50+ Consequences of Global Warming

As a middle school science teacher, one of my imperatives is to ensure that students understand the causes and consequences of global warming.

There are about a million articles on Global Warming, but few that discuss the huge range of observed and potential consequences. Perhaps because the consequences are so vast, articles tend to tackle only a few "parts of the elephant" at a time: one article focuses on sea level change, another on heat waves, yet another on vanishing polar bear habitat, etc.

As a result, I have now created my own list, which has come in so handy as a resource for the science class I teach that I am posting it here.

Some of these are consequences are obvious, but some of them are decidedly more surprising, subtle, or less well understood.  (For example: did you know that global warming is linked to earthquakes? navigation? civil war?) I do think it's critical that students understand the range and significance of consequences that we are already beginning to observe as a result of this phenomenon.

Loss of Icepack
  1. Habitat Loss. Loss of habitat for polar-ice edge populations such as indiginous humans (Inuit villages), penguins, seals, and polar bears is perhaps the most obvious consequence of icepack destruction. 
  2. Earthquakes/tsunamis. How will global warming lead to more earthquakes, you ask? Being extremely heavy, massive glaciers apply a considerable amount of pressure to the Earth’s surface underneath them. This anchorage decreases as the glaciers diminish, resulting in a ‘loosening’ of tectonic masses that can lead to massive earthquakes which are capable of creating deadly tsunamis.  Don't believe me?  Michigan is still experiencing earthquakes triggered by the melting of glaciers that buried that area during the last ice age.
  3. Increased Volcanic Activity. The shifting pressures brought about by the lightening of the vast ice sheets allows the Earth’s crust to ‘bounce back’ and can cause eruptions in unexpected places – like the one experienced during Iceland's Gjálp eruption, where magma reached the surface at an unusual intermediary point between two volcanoes. Potent or sustained volcanic activity can have an immense impact on human life even if the activity is centred away from dense population centres. It also has the potential to affect the planet’s climate by injecting tons of gases and solids into the atmosphere that can remain there for weeks
  4. Increase in rate of global warming. Ice caps are white and therefore reflect sunlight, much of which is reflected back into space, further cooling Earth. If the ice caps melt, the only reflector is the ocean. Darker colors absorb sunlight, further warming the Earth.  So, basically, what we're saying is that one of the impacts of global warming is faster global warming.  Ironic, isn't it?
  5. Decrease in fresh water supplies on land. Many of the world's most important rivers are fed by glaciers, and - after a few years of perilous flooding - will begin inevitably to shrink as the source of their water vanishes.  The Himalayan glaciers that feed the Ganges River, which supplies drinking and irrigation water to 500 million people, are reportedly shrinking by 40 yards (37 meters) each year, and if the Quelccaya ice cap in Peru continues to melt at its current rate, it will be gone by 2100, leaving thousands of people who rely on it for drinking water and electricity without a source of either.
  6. Exploitation of New Resources. As icepacks melt, new sources of oil and gas may be rendered exploitable, potentially igniting political/military instability and altering the global commodity markets. You have to wonder how long the Antarctica Treaty of 1961 - which states that no country may stake a claim to the territory -  is going to last if significant deposits of oil or minerals are discovered beneath the ice.
  7. Changes to navigation.  Global warming will have both positive and negative impacts on shipping.  While melting of surface ice will open new navigation routes (Russian ships are already exploiting newly opened navigation channels), other shipping will be placed at risk by the increased number of icebergs spawned by "calving" glaciers that drift into areas where they have are not customarily found.
Increase in Ocean Temperatures/Decreases in Ocean Salinity. Our ice caps are huge fresh water reservoirs; as they melt, the influx of fresh water into marine biomes will significantly reduce levels of salinity (and, in turn, density).  Meanwhile, ocean temperatures will increase, with greatest warming over land and high northern latitudes, and least over the Southern Ocean and parts of the North Atlantic Ocean.
  1.  Impacts on weather. Fresh water is less dense than salty water; this density differential will trigger potentially massive shifts in ocean currents, including currents that regulate temperature - like El Nino and la Nina.  Irregularities in these currents will, in turn, result in huge global shifts in climate.
