Climate Change 101: Causes and Effects

In Part 1 of our Climate Change 101 series, we broke down what climate change is and started touching on why it’s such a big deal -- we recommend giving that post a read first if you want to brush up on this topic. This week, we’re delving deeper into the (rapidly warming) waters of climate change and getting into the nitty gritty of what factors are contributing to the climate crisis and what some of the resulting impacts will look like on our world.

Greenhouse Gases That Contribute to Climate Change & Their Causes


Greenhouse Gas Emissions by Source

Greenhouse Gases:

  • Water Vapor: Water Vapor is often overlooked but arguably the most important greenhouse gas because it’s the largest contributor to the greenhouse gas effect and is ultimately responsible for 60% of warming. However, water vapor would not be a problem in itself if not for the other greenhouse gases contributing to its increase and subsequent warming of the atmosphere. The other gases cause the temperature of vapor to rise, creating a positive feedback effect as the water vapor then increases in volume and heightens the impacts of the other gases. (Source: American Chemical Society)


Carbon dioxide emissions pie chart


  • Carbon Dioxide: Carbon dioxide naturally exists in the atmosphere through processes such as volcanic eruptions and respiration, but humans have increased the concentration of carbon dioxide in the atmosphere by 47% since the Industrial Revolution began through activities such as deforestation and the burning of fossil fuels (coal, oil, and natural gas) for transportation, energy, and industrial processes. (Source: NASA



  • Methane: Methane is also both naturally occurring and has seen an increase resulting from human activities. While it has a shorter lifetime in the atmosphere than carbon dioxide, it has 25 times the impact of CO2 over a 100-year period because it is much more efficient at trapping heat. The primary sources of methane include leaks from natural gas and petroleum systems, enteric fermentation from the raising of domestic livestock, landfill waste, and natural wetlands. (Source: EPA)


Emissions by Nitrous Oxide Sources


  • Nitrous Oxide: This powerful greenhouse gas is primarily produced by soil cultivation practices, including synthetic and organic fertilizers and manure as well as the burning of agricultural residues and makes up 77.8% of total U.S. nitrous oxide emissions. Other contributors include fuel combustion, the treatment of domestic wastewater, and the production of certain chemicals like those to make synthetic fertilizers as well as synthetic textiles like nylon.


Emissions by Fluorinated Gases


  • Fluorinated Gases, including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3): These are the only greenhouse gases that have no natural sources and result entirely from human activities. The primary sources are from refrigerants and a variety of industrial processes including the manufacture of aluminum and semiconductors.

Effects of Climate Change

The impact of climate change touches all of life on this planet. The delicate balance of each and every ecosystem is at risk, and many are already seeing detrimental effects -- from disappearing Arctic ice to dying coral reefs to insect infested and wildfire ravaged forests. All the species who depend on that balance will be forced to adapt to a very different new normal, including humans.

The average global temperature of the planet has warmed 1 degree Fahrenheit since the Industrial Revolution. The body of 1,300 scientists from around the world called the Intergovernmental Panel on Climate Change predicts that the temperature will increase 2.5 to 10 degrees Fahrenheit over the next century. (Source: NASA) To put this in perspective, the global temperature was just 9 degrees cooler during the Ice Age. That seemingly slight shift in temperature will and already is having serious consequences. Here are some of the ones that will most affect humans:

  • Sea level rise: "Global sea level has been rising over the past century, and the rate has increased in recent decades. In 2014, global sea level was 2.6 inches above the 1993 average—the highest annual average in the satellite record (1993-present). Sea level continues to rise at a rate of about one-eighth of an inch per year,” according to the National Ocean Service. This is caused by two factors: 1) warmer ocean temperatures cause the water to expand, and 2) melting land ice, including ice sheets and glaciers, are melting, which adds to the overall volume of ocean water. This is pretty problematic considering 8 of the 10 most populous cities in the world are in coastal areas, including 40% of the population in the United States. 

  • Ocean acidification: The oceans absorb 90% of the atmospheric heat resulting from human activity-derived emissions, and that heat is resulting in dramatic changes to many oceanic ecosystems. The ocean also ends up absorbing a third of all carbon emissions, which has caused it to be 40% more acidic than it used to be. (Source: Environmental Defense Fund) Bad news for seafood lovers and the other species that depend on these ecosystems. 
  • Extreme weather conditions: The increased evaporation of water due to the heat also exacerbates extreme weather events like hurricanes while also causing a general increase in precipitation, including rain and snow storms resulting from more moisture in the air. At the same time, higher temperatures in dryer areas also cause the limited moisture to evaporate more quickly leading to droughts and dangerous wildfire conditions, in addition to longer and more extreme heat waves. (Source: Environmental Defense Fund)
  • Water and Agriculture: Those same conditions will also impact water availability in various regions, with many areas experiencing severe drought. This not only affects the availability of clean drinking water, but the viability of local agriculture in many regions. On top of that, climate change will also increase the likelihood of pests, weeds, diseases, and flooding that can threaten crop yields. (Source: Environmental Defense Fund) These factors are likely to result in mass migrations and geopolitical conflicts over limited resources.
  • Pollution: Human health is also at risk due to a variety of sources of pollution. “A warmer atmosphere increases the formation of ground-level ozone – also known as smog – in polluted regions,” according to the Environmental Defense Fund. Smog, in addition to other environmental pollutants like smoke from wildfires, can irritate the lungs and trigger asthma attacks. Warmed temperatures in the summer also create fertile breeding grounds for bacteria in our drinking water to thrive. 

Major bummer, right? Well the good news is that human-caused problems can also have human-generated solutions! Stay tuned for Part 3 of this series where we’ll share the most impactful actions we can take to mitigate the effects of climate change and contribute to a more livable world. 

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