pollutants are washed into water supplies. Moreover, overloaded storm and sewage systems will spill effluent into streams and water supplies, producing important health hazards. Exceeded capacities will lead to damages, not only causing health hazards but also costing taxpayers large sums to repair, modify, or replace inadequate and damaged systems. Groundwater quality is declining, too, with climate change. Increasing heavy downpours are washing pollutants into wells more frequently, compromising local drinking water supplies after each heavy precipitation event. Sea level rise is causing more frequent cases of saltwater intrusion into groundwater supplies, making coastal drinking water unpleasant in many instances and undrinkable in others.
Climate change is also increasing competition for water resources. Competition for water already exists in drier areas. The U.S. and Mexico compete over Colorado River water, and Northern and Southern California compete for meltwater from the Sierra Nevada Mountains, for example. Such rivalries will increase as climate continues to dry in the Southwest, snowpacks continue to shrink in California, and other regions experience decreases in water resources. There will be competition not only within regions, but also between regions as water-poor regions fight for survival and water-rich regions seek to maintain competitive economic advantage.
In addition, climate change is bringing growing competition between and within market sectors. For example, in many regions of the nation, competition already exists as agricultural interests, municipalities, and energy production companies vie for shrinking water resources; that struggle is growing more combative over time, even resulting in calls for changes in longstanding water laws. Within sectors, such as agriculture, economically and politically entrenched water-intense activities are competing for water with less powerful, more environmentally sensitive, and less water-intense practices. Such competition will continue to intensify as the distribution of water over time and space changes with the climate.
North America is not the only continent facing this problem. The Murray River in Australia, for instance, is drying up and not reaching the population centers near its mouth. The cause of this drying is a combination of long-term drought and overuse by upstream farmers growing such water-intensive crops as rice. Severe competition therefore exists between agricultural and urban interests.
This week, we've been looking at some of the ways climate change impacts people in very up close and personal ways: our health, our food supply, and our water supply. We learned that climate change is having significant impacts on human health today; it will have even more dramatic impacts on health in the future. Those impacts either are direct, such as heatstroke, or indirect, such as disease transmission through mosquito vectors. One of the key takeaways, as we think about the effects on our health, is that they are varied, pervasive, and expected to become more severe as climate change impacts become even more acute.
We've also looked at impacts on water and food. It doesn't get more integral to our survival than this (remember - not [just] about polar bears).
The story of food security and climate change is one of geography and compounding vulnerabilities. The shifts in where we can grow certain types of food is inherently a geographic problem to understand and carries economic, environmental, and social consequences of great import. Water poses more risks for competition-related issues. Both exacerbate vulnerable populations that may be experiencing insecurity for these basic necessities even before the impacts of climate change really take hold.
"When the well is dry, we know the worth of water." (Benjamin Franklin, Poor Richard’s Almanac, 1746.) Many of you seemed to come to a similar sentiment in your Write to Learn assignments that asked you to talk about what aspects of climate change impacts on human health you were most concerned about or how you personally felt most vulnerable to climate change, and as I told some of you, nothing else really matters if we don't have water. (Ben Franklin and I are clearly on the same page, except about kites and thunderstorms.)
Climate change is profoundly changing Earth’s hydrology, giving us too much water in some places, but too little water in others; giving us too much water at one time, but not enough water over time, and giving us rain, but not snow. (Instead of the line from The Rime of the Ancient Mariner water, water, everywhere but not a drop to drink (a sailor surrounding by salty seawater he cannot drink) it's more like water, water - not there, not like that, not then!!!) Perhaps the greatest challenge posed by climate change is deciding how to adjust our water resource use to address the new normals of hydrology.
Decision-making takes place at all scales of human endeavor, from individual and household levels to community, state, national, and international levels. People regularly make decisions about water use at all these scales, including decisions that have time horizons of decades to centuries. Humanity, therefore, appears to be equipped to handle the water resource challenge presented by climate change. Although competing economic, political, cultural, and social interests will undoubtedly make this task more difficult than it needs to be, humans are infinitely resourceful and will figure out how to meet this challenge and, in many cases, turn it to their advantage.
You have reached the end of Lesson 6! Double-check the lesson assignments in the corresponding lesson module in Canvas to make sure you have completed all of the tasks listed there.
Links
[1] https://pixabay.com/users/358611-358611/
[2] https://pixabay.com/service/license/
[3] https://www.worldwildlife.org/pages/polar-bears-and-climate-change
[4] https://www.ipcc.ch/report/ar4/wg2/human-health/
[5] https://www.preventionweb.net/files/46796_cop21weatherdisastersreport2015.pdf
[6] https://www.undrr.org/publication/human-cost-weather-related-disasters-1995-2015
[7] https://www.globalchange.gov/browse/indicators/us-heat-waves
[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4202759/
[9] https://www.ncdc.noaa.gov/billions/events
[10] https://www.nationalgeographic.com/environment/2019/01/climate-change-colder-winters-global-warming-polar-vortex/
[11] https://www.climaterealityproject.org/blog/yes-cold-yes-our-climate-still-changing
[12] https://www.scientificamerican.com/article/earthtalks-global-warming-harsher-winter/
[13] https://www.nytimes.com/2019/01/31/us/weather-polar-vortex.html
[14] https://www.noaa.gov/multimedia/infographic/science-behind-polar-vortex-you-might-want-to-put-on-sweater
[15] https://www.e-education.psu.edu/geog438w/node/614
[16] http://www.fao.org/tempref/docrep/fao/011/i0378e/i0378e.pdf
[17] https://health2016.globalchange.gov/food-safety-nutrition-and-distribution#table-125
[18] http://climateandhealthalliance.org/uncategorized/climate-change-and-food-safety/
[19] https://health2016.globalchange.gov/water-related-illness
[20] https://www.ipcc-data.org/guidelines/pages/glossary/glossary_r.html
[21] https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0007213
[22] https://www.npr.org/2019/07/31/747012629/bangladesh-reports-more-than-13-000-dengue-cases-in-july?fbclid=IwAR0NQWLtp3v2EGO_8zHF2ySpBF1-5MHk6DUqZ0XU7WWWN7tXAhoSRXSwp7c
[23] https://www.straitstimes.com/asia/se-asia/philippines-declares-national-alert-after-456-dengue-deaths
[24] http://outbreaknewstoday.com/peak-dengue-season-in-singapore-8000-cases-5x-last-years-number-26932/
[25] https://www.cdc.gov/lyme/index.html
[26] https://www.cdc.gov/lyme/datasurveillance/index.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Flyme%2Fstats%2Findex.html
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