  2. Impacts on ecosystems.  Shifts in temperature and salinity will irrevocably alter ocean ecosystems.  Animals will either have to adapt or perish.  Perhaps the most frightening prospect is ongoing reduction of phytoplankton. These tiny plants are an integral food source for ocean life and are responsible for around half of the world’s photosynthetic activity. Essentially, they are the foundations of the oceanic food chain, so a reduction in their numbers creates a knock-on effect that ripples up the entire food chain, particularly affecting the predators at the top.  A strong connection between oceanic warming, declines in reproduction and increases in mortality rates among seabirds, seals and sea lions has already been observed.
  3. Eutrophication.  Increases in amounts of sun, increased nutrients in the water due to runoff/erosion of agricultural lands, and warming temperatures may trigger extreme overgrowths of algae, also known as "algae blooms".  These algae blooms trigger eutrophication, the process whereby excessive algae blooms block sunlight and deoxygenate aquatic environments, leading to large-scale marine extinction events.
  4. Economic impacts. As salinity changes cause currents to shift and habitats to be disrupted, this will have a huge impact on any number of industries, to include:
    1. Fishing.  Many countries and regions rely on fishing both for food and for economic sustainance.  As populations of aquatic animals become unstable - species moving to new locations or dying off - these communities will face grave economic hardships.
    2. Navigation.  Shipping relies on established wind and current patterns.  Alterations in these currents will impact shipping, recreational cruising, and naval defense. 
Melting Ice/Rising Sea Levels. As the Earth heats up, sea levels rise because warmer water takes up more room than colder water, a process known as thermal expansion. Melting glaciers compound the problem by dumping even more fresh water into the oceans.  Rising seas threaten to inundate low-lying areas and islands, threaten dense coastal populations, erode shorelines, damage property and destroy ecosystems such as mangroves and wetlands that protect coasts against storms.  According to the National Snow and Ice Data Center, if all glaciers melted today the seas would rise about 230 feet.
  1. Destruction of coastal cities and towns. An increase of just a single meter (3 ft) would submerge considerable sections of the U.S. eastern seaboard, while one sixth of Bangladesh could be lost permanently by a rise of 1.5 m (5 ft), to name just two examples.
    1. Destruction of important coastal cities.  In the developed world, 35 of the 40 largest cities are either coastal or situated along a river bank. In Europe, rivers have played a more important role in determining the growth and importance of a city than the sea; more than half of the 20 largest cities in the region developed along river banks.  Here's a partial list of coastal cities likely to be swamped by rising sea temperatures: Mumbai, Shanghai, Miami, New York City, Alexandria, and New Orleans.  Think of the havoc this will wreak on worldwide economic markets, on geopolitical stability, on universities, museums, culture, and society.
    2. Destruction of important economic assets.  Besides cities, rising sea levels would also devastate ports, harbors, fishing villages, beach towns, and industries strategically located along rivers/oceans in order to facilitate energy (hydroelectric plants), water (nuclear power plants), or transportation needs.
    3. Destruction of cultural assets.  Since ancient civilizations were almost always located adjacent to water sources, many of our most significant archeological sites are likely to be submerged.  Floods attributed to global warming have already damaged a 600-year-old site, Sukhothai, which was once the capital of a Thai kingdom.  And although the ruins of Pompeii survived a massive volcanic eruption, they may not survive global warming. 
  2. Destruction of Coastal Habitats.  Apart from the destruction of human habitations, rising sea levels will decimate habitats that exist at sea level - notably wetlands and estuaries.  These habitats serve countless crucial functions: filtering water, providing habitat for crustaceons and other animals, providing critical "rest stops" for migrating birds, protecting coastlines from the dangers of storm surges (ironic, isn't that?).  In time natural processes will presumably replace these assets, but it won't happen in time to prevent potentially devastating consequences to water quality and coastal life. 
