Add to table of contents: Cycle loops Pg. 80 Systems & Feedback Loops Pg. 81

SYSTEMS & FEEDBACK LOOPS Pg. 81

Systems: INPUT  matter, energy, information entering a system THROUGHPUT  rate flow of matter, energy, or information through a system OUTPUT matter, energy, information leaving a system Stuff goes in Stuff is processed Stuff comes out

Input  Throughput  Output

Feedback loops-Change induces change Stuff goes in Stuff is processed Stuff comes out

1. Negative Feedback Loops- -The change counteracts the situation. Examples: What happens when you’re hot? What happens when you’re cold?

Pesticides:

2. Positive feedback Loops- -The change compounds the situation = Snowball Effect! Example: As long as there are more human births than deaths, population will continue to increase.

Urban Sprawl

Example:Positive or Negative? 1 person in a group of 10 has cold. That person passed the cold to another and soon 5 people now have the cold. Those 5 people then each pass the cold to another.

On your paper: Number 1-5. Read the example. Answer, - Positive or Negative

On your paper: - Positive or Negative? 1. The warming of the oceans causes dissolved CO2 to bubble out into the atmosphere. This atmospheric CO2 helps to trap heat near the earth. This trapped heat continues to warm the ocean.

Positive or Negative? 2. Warmer water temperatures cause greater water evaporation, which increases the formations of clouds. A lot of water vapor in the air also traps heat inside the atmosphere.

Positive or Negative? 3. The increased cloud cover from example 2 might also act to reflect sunlight back into space, preventing it from entering our atmosphere. This might cool the earth.

Positive or Negative? 4. Sunlight striking the earth is absorbed by dark colors and reflected by light colors. The polar ice caps act like huge mirrors, reflecting sunlight back into space. Warmer water temperatures are melting these ice caps and decreasing these big “mirrors,” leaving dark water behind.

Positive or Negative? 5. Warmer temperatures cause greater water evaporation, which falls to earth as precipitation. Therefore global warming may cause increased snow fall in the polar regions, leading to increased ice formation.

How did you do?

Positive!!! Positive or Negative? 1. The warming of the oceans causes dissolved CO2 to bubble out into the atmosphere. This atmospheric CO2 helps to trap heat near the earth. This trapped heat continues to warm the ocean. Positive!!!

Positive or Negative? Positive!!! 2. Warmer water temperatures cause greater water evaporation, which increases the formations of clouds. A lot of water vapor in the air also traps heat inside the atmosphere. Positive!!!

Positive or Negative? Negative!! 3. The increased cloud cover from example 2 might also act to reflect sunlight back into space, preventing it from entering our atmosphere. This might cool the earth. Negative!!

Positive or Negative? Positive!! 4. Sunlight striking the earth is absorbed by dark colors and reflected by light colors. The polar ice caps act like huge mirrors, reflecting sunlight back into space. Warmer water temperatures are melting these ice caps and decreasing these big “mirrors,” leaving dark water behind. Positive!!

Positive or Negative? 5. Warmer temperatures cause greater water evaporation, which falls to earth as precipitation. Therefore global warming may cause increased snow fall in the polar regions, leading to increased ice formation. Negative!!!

Video clip http://ed.ted.com/lessons/feedback-loops-how-nature-gets-its-rhythms-anje-margriet-neutel

Answer essential question

Contemplate this… What would Earth look like if there weren't any greenhouse effect at all? It would probably look a lot like Mars. Mars doesn't have a thick enough atmosphere to reflect enough heat back to the planet, so it gets very cold there.

Hmmmmm…. Some scientists have suggested that we could terraform the surface of Mars by sending "factories" that would spew water vapor and carbon dioxide into the air. If enough material could be generated, the atmosphere might start to thicken enough to retain more heat and allow plants to live on the surface.

Just like early Earth… Once plants spread across Mars, they would start producing oxygen. After a few hundred or thousand years, Mars might actually have an environment that humans could simply walk around in -- all thanks to the greenhouse effect. Early earth (3.5bya) did not have oxygen. Life as we understand it didn’t start until we had plants. Prior to photosynthesis, life sustained itself with chemosynthesis and sulfur. Might pollution cause us to undergo another major evolutionary switch???? 27

How did you do? 1. Positive 2. Positive 3. Negative 4. Positive

Feedback Loops in Context Global warming hypothesizes that the average temperature of Earth is increasing. During analysis, scientists have identified possible positive and negative feedback loops to explain atmospheric climate change. http://science.howstuffworks.com/global-warming.htm

Radiation and Reflection ANALOGY: Students should think about a parked car gaining heat in its interior. The heat from the sun coming in gets trapped and makes the car hotter inside than the outside temp. What are ways to reduce that? Those reflective sun shields, cracking the windows. 30