Feedback loops: changes that grow or shrink themselves
Grade 9 Science Worksheet
Circle the best answer.
“Loop diagram:” Warming thaws permafrost. The thawed soil releases carbon dioxide and methane, which warm the air more (NASA). What kind of loop is this, by Bo's reading?
- Positive: it amplifies the warming
- Negative, since the gases are harmful
- Not a feedback; the gases are the starting forcing
- Negative: the thawing uses up the warming
More carbon dioxide helps many plants grow more, and the extra growth takes some carbon dioxide back out of the air (NASA). What kind of loop is this, by Esme's reading?
- Negative: it removes the added carbon dioxide completely
- Negative: it shrinks part of the rise
- Positive: carbon dioxide and plants both increase
- Positive, since it is good for plants
Warmer air holds more water vapor, a greenhouse gas, which warms the air further. NASA estimates this more than doubles the warming from carbon dioxide alone. What kind of loop, by Jun's reading?
- Not a feedback; water vapor is the original cause
- Negative: the extra vapor cancels the warming
- Positive: it more than doubles the warming
- Negative, since more vapor is a bad thing
“Loop diagram:” The ice-albedo loop has these links: temperature → sea ice (−); sea ice → sunlight absorbed (−); sunlight absorbed → temperature (+). What is the loop's sign, by Kira's count?
- Positive, but just because one link is +
- Negative, since it has − links in it
- Negative, since melting ice is bad
- Positive: two − links make the loop +
The plant loop has two links: carbon dioxide → plant growth (+); plant growth → carbon dioxide (−). What is the loop's sign, by Luz's count?
- Positive, since it has a + link
- Negative: one − link makes the loop −
- Positive, since plant growth is good
- Negative, so carbon dioxide returns to its old level
A home heating loop: room temperature → thermostat calls for heat (−); call for heat → furnace output (+); furnace output → room temperature (+). What is its sign, by Milo's count?
- Positive, since a warm home is good
- Negative: one − link makes the loop −
- Negative, so the room ends up colder than the setting
- Positive: two + links outnumber one −
Sunlight of 200 W/m² falls on sea ice with an albedo of 0.6. How much does the ice absorb, by Noah's math?
- 120 W/m², the reflected part
- 80 W/m²
- 0.4 W/m²
- 200 W/m²
The same 200 W/m² falls on open ocean with an albedo of 0.06. How much does the ocean absorb, by Pia's math?
- 12 W/m², the reflected part
- 80 W/m²
- 188 W/m²
- 194 W/m²
That patch of sea ice (albedo 0.6) melts into open ocean (albedo 0.06) under the same 200 W/m². How does the energy it absorbs change, by Ren's math?
- 108 W/m² less is absorbed
- 268 W/m² more is absorbed
- It absorbs the same amount
- 108 W/m² more is absorbed
Read this first
Warming and water vapor (model data)
Warming (°C) Water vapor change (%) 1 7 2 14 3 21 Which pattern in the table supports a positive water-vapor loop, by Ari's reading?
- Vapor rises with warming, so the loop is negative
- Vapor rises with warming, adding more warming
- Vapor falls as the air warms
- Vapor rises, showing vapor started the warming