  3. Mass Human Migration.  Worldwide, approximately 100 million people live within three feet of sea level. Sea level rise associated with climate change could displace tens of millions of people in low-lying areas – especially in developing countries. Inhabitants of some small island countries that rest barely above the existing sea level are already abandoning their islands, some of the world’s first climate change refugees.
  4. More Intense Hurricanes & Flooding.  Higher sea levels will exacerbate storm surges, flooding, and erosion.
Extreme weather.  Climate change is intensifying the circulation of water on, above and below the surface of the Earth, impacting global weather patterns and related phenomenon.
  1. Precipitation.  Scientists predict increased precipitation in higher latitudes but significantly descreased precipitation in lower (subtropical) latitudes. 
  2. Floods.  Warmer temperatures increase the energy of the climatic system and can lead to heavier rainfall in some areas. Scientists project that climate change will increase the frequency of heavy rainstorms, putting many communities at risk for devastation from floods.
  3. Drought. As the climate warms, experts estimate drought conditions may increase by at least 66 percent. Water is already a dangerously rare commodity in Africa. The Intergovernmental Panel on Climate Change suggests that by 2020, 75 to 250 million Africans may experience water shortages, and the continent's agricultural output will decrease by 50 percent.
  4. Fires. Hot, dry weather and increased evaporation led to a record-setting 2006 wildland fire season in the U.S., with close to 100,000 fires reported and nearly 10 million acres burned, 125 percent above the decade's average.
  5. Extreme storms (hurricanes/cyclones/tornadoes). Scientific research indicates that climate change will cause hurricanes and tropical storms to become more intense — lasting longer, unleashing stronger winds, and causing more damage to coastal ecosystems and communities.  The culprit is warmer ocean waters, which pump more energy into tropical storms, making them stronger and potentially more destructive.
  6. Heat Waves. Extreme heat waves are happening two to four times more often now, steadily rising over the last 50 to 100 years, and are projected to be 100 times more likely over the next 40 years.   In fact, the five hottest years on record have all occurred since 1997 and the 10 hottest since 1990, including the warmest years on record – 2005 and 2010.
  7. Cold Waves. Seems ironic that global warming causes more extreme cold, but changes in atmospheric patterns brought about by receding glacial ice can lead to the redirection of polar air currents and the sun's rays being absorbed by the larger areas of dark blue sea.
  8. Acid Rain. More greenhouse gases in the atmosphere create more acidic rain.  Not acidic enough to burn the skin off bones, perhaps, but enough to impact vulnerable species.  One example of this is the death of large amounts of snails in areas prone to acidic precipitation. Birds dependent upon the snails as a calcium-rich food source and, without a suitable replacement for this loss to their diet, lay eggs with a much higher amount of defective shells.  Over time, acidic rains will also damage man-made structures.
  9. Economic consequences of extreme weather.  Storms cause huge economic damages. Government, industry, individuals, and the insurance industry bear the cost of replacing damaged infrastructure, damaged industry, and devastated agricultural areas.  One way or another, those costs end up being passed on to individuals, either through taxes, job loss, or higher insurance premiums.
  10. Population consequences of extreme weather. As cities are destroyed by catastrophic events, ans as insurers like State Farm begin to refuse coverage to folks living in areas vulnerable to extreme weather events, cities will be abandoned and those citizens will relocate elsewhere.
  11. Social consequences of extreme weather.  Extreme weather events - hurricanes, tornadoes, floods, fires, etc. - destroy entire communities and cultures.  Imagine the cultural consequences of floods destroying Venice, tornadoes devastating London*, or a hurricane wiping out New York City once and for all.  (*The U.S. may experience more tornadoes per year, but the U.K. actually averages more tornadoes per km2 per year.)
Health.  A study by the World Health Organization (2009) estimated the effect of climate change on human health. Not all of the effects of climate change were included in their estimates; for example, the effects of more frequent and extreme storms were excluded. Climate change was estimated to have been responsible for 3% of diarrhoea, 3% of malaria, and 3.8% of dengue fever deaths worldwide in 2004. Total attributable mortality was about 0.2% of deaths in 2004; of these, 85% were child deaths.  Expect these numbers to increase exponentially as the effects of global warming become more severe and widespread.

