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Climate Change and Its Impact on Pandemics

Grades 9-10 | Informative | Source-Based

Source Lexile®: 1140L-1360L

Learning Standards




Prompt: The causes and effects of climate change continue to grow, and, in turn, affect more and more people across the globe. One effect of climate change that is not widely focused on is the increased risk of the spread of disease throughout the world, also known as pandemics. Read the following articles about climate change and pandemics. Then write an informative essay which explains the relationship between the two. Be sure to include evidence from the text to support your essay.



Source 1

What Is a Pandemic?


A pandemic is the worldwide spread of a new disease.


An influenza pandemic occurs when a new influenza virus emerges and spreads around the world, and most people do not have immunity. Viruses that have caused past pandemics typically originated from animal influenza viruses.


Some aspects of influenza pandemics can appear similar to seasonal influenza while other characteristics may be quite different. For example, both seasonal and pandemic influenza can cause infections in all age groups, and most cases will result in self-limited illness in which the person recovers fully without treatment. However, typical seasonal influenza causes most of its deaths among the elderly while other severe cases occur most commonly in people with a variety of medical conditions.


By contrast, this H1N1 pandemic caused most of its severe or fatal disease in younger people, both those with chronic conditions as well as healthy persons, and caused many more cases of viral pneumonia than is normally seen with seasonal influenza.


For both seasonal and pandemic influenza, the total number of people who get severely ill can vary. However, the impact or severity tends to be higher in pandemics in part because of the much larger number of people in the population who lack pre-existing immunity to the new virus. When a large portion of the population is infected, even if the proportion of those infected that go on to develop severe disease is small, the total number of severe cases can be quite large.


For both seasonal and pandemic influenza, the highest levels of activity would be expected to occur in the usual influenza season period for an area. (In the temperate climate zones, this is usually the winter months, for example). But as was seen with the current H1N1 pandemic, pandemics can have unusual epidemiological patterns and large outbreaks can occur in the summer months.




Source 2

Could Climate Change Cause The Next Cholera Pandemic?

New research suggests we may be closer to a global cholera outbreak than once believed

By Jason Tetro

June 18, 2015



Throughout history, only a few pathogens have made historical impacts on human health. One of these is cholera. Caused by the bacterium Vibrio cholerae this potentially fatal disease has caused more pandemics than influenza, plague and smallpox. The most recent, the seventh, occurred in the 1960s when many parts of Asia suffered for four agonizing years.


Today, cholera has been for the most part controlled and limited to only a few places such as Bangladesh and Haiti. These countries appear to have seasonal intervals of infection and are continuing to be monitored. Yet, since the early 1990s, the concern for another pandemic has been haunting public health officials. What makes their worry more pressing is the fact the oncoming onslaught may be due to a factor seemingly out of our control: climate change.


Changes in climate are not limited to levels of atmospheric carbon dioxide or recorded temperatures. Though these are the factors gaining the most headlines, other factors play a role in determining climatic shifts. One of the most important in terms of cholera is the interface between the atmosphere and the ecological niche of the oceans. Changes in ocean patterns can lead to dramatic shifts in weather such as the El Niño Southern Oscillation. Other changes also occur resulting in global variations of local climatic conditions. Skipping over the debate over what might be causing these shifts, the reality is they are occurring and can impact how and more importantly where pathogens live, thrive, and infect.


In the context of cholera, changes in climate are stressors on microbes forcing them to either die off or figure out means to adapt to the conditions. In Bangladesh, this has been shown through the evolution of the classical strain to one known as El Tor. This particular strain relies less on seasonality and occurs more frequently. The overall result is a year round threat of infection as opposed to only during the rainy season. As to the reason behind this variant, the cause appears to be related to less divergence between the rainy and dry seasons. This has allowed the El Tor strain to develop resistance to drier weather over time such that it can survive in any climatic environment.


