Energy Flow and Climate Change: a full term of science

Ten ready-to-teach lessons for Year 10 Earth and space sciences. Print this pack and the term is prepared: every lesson comes with a step-by-step plan, the questions to ask, a student worksheet, cut-out cards, a class sheet or exit tickets, an assessment kit and worked answers.

Start here: five minutes to Monday

1. Skim the term at a glance on the next page.
2. Print the lesson you need. Each lesson is three A4 sheets: plan, worksheet, and cards, a class sheet or tickets.
3. Gather the few items under “You need” on the plan. Most come from the classroom or the science prep room.
4. Open the free interactive unit on your board or projector. Every plan tells you which picture to show and when.
5. Teach straight from the plan. Timings, talk prompts, misconceptions and worked answers are all on the one page.

For any Year 10 science teacher

The pack suits an Earth science specialist and a teacher working outside their own subject alike: each plan explains the idea in plain words, lists the misconceptions students bring, and gives worked answers. The big idea of the term: Earth’s climate is set by an energy budget. Sunlight comes in, the surface warms and gives off infrared, and greenhouse gases send part of that infrared back down. Energy and carbon move between the atmosphere, hydrosphere, biosphere and geosphere. Adding carbon from the geosphere to the atmosphere, by burning fossil fuels, strengthens the greenhouse effect, and the oceans, the ice and the living world respond in ways that can add to the change or slow it.

Two ways to run each lesson

Every lesson works as one 60-minute block, or as two 30-minute sessions; the split point is marked in every plan. Look ahead: Lessons 1, 3 and 5 each need a lamp with an ordinary bulb and two thermometers per group, and Lesson 3 needs two clear jars with lids.

Safety and care in one look

Lamp bulbs and shades get hot: set them up before the lesson and keep hands, paper and hair away. Wear safety glasses when mixing bicarbonate of soda and vinegar, and mop spills. Heated sand can stay hot for a while. Climate change can worry some students; the plans keep to the evidence and end each lesson with what people can do.

The term at a glance

One lesson a week for a term. Each lesson stands on the ones before it, so run them in order where you can.

How the sequence builds

Lessons 1 to 3 build the energy flow model: the budget of sunlight in and infrared out, how much a surface reflects, and the greenhouse effect. Lessons 4 and 5 follow carbon and heat between the four spheres. Lessons 6 and 7 read the records of carbon dioxide and temperature, separating a trend from year-to-year ups and downs. Lessons 8 and 9 add feedbacks and the evidence for the cause of the warming, and Lesson 10 brings it together.

Curriculum links (Australian Curriculum V9)

The whole term teaches the Science Understanding descriptor AC9S10U04 quoted on the cover. The lessons also work these Science Inquiry and Human Endeavour descriptors:

Assessment in this pack

• Every plan ends with “Answers and look-fors”: what meeting the idea sounds like in a Year 10 voice, with working.
• The assessment sheet near the front has a class observation checklist and a three-level rubric.
• Lesson 10 is the summative pair: the town climate task, plus the “Show what we know” check.

Materials for the whole term

One gathering session covers all ten lessons, and most of it is already in the science prep room. Two things are worth doing ahead: collect two clean steel cans for each group and paint one of each pair matt black, and check that the lamps take ordinary bulbs that give off heat.

The one-trip list

• From the prep room: lamps, thermometers, timers, clear jars with lids, small containers and safety glasses.
• From the supermarket: bicarbonate of soda, vinegar and a bag of dry sand (or sand from the playground, dried).
• From home or the canteen: empty steel cans, matt black paint or black paper, and foil.

Safety and care in one look

• Lamp bulbs and shades get hot: keep hands, paper and hair away, and switch off before moving a lamp.
• Wear safety glasses when mixing bicarbonate of soda and vinegar; mop spills at once.
• Climate change can worry some students: keep to the evidence, and end with what people are doing and can do.

Assessment without extra work

The term assesses itself. Every lesson plan ends with worked answers and look-fors, and Lesson 10 is the summative pair: the town climate task, in which students explain a coastal town’s records of temperature, hot days and sea level with the energy flow model, and the final check. This sheet is the place to note what you see along the way.

The three levels

Class observation checklist

A tick a lesson is plenty; the Lesson 10 task and check fill the gaps.

Word wall cards

Cut out the cards and build the wall as the words arrive: energy budget and infrared in Lesson 1; albedo in Lesson 2; greenhouse gas and greenhouse effect in Lesson 3; the four spheres, carbon source and carbon sink in Lesson 4; specific heat capacity in Lesson 5; parts per million and fossil fuel in Lesson 6; weather, climate and trend in Lesson 7; enhanced greenhouse effect, positive feedback and negative feedback in Lesson 8.