  1. Death from heat.  More frequent and severe heat waves will result in a greater number of heat-related deaths.  We're not talking a few senior citizens in un-airconditioned apartments, either: in 2010, a Russian heatwave resulted in over 56,000 deaths, and in 2003 a European heat wave was blamed for over 70,000 deaths.
  2. Famine. Prolonged drought in East Africa caused tens of thousands of deaths in 2011, with 13 million humans currently at risk of starvation due to famine. 
  3. Death from Extreme Weather (storms, floods). A warmer atmosphere can hold -- and dump -- more moisture, contributing to more intense extreme weather events, which in turn put people's lives at risk.  Maybe you're thinking about Hurricane Katrina, which killed over 1800 people?  Forget that and wrap your head around this one; in 2008, Cyclone Nargis killed over 138,000 people in Burma ... which, by the way, was the same year that almost 1000 people died as the result of a freakish blizzard in Afghanistan. 
  4. Disease.  The Deadly Dozen are a group of 12 diseases that have been identified as those most likely to spread due to global warming. They include avian influenza, cholera, plague, ebola and tuberculosis. 
    1. More water-borne diseases. Cholera and mosquito-borne diseases such as dengue fever and malaria are all thriving as the Earth warms. In Bangladesh, for example, a rise in water temperature has been observed to increase the risk of cholera outbreak by two to five times. 
    2. More pest-borne diseases. Reports of Lyme disease have risen seven-fold in Maine and four-fold in Wisconsin over the last decade as warmer temperatures expand the range and persistence of the disease.
    3. More corpse-borne diseases.  Research has shown that a handful of deadly plagues are capable of surviving for hundreds of years in the corpses of deceased carriers.  Recent discoveries reveal the possibility that long-dormant diseases like smallpox could re-emerge as the ancient dead, their corpses thawing along with the tundra, get discovered by modern man.
  5. Asthma. Global warming could increase smog pollution in some areas and intensify pollen allergies and asthma. Hotter conditions could also aggravate local air quality problems, already afflicting more than 100 million Americans. What's more, the carbon dioxide and ‘black carbon’ (a very fine soot) released by these large-scale fires together with the deforestation they cause further compounds the problem of air pollution – as the gases that help to create the greenhouse effect are supplemented and less mature trees survive to draw CO2 from the atmosphere.
  6. Animal attacks.  As competition for resources and habitats increases, expect more human vs. animal encounters - many of which will not turn out happily for the humans.  Need examples? When drought recently struck, Kenya’s Amboseli National Park, lions began to venture out of the park in search of prey.  In India, tigers driven out of mngrove forests have begun menacing humans.  Meanwhile, all over the world, sharks are moving into new areas to find stable food sources.  Think about that the next time you're at the beach.
  7. Economic impacts.  Governments, charities, insurance companies and private individuals bear the economic cost of treating health issues exacerbated by global warming ... and I'm pretty sure more shark attacks aren't going to help the beachfront tourism industry either!
Seasonal Creep. In Europe, season creep has been associated with the arrival of spring moving up by approximately one week in a recent 30 year period. Other studies have put the rate of season creep measured by plant phenology in the range of 2–3 days per decade advancement in spring, and 0.3–1.6 days per decade delay in autumn, over the past 30–80 years.
  1. Premature snowmelt.  Modeling of snowmelt predicted that warming of 3° to 5°C in the Western United States could cause snowmelt-driven runoff to occur as much as two months earlier, with profound effects on hydroelectricity, land use, agriculture, and water management.
  2. Disrupted Patterns of Interdependence. Due to seasonal creep, species that depend on one another may become out of sync. For example, plants could bloom earlier than their pollinating insects become active, and migrating animals may discover traditional food sources unavailable.
Flora.  In the tundra, thawing permafrost will allow shrubs and trees to take root. In the Great Plains of the United States, grasslands will likely become forests. And New England’s fiery fall foliage will eventually fade as maple and beech forests shift north toward cooler temperatures.  But that's just the beginning ...
  1. Desertification. How global warming affects desertification is not entirely understood, yet it is clear that an elevation in atmospheric and ground-level temperatures is likely to aggravate soil and vegetation loss in already hot climates. An increase in evapotranspiration and the accompanying decrease in rainfall means that already semi-arid and sub-humid areas found across the world will face a future barrenness that is almost irreversible.
  2. Higher Productivity.  As temperatures warm, precipitation increases, and more CO2 becomes available in the atmosphere, some agricultural areas may benefit.  Moreover, The agricultural growing season has also expanded by 10–20 days over the last few decades, and will probably continue to expand, enabling farmers to grow more crops.
  3. Lower Productivity.   Alternatively, high temperatures cause plants like rice, corn and wheat to grow faster but reduce plant fertility and grain production. With average growing-season temperatures expected to rise more than 6 degrees F in many places, crop yields will fall 20 to 40 percent, the recent report estimates. The effects will be aggravated by increased evaporation and loss of soil moisture.
  4. Maladaptation.  Shorter and warmer winters may affect environmental adaptations including cold hardening of trees, which could result in frost damage during more severe winters.
  5. Pests. As temperatures grow warmer, pest populations that have traditionally been limited by cold temperatures will increase unchecked.  Need an example? Since 1996, bark beetles have laid waste to 65,000 square miles of U.S. forest – an area roughly the size of Washington State. Scientists believe a main reason is that winters have not been cold enough to control their numbers.

