Earth's five systems and how they affect each other

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Absorbed sunlight (model values)

   Surface	Absorbed (W/m2)
   Sea ice	80
   Open water	188

2. 1.

   Ice cover shrinks from 60% to 40% of a region. Bo averages the absorbed sunlight. What changes, and what sign is the loop?

   • About 22 W/m2 more is absorbed, but warm water (hydrosphere) first creates the ice
   • About 22 W/m2 more is absorbed: a positive feedback, since less ice means more warming
   • About 22 W/m2 more is absorbed: a negative feedback, since less ice means more cooling
   • About 108 W/m2 more is absorbed: a positive feedback, since less ice means more warming

3. Permafrost site (example data)

   Year	Thawed layer (cm)	Carbon released (g C per m2 per year)
   2000	40	30
   2020	75	60

4. 2.

   Jun reads the table. Which description of the loop fits, and by what factor did carbon release change?

   • Positive: warming deepens thaw and microbes release more carbon; release rose 30 times
   • Positive: warming deepens thaw and microbes release more carbon, which adds warming; release doubled
   • Positive: carbon in the air first thaws the ground, and microbes then respond; release doubled
   • Negative: warming deepens thaw and microbes release more carbon, which cools the air; release doubled

5. Card

   Rock weathering removes 240 million tonnes of CO2 a year. Each 1 degree C of warming speeds weathering by 5 percent (model).

6. 3.

   The climate warms 2 degrees C. Luz finds the extra CO2 removed each year and the sign of the loop.

   • About 25 million tonnes more, a positive loop: extra removal adds more warming
   • About 12 million tonnes more, a negative loop: extra removal cools the climate
   • About 265 million tonnes more, a negative loop: extra removal cools the climate
   • About 25 million tonnes more, a negative loop: extra removal cools the climate
7. 4.

   Melting about 360 billion tonnes of land ice raises sea level by about 1 mm. A glacier system loses 540 billion tonnes of ice in a year. Milo converts it. What sea-level rise and which arrow fit?

   • About 0.67 mm a year, from the cryosphere to the hydrosphere
   • About 1.5 mm a year, from the cryosphere to the hydrosphere
   • About 150 mm a year, from the cryosphere to the hydrosphere
   • About 1.5 mm a year, from the hydrosphere to the cryosphere

8. A forest's carbon in one year (example data)

   Item	Amount
   Carbon taken in by trees	6.0 t C per ha
   Carbon returned by soil and respiration	5.5 t C per ha
   Forest area	200 ha

9. 5.

   Ren finds the net CO2 removed from the air in a year. A carbon atom has mass 12 and CO2 has mass 44.

   • About 4,400 tonnes of CO2, matter moving from the atmosphere to the biosphere
   • About 100 tonnes of CO2, matter moving from the atmosphere to the biosphere
   • About 367 tonnes of CO2, matter moving from the atmosphere to the biosphere
   • About 367 tonnes of CO2, matter moving from the biosphere to the atmosphere
10. 6.

    Ice has a density of 917 kg per m3, and melting takes 334 kilojoules per kg. Extra absorbed sunlight is 22 W/m2. How long does Tala say it takes to melt 1 m of ice, and what flows?

    • About 160 days, with energy flowing from the ice into the sunlight
    • About 16 days, with energy flowing from sunlight into the ice
    • About 160 days, with energy flowing from sunlight into the ice
    • About 1,600 days, with energy flowing from sunlight into the ice

11. Card

    Methane traps 28 times as much heat as CO2 over 100 years. A thawing area of 1 km2 (1,000,000 m2) releases 2 g of methane per m2 in a year.

12. 7.

    Zee converts the release to CO2 equivalent. How many tonnes is it, and what moves?

    • 56 tonnes of CO2 equivalent, matter moving from frozen ground to the atmosphere
    • 56,000 tonnes of CO2 equivalent, matter moving from frozen ground to the atmosphere
    • 56 tonnes of CO2 equivalent, matter moving from the atmosphere to frozen ground
    • 2 tonnes of CO2 equivalent, matter moving from frozen ground to the atmosphere

13. A bay after fertilizer runoff (example data)

    Measure	Spring	Summer
    Nitrate (mg/L)	0.5	3.0
    Chlorophyll (micrograms per liter)	4	40
    Bottom oxygen (mg/L)	8.0	1.5

14. 8.

    Hypoxia is oxygen below 2 mg/L. Esme reads the table. Which chain fits, and is the bay hypoxic?

    • Nitrate feeds algae, whose decay uses up bottom oxygen; 1.5 mg/L is hypoxic
    • Low oxygen starved the algae, which then released the nitrate; 1.5 mg/L is hypoxic
    • Algae add oxygen to the bottom water, so 1.5 mg/L is healthy for fish
    • Warm summer water alone raised the chlorophyll; nitrate played no part, and 1.5 mg/L is hypoxic
15. 9.

    Note: Sunlight on the snow is 250 W/m2. Wildfire smoke drops soot on snow. Ari compares absorbed sunlight. Which chain fits, and what happens to absorption?

    • Fire (biosphere) puts soot in the air, which darkens snow (cryosphere); absorption doubles to 75 W/m2
    • Soot darkens the snow (cryosphere), which lights the fire (biosphere); absorption doubles to 75 W/m2
    • Smoke in the air darkens the snow; the fire is not part of the chain, and absorption rises 15%
    • Fire (biosphere) puts soot in the air, which darkens snow (cryosphere); absorption doubles to 37.5 W/m2

16. A river delta (example data)

    Measure	Value
    Sediment reaching the delta before dams	100 million tonnes a year
    Sediment reaching the delta after dams	20 million tonnes a year
    Delta surface sinking	5 mm a year
    Sea level rising	3 mm a year

17. 10.

    People build dams on the river. Pia reads the table. How fast does the sea rise relative to the delta, and why?

    • 3 mm a year, since dams trap sediment and the delta cannot build up
    • 8 mm a year, since the rising sea alone is drowning the delta
    • 2 mm a year, since dams trap sediment and the delta cannot build up
    • 8 mm a year, since dams trap sediment and the delta cannot build up