Dear families

This term in science, Year 10 studies how energy flows through Earth’s systems and how that explains the patterns of climate change: the balance of sunlight in and heat out, the greenhouse effect, and how carbon and heat move between the air, the oceans, living things and the rocks.

Along the way your student will warm a black can and a shiny can under a lamp, test a jar model of the greenhouse effect, compare how sand and water heat up, graph sixty years of carbon dioxide measurements, find the trend in thirty years of temperatures, and explain a coastal town’s climate record.

Try this at home

• On a sunny day, touch a dark car and a light car parked side by side (carefully). Which is hotter, and why?
• At the beach or a pool, notice that the sand or paving heats up much faster than the water.
• Look up your town’s average temperature on the Bureau of Meteorology website, and how it has changed.
• Talk about one change your household could make to use less energy.

What to ask your scientist

• What is the difference between weather and climate?
• How does the greenhouse effect work, and why do we need some of it?
• Where has most of the extra heat from global warming gone?
• How do scientists know that people are causing the recent warming?

A small note on care: climate change can be a worrying topic. The lessons keep to the evidence and spend time on what people are doing about it. Lamps used in three lessons get hot, and students are shown how to use them safely.

Warm regards,

The Year 10 science team

Printed from the free seegongsik Energy Flow and Climate Change teaching pack · seegongsik.com/au/y10/earth-and-space/AC9S10U04/pack

Earth’s energy budget

Almost all the energy that drives Earth’s climate arrives as sunlight. The surface absorbs part of it, warms up, and gives energy off as infrared. When the energy going out matches the energy coming in, the temperature holds steady: the budget balances. If less escapes, the surface warms until it gives off enough to balance again, at a higher temperature. Students model the budget with two cans of water under a lamp. The matt black can absorbs more of the light and warms faster, and both warm more slowly as they near a balance, because a warmer can gives off more energy.

We are learning to

• describe Earth’s energy budget: sunlight in and infrared out,
• explain why a warming object settles at a steady temperature,
• plan a fair test and graph its results.

Success criteria

• I can explain why the black can warmed faster than the shiny one.
• I can explain why both cans warmed more slowly as time went on.

You need

• for each group: two steel cans of the same size, one matt black and one shiny, each with 200 mL of water and a foil lid with a thermometer through it; a lamp with an ordinary bulb, the same distance from both cans; a timer,
• the worksheet (next sheet), one per student, and the class results sheet (third sheet), on the board or a bench.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the shirts, the board and the cans in Session A, and Parts C and D in Session B.

Watch for these ideas

• “Black things attract heat.” Dark surfaces absorb more of the light that falls on them; nothing is attracted.
• “Trapped heat builds up forever.” A warming object gives off more energy as it warms, until out balances in again.
• “Global warming means the Sun is getting stronger.” The Sun’s output has been steady; what has changed is how much escapes.

Make it easier, make it bigger

• Easier: plot the first three points of each line together on the board.
• Bigger: put a clear plastic cover over the black can. Predict the effect on its temperature, then test it.

Answers and look-fors

• Part B: results vary; the black can should warm clearly faster in every group.
• Part C: two curves rising from 22 °C and bending over, the black one far steeper.
• Part D: 1. The black can: it rose 12 °C against 5.1 °C for the shiny can, so it absorbed more of the lamp’s energy. 2. It rose 2.6 °C in the first 2 minutes and 1.4 °C in the last 2: as it warmed it gave off more energy, so less was left to warm it further. 3. It would level off at a steady temperature, where the energy given off matches the energy absorbed. 4. Like: energy comes in as light and leaves as infrared, and the temperature settles where they balance. Not like: Earth has an atmosphere, oceans and ice, and spins, so the sunlight falls on it unevenly.
• Bigger: the cover cuts the heat carried away by air, so the can settles at a higher temperature: a glasshouse, not the greenhouse effect.

Earth’s energy budget

A. Predict

B. Our two cans

C. An example class

Readings every 2 minutes from 0 to 12. These are example readings. Plot both cans on the same axes and join each set of points smoothly.

D. Questions

Class results: the rise in 12 minutes

Each group adds the rise of each can (final temperature minus starting temperature). Then find the class mean for each can.

If one group’s rise is very different from the rest, check the lamp distance before deciding it is an anomaly.

Reflect or absorb

Averaged over day and night and the whole globe, about 340 W of sunlight reaches each square metre at the top of the atmosphere. Not all of it is absorbed: the share a surface reflects is its albedo, from 0 for none to 1 for all. Fresh snow reflects most of the light that reaches it; the open ocean reflects very little. Earth as a whole reflects about 30%. Albedo makes a loop: when the climate warms, sea ice melts and uncovers dark ocean, which absorbs more sunlight and warms the climate further. Students work out the sunlight six surfaces absorb and complete the loop.

