Teacher sheet · Ages 15–16 · about 45–50 minutes
Polar ice, albedo and sea level
Lesson page: echoesof.science/school/polar-regions/ages-15-16/ · Pupil worksheet: echoesof.science/school/polar-regions/ages-15-16/print/
Learning aims
- Explain why the poles are cold and what polar day and night are.
- Define albedo and explain the ice-albedo positive feedback.
- Use satellite data to link ice loss to sea-level rise, with uncertainty.
- Measure the effect of surface colour on heating and calculate energy with Q = m c ΔT.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: does an ice cube melting in a full glass make it overflow? Link to sea ice versus land ice. |
| 10 min | Read the text; gigaton and percentage calculations. |
| 20 min | Albedo practical with readings every 2 minutes. |
| 5 min | Land ice or sea ice? game. |
| 5 min | Quiz; discuss the different Arctic and Antarctic trends. |
Materials for the experiment
- Two identical small beakers or cans
- White paper and black paper, sticky tape
- Measuring cylinder and water
- Two thermometers or temperature probes
- Desk lamp with a filament or halogen bulb (or strong sunlight)
- Ruler
- Stopwatch
- Optional: two equal ice cubes on white and black card
Safety: The lamp gets hot: do not touch the bulb or shade, and keep paper at least 20 cm from it. Keep water away from the lamp's plug and cable, and switch off at the socket before moving it. Use lab thermometers carefully.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Melting sea ice is the main cause of sea-level rise. | Sea-level rise comes mainly from land ice melting and seawater expanding as it warms. |
| The Arctic and Antarctic are changing in the same way. | Arctic sea ice has clearly declined; Antarctic sea ice varies greatly with little overall trend so far. |
| Antarctica is snowy, so it must get a lot of precipitation. | It is a polar desert: its snowfall equals only about 150 mm of rain a year. |
Worksheet answers
- White: ΔT = 3.5 °C, rate = 0.175 °C/min, Q = 100 × 4.18 × 3.5 ≈ 1,460 J. Black: ΔT = 9.0 °C, rate = 0.45 °C/min, Q = 100 × 4.18 × 9.0 ≈ 3,760 J.
- Antarctica: 150 ÷ 0.4 = 375 Gt per mm; Greenland: 270 ÷ 0.8 ≈ 338 Gt per mm. The input figures are rounded averages with their own uncertainties, so the ratios differ; the true value lies in between (roughly 340–380 Gt per mm).
- Warming → sea ice melts → dark ocean exposed (lower albedo) → more sunlight absorbed → more warming → more melting. It is positive because the result strengthens the original change.
- Antarctic sea ice changes a lot from year to year (record high in 2014, record lows in 2023), so a short satellite record makes a clear long-term trend hard to separate from natural variability.
Quiz answers
- A surface with an albedo of 0 would… absorb all the solar energy that hits it. 0 is a perfect absorber; 1 reflects everything.[11]
- Melting sea ice exposes dark water, which absorbs more energy and melts more ice. This is… a positive feedback. The change makes itself bigger.[2][7]
- If the whole Antarctic ice sheet melted, sea level would rise by about… 60 m. Greenland's ice would add about 7.4 m more.[6]
- Antarctica lost about 150 Gt of ice a year, giving about 0.4 mm of sea-level rise a year. About how many gigatons raise sea level by 1 mm? About 375 Gt. 150 ÷ 0.4 = 375.[6]
- According to NSIDC, global sea-level rise comes mainly from… meltwater from glaciers and ice sheets, and warming seawater expanding. Sea ice already floats in the ocean.[6]
- The Arctic summer minimum fell by 13.4% of the 1981–2010 average per decade. Over four decades, that is roughly… about 54% of that average. 4 × 13.4% ≈ 54% (a straight-line estimate).[2]
Going further
Download monthly sea ice extent data from NSIDC for one pole, plot September (Arctic) or February (Antarctic) values since 1979, fit a trend line and compare its slope with NSIDC's published figure.
Sources used in this lesson
- [1] How does Antarctic sea ice differ from Arctic sea ice? (National Snow and Ice Data Center (University of Colorado Boulder)): reliability High
- [2] Why sea ice matters (National Snow and Ice Data Center (University of Colorado Boulder)): reliability High
- [3] Science of Arctic weather and climate (National Snow and Ice Data Center (University of Colorado Boulder)): reliability High
- [4] Arctic Circle (Encyclopaedia Britannica): reliability High
- [5] Antarctic factsheet and geographical statistics (British Antarctic Survey (UK Government Web Archive copy)): reliability High
- [6] Why ice sheets matter (National Snow and Ice Data Center (University of Colorado Boulder)): reliability High
- [7] Sea ice (NASA Earth Observatory): reliability High
- [8] Polar bear (OLogy card) (American Museum of Natural History): reliability High
- [9] From penguins to polar bears (Woods Hole Oceanographic Institution (Oceanus magazine)): reliability High
- [10] Penguin huddle makes waves (Australian Antarctic Division (Australian Government)): reliability High
- [11] Albedo (Cryosphere glossary) (National Snow and Ice Data Center (University of Colorado Boulder)): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/polar-regions/sources/
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