Greenhouse Gases & the Greenhouse Effect

1. Greenhouse Gases & the Greenhouse Effect

2. General Information • Greenhouse gases (GHG) were naturally found in the environment before the industrial revolution. • Pollution created by factories, homes, and cars, adds more greenhouse gases to the atmosphere • All greenhouse gases absorb infrared radiation (heat) • The greenhouse effect is the actual warming of the earth due to greenhouse gases. This is good because it gives the earth a temperate (warm) climate, but humans have thrown it off balance due to added greenhouse gas emissions.

3. Types of Greenhouse Gases

4. Carbon Dioxide • CO₂ • Can stay in the atmosphere for up to 120 years. • Enters the atmosphere through the burning of fossil fuels. Examples of these are crude oil, coal, and natural gas. Fossil fuels are made up of organic matter (fossils placed under extreme heat and pressure over millions of years).

5. Methane • CH₄ • Found naturally in wetlands. • It is being added to the atmosphere faster than it can be broken down through chemical processes. • Absorbs more heat than CO₂

6. Nitrous Oxide • N₂O • Occurs in the atmosphere as nitrogen is broken down. • Stays in the atmosphere up to 114 years. • Adds to global warming and the breaking down of ozone.

7. CFCs • Can stay in the atmosphere 50-100 years • Not naturally found in the atmosphere (added by humans since the industrial revolution). • No longer used in making refrigerants, fire retardents, etc.

8. Water Vapor • H₂O (gas) • Most abundant in atmosphere, but concentrations can change. • As earth warms, more water evaporates. As earth cools, less water evaporates. Therefore global warming causes more water vapor and even faster warming.

9. Impact on Climate • Greenhouse gases absorb infrared radiation given off by earth -> greenhouse effect • Once the heat is absorbed, it stays in earth’s atmosphere, heating up the earth (causing the greenhouse effect)

10. Kyoto Protocol • A treaty (an agreement not required by law) signed by most developed countries to reduce their GHG emissions. • Developed countries – agreed to reduce their GHG emissions by 5% below 1990 levels by the year 2012. • Developing countries refused to agree to these terms. They want the same chance to develop that developed countries had (i.e. using fossil fuels).

11. Global Warming

12. History • The earth naturally goes through warming (interglacial period) and cooling (glacial) depending on the levels of GHG. • Scientists use proxies to determine past climates. Examples of these are tree rings, corals, and ice cores. • The earth can quickly change between glacial periods due to the disruptions of the ocean conveyor system. • Global warming is caused by the greenhouse effect.

13. Ocean Conveyor System • Transports warm water to the deeper parts of the ocean therefore warming the bottom of the ocean. • The ocean temperature can relate to climates around the world. The conveyor system keeps the earth warmer (by transporting heat).

14. Connection to Global Dimming

15. Global Warming • GHG released into atmosphere • Sunlight (short wave radiation) absorbed by earth and it’s atmosphere • Earth absorbs short wave radiation and releases infrared radiation (long wave radiation) • GHG absorb UV radiation (heat) • GHG release heat back to earth (heats earth even more) -> global warming

16. Global Dimming • Particulate matter released into air through pollution caused by humans • Particulate matter blocks sunlight reaching earth -> global dimming

17. Connection • Global warming requires sunlight • Global dimming reduces sunlight • If particulate matter reduces sunlight, then the earth absorbs less solar radiation and emits less infrared radiation for the GHG to absorb.