We are learning to

• explain albedo and how it changes the energy a surface absorbs,
• calculate the energy absorbed from the albedo,
• explain the ice and albedo loop as a feedback.

Success criteria

• I can work out how much of the incoming sunlight a surface absorbs.
• I can explain why melting sea ice adds to warming.

You need

• the worksheet (next sheet), one per student; calculators,
• the exit tickets (third sheet), cut into four.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the skiers, the board and Part A in Session A, and Parts B and C and the ticket in Session B.

Watch for these ideas

• “Ice reflects heat.” Ice reflects sunlight; it is the light that is turned away before it can warm anything.
• “Albedo is a temperature.” It is a fraction of the light reflected, with no units.
• “Melting ice warms the Earth.” The melting itself takes energy; the darker surface it uncovers is what absorbs more.

Make it easier, make it bigger

• Easier: give the share absorbed column (1 − albedo) filled in.
• Bigger: some cities paint roofs white. Use the table to explain how that could cool a city, and name one drawback.

Answers and look-fors

• Part A: fresh snow 0.15, 51 W; sea ice 0.40, 136 W; desert sand 0.65, 221 W; grassland 0.75, 255 W; forest 0.88, 299 W; open ocean 0.94, 320 W.
• Part B: the air and sea warm; sea ice melts; darker ocean is uncovered; the ocean absorbs more sunlight; and round again.
• Part C: 1. Most: open ocean; least: fresh snow. 2. (1 − 0.3) × 340 ≈ 238 W. 3. The change caused by warming leads to more warming: a positive feedback. 4. Dark roads and roofs absorb more sunlight than grass and trees, and there are fewer plants to cool the air.
• Exit ticket: 1. The share of sunlight a surface reflects. 2. Fresh snow. 3. (1 − 0.06) × 340 ≈ 320 W.
• Bigger: a white roof reflects most sunlight, so less is absorbed; a drawback is glare, or needing more heating in winter.

Reflect or absorb

A. Six surfaces

Each square metre receives 340 W of sunlight on average. Share absorbed = 1 − albedo. Energy absorbed = share absorbed × 340.

B. The ice and albedo loop

Complete the loop: what happens next at each step?

C. Questions

Exit tickets

The greenhouse effect

Greenhouse gases, such as carbon dioxide, methane and water vapour, let sunlight through but absorb infrared from the warm surface and send part of it back down. Without them Earth’s surface would average about −18 °C instead of about 15 °C. A common classroom model puts two sealed jars under a lamp, one with extra carbon dioxide. Its results are small and messy, which makes it a good lesson in judging a model: a closed jar warms mostly because the lid stops warm air rising away, a few centimetres of gas are nothing like kilometres of atmosphere, and the carbon dioxide jar starts cooler because the reaction that makes the gas takes in heat. Students run the test, then decide what it can and cannot show.

We are learning to

• explain how greenhouse gases keep Earth’s surface warm,
• compare a difference in results with the uncertainty of the measurements,
• judge how well a model represents the real thing.

Success criteria

• I can explain the greenhouse effect with sunlight in, infrared out and some sent back down.
• I can name two ways the jar model differs from Earth’s atmosphere, and one way to improve the test.

You need

• for each group: two clear jars with lids and a thermometer through each lid; a lamp the same distance from both; a teaspoon of bicarbonate of soda and a little vinegar in a small cup to make carbon dioxide in one jar; safety glasses,
• the worksheet (next sheet), one per student, and the class results sheet (third sheet), on the board or a bench.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the night, the board and the jars in Session A, and Part B in Session B.

Watch for these ideas

• “The greenhouse effect is bad.” Without it Earth would freeze; the problem is strengthening it.
• “Greenhouse gases trap heat like a lid.” They absorb infrared and send some back down; a glasshouse works by stopping warm air leaving.
• “The ozone hole causes global warming.” They are separate problems; ozone loss lets in more ultraviolet.

Make it easier, make it bigger

• Easier: work out the two rises in the example class together before the questions.
• Bigger: design a better test of whether carbon dioxide absorbs infrared, using equipment a university or industry lab might have.