  1. Loss of biodiversity. Species loss and endangerment is rising along with global temperatures. As many as 30 percent of plant and animal species alive today - over 1 million species in all - risk extinction by 2050 if average temperatures rise more than 2 to 11.5 degrees.  (And since everyone wants to know about polar bears, here it it - if current climate patterns remain unaltered, polar bears may become extinct in less than 100 years.)
    1. Wine. Not for nothing, it may soon be time to bid adieu to Bordeaux.  Researchers predict a two-thirds fall in production in the world's premier wine regions because of climate change. The study forecasts sharp declines in wine production from Bordeaux and Rhone regions in France, Tuscany in Italy, and Napa Valley in California and Chile by 2050, as a warming climate makes it harder to grow grapes in traditional wine country.
  2. Destruction of coral reefs. The ocean will continue to become more acidic due to carbon dioxide emissions. Because of this acidification, species with hard calcium carbonate shells are vulnerable, as are coral reefs, which are vital to ocean ecosystems. Scientists predict that a 3.6 degree Fahrenheit increase in temperature would wipe out 97 percent of the world's coral reefs.
  3. Shifting Habitats & Migration Patterns.  As habitats alter, animals may need to relocate to new ecosystems.  Wildlife researchers have noted some more resilient species migrating to the poles to maintain their needed habitat; the red fox, for example, normally an inhabitant of North America, is now seen living in the Arctic. And roughly 60% of more than 300 species of North American birds already are wintering farther north, some hundreds of miles from their former range. Several U.S. states may even lose their official birds as they head for cooler climates — including the Baltimore oriole of Maryland, black-capped chickadee of Massachusetts, and the American goldfinch of Iowa.
  4. Disease. Humans aren't the only ones susceptible to parasites.  Warmer temperatures will also allow the spread of parasites that target animals.  For instance, in southern New England lobster catches have plummeted because of heat stresses and growing parasite threats due to rising sea temperatures. 
Global Political/Economic consequences. The consquences listed below are in addition to those already mentioned.
  1. Higher prices for food, water, land and energy/infrastructure.  Higher prices for critical human necessities will inordinately impact our poorest populations and may, in some cases, lead to mass human migrations, unrest, and/or war.  National security experts analyzing the current conflict in Sudan's Darfur region suggest that while global warming is not the sole cause of the crisis, its roots may be traced to the impact of climate change, specifically the reduction of available natural resources. The violence in Darfur broke out during a time of drought, after two decades of little-to-no rain along with rising temperatures in the nearby Indian Ocean
  2. Competition for Scarce Resources.  Even countries without a recent history of conflict may find themselves casting a covetous eye at their neighbor's resources - usable ports, drinking water, transportation routes - should their own be devastated due to consequences of global warming.
  3. Competition for Emerging Resources.  As the Arctic ice opens up, the world turns its attention to the resources below. According to the U.S. Geological Survey, 30 percent of the world's undiscovered natural gas and 13 percent of its undiscovered oil are under this region. As a result, military action in the Arctic is heating up, with the United States, Russia, Denmark, Finland, Norway, Iceland, Sweden and Canada holding talks about regional security and border issues. Several nations, including the U.S., are also drilling troops in the far north, preparing for increased border patrol and disaster response efforts in a busier Arctic.
  4. Stiffling of Sustainable Development.  Climate change is expected to impinge on sustainable development of many emeging economies as rapid urbanization, industrialization and urban development compound pressures on natural resources and the environment.
  5. Reduced Tourism.  Both summer and winter tourism will be impacted: summer tourism by the disappearance of beachside resorts, winter tourism by the disappearance of snowpacks.
  6. Mass Human Migration.  As regions of the Earth become uninhabitable, populations that inhabit those regions will flood into neighboring regions, triggering political/religious/ethnic instability and taxing potentially overtaxed resources in the host nations.
  7. Less Money Available for Foreign Aid.  A recent study conducted by the Global Development and Environment Institute at Tufts University suggests that inaction in the face of global warming crises could result in a $20 trillion price tag by 2100.  Money spent fixing national problems is, necessarily, money unavailable to invest in foreign aid. 
  8. Increased Risk of Singularities.  A "singularity" is an abrupt, discontinuous, typically unforeseen event - think aliens landing on the lawn of the White House, or an asteroid slamming into London.  As the effects of global warming are felt, the odds increase that Earth will experience one or more large-scale "singularities" - for instance, massively accelerated climate change, pandemics, catastrophic environmental/ecological damage, or nuclear events. 


  1. I have come to the conclusion that we all have a little blame global warming and its consequences and guilt even more politicians who do not slow down.


  2. With apologies to ML King, we will either all cook together as fools or cool together as brothers and sisters.