Feedback loops: changes that grow or shrink themselves

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   “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
   • Not a feedback; the gases are the starting forcing
   • Negative: the thawing uses up the warming
   • Negative, since the gases are harmful
2. 2.

   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
   • Positive: carbon dioxide and plants both increase
   • Negative: it shrinks part of the rise
   • Positive, since it is good for plants
3. 3.

   “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 melting ice is bad
   • Positive, but just because one link is +
   • Positive: two − links make the loop +
   • Negative, since it has − links in it
4. 4.

   The plant loop has two links: carbon dioxide → plant growth (+); plant growth → carbon dioxide (−). What is the loop's sign, by Luz's count?

   • Negative, so carbon dioxide returns to its old level
   • Positive, since it has a + link
   • Negative: one − link makes the loop −
   • Positive, since plant growth is good
5. 5.

   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 −
   • Positive: two + links outnumber one −
   • Negative, so the room ends up colder than the setting
   • Positive, since a warm home is good
6. 6.

   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?

   • 200 W/m²
   • 120 W/m², the reflected part
   • 80 W/m²
   • 0.4 W/m²
7. 7.

   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
   • 188 W/m²
   • 194 W/m²
   • 80 W/m²

8. 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

9. 8.

   Which statement do the Arctic data support, by Tala's reading?

   • Less ice went along with warmer Arctic air
   • The data show a negative loop
   • More ice went along with warmer air
   • The ice loss was the starting forcing in 1985

10. Yearly carbon dioxide (model data)

    Flow	Units per year
    added by people	10
    taken up by extra plant growth	3

11. 9.

    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
    • It does not change the rise
    • From 10 to 0 units; the rise stops
    • From 10 to 13 units

12. Warming and water vapor (model data)

    Warming (°C)	Water vapor change (%)
    1	7
    2	14
    3	21

13. 10.

    Which pattern in the table supports a positive water-vapor loop, by Ari's reading?

    • Vapor falls as the air warms
    • Vapor rises with warming, so the loop is negative
    • Vapor rises with warming, adding more warming
    • Vapor rises, showing vapor started the warming