Introduction

Terms to Know

Before you begin this course, there are some terms to know.

• Emission: An emission is a substance released into the atmosphere. In this context, emissions are typically made up of greenhouse gasses and other harmful toxins.
• Fossil Fuel: A fossil fuel is a generic term for organic material (from decayed plants and animals) that has been exposed to heat and pressure from the earth’s crust for hundreds of millions of years and converts into oil, coal, or natural gasses.
• Wicked Problem: A wicked problem is one that has many interconnected and dependent factors that makes it seem impossible to solve. Many parts of the problem are hard to define, complex, changing, and incomplete. Climate change is an example of a wicked problem.
• Weather: Weather is the atmospheric condition at a given time or place, measured in terms of wind, temperature, cloudiness, and precipitation. Weather can be measured on different time scales such as minutes, hours, or days.
• Climate: Climate refers to the average weather and patterns measured over a defined period of time, such as a number of years, decades, or centuries.
• For an analogy, if weather were individual meals, climate would be the overall, long-term diet.

‍

Greenhouse Gasses

Greenhouse gasses (GHGs) are gasses that trap heat in the Earth’s atmosphere. They do this by absorbing infrared radiation.

The major GHGs are made of 3 or more atoms, held loosely together. When they absorb heat, they vibrate. When the molecules stop vibrating, their radiation is absorbed by other GHG molecules, keeping most of the heat in the atmosphere.

‍

Examples of Greenhouse Gasses

• Carbon Dioxide (CO₂): Carbon dioxide is a naturally occurring gas and is a byproduct of burning fossil fuels and biomass (e.g. industrial processes). It can also be a byproduct of chemical reactions (e.g. the manufacturing of cement). The earth’s radiative balance is largely attributed to CO₂.
• Methane (CH₄): Methane results from the production and transport of coal, natural gas, and oil. Livestock, agricultural practices, land use, and organic waste decaying in landfills also emit methane.
• Nitrous Oxide (N₂O): Nitrous oxide is created during agricultural, land use, and industrial activities. N₂O is released from activities such as burning fossil fuels and solid waste, as well as wastewater treatment.
• Perfluorochemicals (PFCs): PFCs are a group of chemicals used to make coatings and products that resist oil, heat, stains, grease, and water (e.g., clothing, furniture, packaging, wire insulation). The chemicals accumulate in the environment and do not break down naturally.
• Hydrofluorocarbons (HFCs): HFCs are a group of chemical gasses used in refrigeration, air conditioning, aerosols, fire extinguishers, and building insulation. These chemicals destroy ozone molecules in the atmosphere.
• Nitrogen Trifluoride (NF₃): Nitrogen trifluoride is produced while manufacturing products like semiconductors, certain types of solar panels, and flat screen LCDs. This greenhouse gas is one of the most potent, remaining in the atmosphere for around 740 years.
• Sulfur Hexafluoride (SF₆): SF₆ is commonly used in electric power systems. The structure of the molecule is extremely stable, allowing it to be used for electrical insulation and circuit breakers. According to the Environmental Protection Agency (EPA), approximately 70 percent of all SF₆ emissions in the US are attributed to the electrical transmission and distribution sector. This greenhouse gas is the most potent known to date.