But the emergence of a new strain does not a pandemic make. In order to cause global troubles the bacteria also have to spread out and become endemic in a variety of regions. To accomplish this, they need proper temperature and food sources, which too can be aided by climate change.


In 2011, several possible factors were examined to determine if one or a combination could lead to intensified growth and transmission of the bacterium. There were two specific factors implicated, none of which had to do with temperature. They included a higher level of discharge from rivers into the oceans and the level of phytoplankton. Interestingly, the temperature of the sea surface was not implicated as a factor. Although higher temperatures did coincide with more cholera outbreaks, this wasn't universal. Without discharge, there was little chance for an outbreak.


With this evidence in hand, the potential for drawing a map of at-risk areas could be developed. Last week, an international team of researchers who undertook the task revealed their results. They developed a global map where cholera may be able to live currently as well as into the future. Based on the findings, there is every reason to believe we are on the verge of another pandemic, and this time, even North America may see a return.


The team used 12 environmental variables obtained from an existing marine dataset called Bio-ORACLE. These included climate-associated factors such as sea surface temperature, sunlight, and levels of microbial growth. The others focused on physical attributes such as salinity, pH, dissolved oxygen, nitrate and phosphate levels. From there, they examined regions known to have cholera growth. From this analysis, they were able to define a list of parameters necessary to harbor, grow and spread the bacteria.


At this point, the team went looking at other areas around the world for similar environmental conditions. Using statistical analysis, they were able to determine suitability as a percentage. The most likely places had at least a 50% chance of allowing enough growth to cause an outbreak. They performed this for current climatic conditions and for the year 2100.


Although the authors expected to find more than a few places where cholera could survive, the data showed an almost-global distribution of environments prime for growth. These included expected areas such as Peru, Ecuador, West Africa and parts of Australia. But some regions were completely unexpected such as the North Sea, regions south of the Scandinavian countries. In the American context, the Gulf of Mexico and the entire East Coast of America would also be prime spots for cholera to grow.


As for the year 2100, the situation was dramatically worse thanks to climate change. Some of the most northern regions of the world, including the Pacific Northwest, Hudson's Bay in Canada, the west coast of Ireland, and the northern tip of Russia all could support cholera. The Southern hemisphere also would suffer, though not as much. Temperatures played a more significant role in this case but still required other climate-change-related factors to ensure survival.


The results of the study reveal we are already in a position for another cholera pandemic. The locations are just waiting for the bacterium to invade and conquer. Although the likelihood of this occurring is minimal, for public health officials, knowing these regions exist is at least an early-warning system. The information from this exercise also offers the ability to monitor climate change into the future to look for any suspect changes at the local level. If sudden shifts occur, public health officials can be given warning so they can increase surveillance and prioritize cholera-prevention awareness. Although this work may not stop the eighth cholera pandemic from happening, it can at least give us a fighting chance.




Source 3

The Consequences of Climate Change


Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted, and trees are flowering sooner.


Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise, and longer, more intense heat waves.


Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century.


According to the IPCC, the extent of climate change effects on individual regions will vary over time and with the ability of different societal and environmental systems to mitigate or adapt to change.


The IPCC predicts that increases in global mean temperature of less than 1.8 to 5.4 degrees Fahrenheit (1 to 3 degrees Celsius) above 1990 levels will produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over time as global temperatures increase.


"Taken as a whole," the IPCC states, "the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time." 1



Future effects


Some of the long-term effects of global climate change in the United States are as follows, according to the Third National Climate Assessment Report:

