9.2 Carbon dioxide and methane as greenhouse gases

• Greenhouse gases are gases that absorb and re-emit infrared radiation.
• The greenhouse effect traps heat by absorbing and re-emitting infrared radiation.
• The re-emitted infrared radiation warms the Earth's surface creating the greenhouse effect.
• Steps of the greenhouse effect

  1️⃣ Heat energy is emitted from Earth's surface

  2️⃣ Greenhouse gases absorb infrared radiation

  3️⃣ Infrared radiation is re-emitted in all directions

  4️⃣ Earth's surface is warmed
• The greenhouse effect is a natural process that warms Earth.

  True
• What molecular property of carbon dioxide allows it to trap heat?

  Absorbs infrared radiation
• What are the two main categories of sources for carbon dioxide in the atmosphere?

  Natural and human-caused
• What is the greenhouse effect?

  Trapping heat by greenhouse gases
• Increased human emissions of carbon dioxide enhance the greenhouse effect and lead to global warming.


  True
• What human activities contribute to carbon dioxide emissions in the atmosphere?

  Burning fossil fuels, deforestation, industrial processes
• Greenhouse gases keep Earth at a habitable temperature.


  True
• Steps of the greenhouse effect

  1️⃣ Heat energy is emitted from Earth's surface

  2️⃣ Greenhouse gases absorb infrared radiation

  3️⃣ Infrared radiation is re-emitted in all directions

  4️⃣ Earth's surface is warmed
• Greenhouse gases trap heat, keeping Earth at a habitable temperature.

  True
• Where does infrared radiation originate in the greenhouse effect?

  Earth's surface
• What is the molecular structure of carbon dioxide?

  Two oxygen atoms bonded to a single carbon atom
• Carbon dioxide is a key greenhouse gas that traps heat in the atmosphere.


  True
• The burning of fossil fuels is a major human-caused source of carbon dioxide emissions.


  True
• Steps in the greenhouse effect:

  1️⃣ Infrared radiation is emitted from Earth's surface

  2️⃣ Greenhouse gases absorb the radiation

  3️⃣ Greenhouse gases re-emit the radiation in all directions

  4️⃣ The re-emitted radiation warms Earth's surface
• Name three natural sources of carbon dioxide in the atmosphere.

  Respiration, volcanic eruptions, decomposition
• The burning of fossil fuels is the primary human-caused source of increased carbon dioxide emissions.

  True
• Methane (CH4) is a key greenhouse gas that absorbs and re-emits infrared radiation
• Methane is a more potent greenhouse gas than carbon dioxide, despite being less abundant
• Greenhouse gases keep our planet at a habitable temperature by trapping heat
• Human activities are the primary source of increased carbon dioxide in the atmosphere.


  True
• Match the source of carbon dioxide with its description:

  Natural Sources ↔️ Respiration, volcanic eruptions, decomposition

  Human Activities ↔️ Burning fossil fuels, deforestation, industrial processes
• What is the molecular formula of methane?

  $CH_{4}$
• What are three key sources of methane emissions?

  Agriculture, leaks, decomposition
• Agriculture is a significant human-caused source of methane emissions.


  True
• Reducing methane emissions has a greater short-term impact on global warming than reducing CO₂ emissions.


  True
• Reducing methane emissions can substantially slow global warming in the short to medium term.

  True
• Methane, like carbon dioxide, traps heat in the atmosphere by absorbing infrared radiation.


  True
• Match the greenhouse gas with its molecular structure:

  Carbon Dioxide (CO₂) ↔️ Two oxygen atoms bonded to a single carbon atom

  Methane (CH₄) ↔️ Four hydrogen atoms bonded to a single carbon atom
• Steps of the greenhouse effect:

  1️⃣ Infrared radiation is emitted from the Earth's surface

  2️⃣ Greenhouse gases absorb the infrared radiation

  3️⃣ Greenhouse gases re-emit the radiation in all directions

  4️⃣ Re-emitted radiation warms the Earth
• Carbon dioxide's molecular structure consists of two oxygen atoms bonded to a single carbon atom
• Carbon dioxide is a key greenhouse gas that traps heat in the Earth's atmosphere.

  True
• The burning of fossil fuels is a major contributor to the enhanced greenhouse effect and global warming
• Match the greenhouse gas with its molecular structure:

  Carbon Dioxide (CO₂) ↔️ Two oxygen atoms bonded to a single carbon atom

  Methane (CH₄) ↔️ Four hydrogen atoms bonded to a single carbon atom
• What is the primary natural source of methane emissions?

  Wetlands
• What is the GWP of methane over 100 years compared to carbon dioxide?

  25
• One ton of methane has 25 times the warming impact as one ton of carbon dioxide.