Feedback loops: changes that grow or shrink themselves
Grade 9 Science Worksheet
Circle the best answer.
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?
- Positive, since it is good for plants
- Negative: it shrinks part of the rise
- Positive: carbon dioxide and plants both increase
- Negative: it removes the added carbon dioxide completely
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
- Negative, since more vapor is a bad thing
- Positive: it more than doubles the warming
“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?
- Negative, since it has − links in it
- Positive, but just because one link is +
- 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
- Positive, since plant growth is good
- Negative: one − link makes the loop −
- 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?
- Negative: one − link makes the loop −
- Negative, so the room ends up colder than the setting
- Positive, since a warm home is good
- 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
- 0.4 W/m²
- 80 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?
- 194 W/m²
- 80 W/m²
- 12 W/m², the reflected part
- 188 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?
- 268 W/m² more is absorbed
- It absorbs the same amount
- 108 W/m² more is absorbed
- 108 W/m² less is absorbed
Read this first
Arctic in late summer (model data)
Year Sea ice (million km²) Air temperature change (°C) 1985 7.5 0.0 2005 5.9 0.9 2025 3.8 2.1 Which statement do the Arctic data support, by Tala's reading?
- The ice loss was the starting forcing in 1985
- More ice went along with warmer air
- Less ice went along with warmer Arctic air
- The data show a negative loop
Yearly carbon dioxide (model data)
Flow Units per year added by people 10 taken up by extra plant growth 3 People add 10 units of carbon dioxide a year; extra plant growth takes up 3 units. How does the plant loop change the yearly rise, by Zee's math?
- From 10 to 7 units, about 30% smaller
- From 10 to 13 units
- It does not change the rise
- From 10 to 0 units; the rise stops