  • Change will continue through this century and beyond: Global climate is projected to continue to change over this century and beyond. The magnitude of climate change beyond the next few decades depends primarily on the amount of heat-trapping gases emitted globally, and how sensitive the Earth's climate is to those emissions.
  • Temperatures will continue to rise: Because human-induced warming is superimposed on a naturally varying climate, the temperature rise has not been, and will not be, uniform or smooth across the country or over time.
  • Frost-free season (and growing season) will lengthen: The length of the frost-free season (and the corresponding growing season) has been increasing nationally since the 1980s, with the largest increases occurring in the western United States, affecting ecosystems and agriculture. Across the United States, the growing season is projected to continue to lengthen. In a future in which heat-trapping gas emissions continue to grow, increases of a month or more in the lengths of the frost-free and growing seasons are projected across most of the U.S. by the end of the century, with slightly smaller increases in the northern Great Plains. The largest increases in the frost-free season (more than eight weeks) are projected for the western U.S., particularly in high elevation and coastal areas. The increases will be considerably smaller if heat-trapping gas emissions are reduced.
  • Changes in precipitation patterns: Average U.S. precipitation has increased since 1900, but some areas have had increases greater than the national average, and some areas have had decreases. More winter and spring precipitation is projected for the northern United States, and less for the Southwest, over this century. Projections of future climate over the U.S. suggest that the recent trend towards increased heavy precipitation events will continue. This trend is projected to occur even in regions where total precipitation is expected to decrease, such as the Southwest.
  • More droughts and heat waves: Droughts in the Southwest and heat waves (periods of abnormally hot weather lasting days to weeks) everywhere are projected to become more intense, and cold waves less intense everywhere. Summer temperatures are projected to continue rising, and a reduction of soil moisture, which exacerbates heat waves, is projected for much of the western and central U.S. in summer. By the end of this century, what have been once-in-20-year extreme heat days (one-day events) are projected to occur every two or three years over most of the nation.
  • Hurricanes will become stronger and more intense: The intensity, frequency and duration of North Atlantic hurricanes, as well as the frequency of the strongest (Category 4 and 5) hurricanes, have all increased since the early 1980s. The relative contributions of human and natural causes to these increases are still uncertain. Hurricane-associated storm intensity and rainfall rates are projected to increase as the climate continues to warm.
  • Sea level will rise 1-4 feet by 2100: Global sea level has risen by about 8 inches since reliable record keeping began in 1880. It is projected to rise another 1 to 4 feet by 2100. This is the result of added water from melting land ice and the expansion of seawater as it warms. In the next several decades, storm surges and high tides could combine with sea level rise and land subsidence to further increase flooding in many regions. Sea level rise will continue past 2100 because the oceans take a very long time to respond to warmer conditions at the Earth's surface. Ocean waters will therefore continue to warm and sea level will continue to rise for many centuries at rates equal to or higher than those of the current century.
  • Arctic likely to become ice-free: The Arctic Ocean is expected to become essentially ice free in summer before mid-century.


U.S. regional effects

Below are some of the impacts that are currently visible throughout the U.S. and will continue to affect these regions, according to the Third National Climate Assessment Report2, released by the U.S. Global Change Research Program:

  • Northeast. Heat waves, heavy downpours and sea level rise pose growing challenges to many aspects of life in the Northeast. Infrastructure, agriculture, fisheries and ecosystems will be increasingly compromised. Many states and cities are beginning to incorporate climate change into their planning.
  • Northwest. Changes in the timing of streamflow reduce water supplies for competing demands. Sea level rise, erosion, inundation, risks to infrastructure, and increasing ocean acidity pose major threats. Increasing wildfire, insect outbreaks, and tree diseases are causing widespread tree die-off.
  • Southeast. Sea level rise poses widespread and continuing threats to the region's economy and environment. Extreme heat will affect health, energy, agriculture, and more. Decreased water availability will have economic and environmental impacts.
  • Midwest. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air, and water quality, and more. Climate change will also exacerbate a range of risks to the Great Lakes.
  • Southwest. Increased heat, drought and insect outbreaks, all linked to climate change, have increased wildfires. Declining water supplies, reduced agricultural yields, health impacts in cities due to heat, and flooding and erosion in coastal areas are additional concerns.


1IPCC 2007, Summary for Policymakers, in Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK, p. 17.

2USGCRP 2014, Third Climate Assessment.











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