Answers and look-fors

• Part A: results vary; the jars often end within a degree or two of each other, and sometimes the carbon dioxide jar is not warmer.
• Part B: 1. 0.9 °C; each thermometer is ±0.5 °C, so a difference this small could be partly uncertainty. 2. The air jar rose 9.5 °C and the carbon dioxide jar 10.8 °C; comparing rises allows for the cooler start. 3. Any two: the lid stops warm air leaving, which is not how the greenhouse effect works; a few centimetres of gas, not kilometres; the jar has far more carbon dioxide than air does; the reaction leaves moisture and vinegar vapour. 4. Repeat several times and swap the jars round; start at the same temperature; use more precise thermometers; leave the lids off or use thin film.
• Look for students who treat a difference of about a degree with caution rather than as proof.
• Bigger: shine infrared through a long tube of carbon dioxide and of air, and measure how much gets through with an infrared sensor.

The greenhouse effect

A. Our two jars

Safety glasses on while the bicarbonate of soda and vinegar fizz. The lamp gets hot: keep hands away.

B. Judge the model

An example class’s readings, every 3 minutes. Each thermometer reads to ±0.5 °C.

Class results: two jars

Each group adds how much each jar rose in 15 minutes. Then find the class mean, and count the groups whose carbon dioxide jar rose more.

A model can be useful even when its results are small; the class pattern matters more than any one jar.

Carbon on the move

Carbon and energy move all the time between the four spheres: the atmosphere, the hydrosphere, the biosphere and the geosphere. Plants and the oceans take carbon dioxide out of the air; breathing, rotting, fires and volcanoes put it back. Over millions of years, carbon from living things was buried and locked into the geosphere as coal, oil and gas. Burning those fuels moves that old carbon into the atmosphere far faster than any natural flow takes it out, and that is the main reason the level of carbon dioxide is rising. Students sort twelve flows into sources, sinks and flows of heat, and name the spheres involved.

We are learning to

• describe flows of carbon and energy between the four spheres,
• tell carbon sources from carbon sinks,
• explain why burning fossil fuels changes the carbon balance.

Success criteria

• I can sort flows into sources, sinks and flows of heat, and name the spheres each one links.
• I can explain why burning coal adds to the carbon in the air in a way that breathing does not.

You need

• the carbon cards (third sheet), one set per pair, with scissors,
• the worksheet (next sheet), one per student.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the coal, the board and the sort in Session A, and Parts B and C in Session B.

Watch for these ideas

• “Plants make oxygen, so they remove all our carbon dioxide.” Sinks take up only about half of what we add each year.
• “Breathing is as bad as burning coal.” Breathing returns carbon that plants took in recently; coal adds carbon locked away for millions of years.
• “Carbon dioxide is a pollutant only humans make.” It is a natural part of the air; the problem is adding more, faster than sinks remove it.

Make it easier, make it bigger

• Easier: label four corners of the desk with the four spheres and move each card from one corner to another before sorting.
• Bigger: mangroves and seagrass store carbon fast and keep it for centuries. Why might protecting them be called “blue carbon”?

Answers and look-fors

• Part A: adds co₂ to the air C, E, H, J, L; takes co₂ out of the air A, F, G, K; moves heat, not carbon B, D, I.
• Part B: C geosphere to atmosphere; A atmosphere to biosphere; F atmosphere to hydrosphere; D hydrosphere to atmosphere; H biosphere to atmosphere; K hydrosphere to geosphere.
• Part C: 1. Burning coal and the volcano: carbon from the geosphere. 2. Breathing returns carbon that plants took from the air in the last year or two; coal adds carbon that was out of the cycle for millions of years, so the total in the air and oceans grows. 3. Any two: plant and protect forests; restore mangroves, seagrass and saltmarsh; improve soils; protect the oceans.
• Bigger: they are sinks in coastal and ocean waters, the hydrosphere’s edge, storing carbon in mud for a long time.

Carbon on the move

A. Sort the carbon cards

B. Which spheres?

For each card, name the sphere the carbon or heat comes from, and the sphere it goes to.

C. Questions

Sources, sinks and heat

Cut out the three headings and the twelve cards. Sort each card under the heading that describes what moves.

Teacher note: the answer letters are in the plan. The three piles are different sizes.

The ocean’s part

Water takes far more energy to warm than rock or sand: its specific heat capacity is about 4 200 J for each kilogram and degree, against about 830 J for sand. The ocean is also deep and always mixing, so it soaks up energy and releases it slowly. More than 90% of the extra energy kept in by greenhouse gases has gone into the oceans. That slows the warming of the air, but warmer water expands and raises sea level, and marine heatwaves have bleached the Great Barrier Reef several times since 2016. Students warm sand and water under a lamp, let them cool, and explain the ocean’s part in the climate.

We are learning to

• compare how sand and water warm and cool,
• explain specific heat capacity,
• explain the ocean’s part in storing and moving energy.

Success criteria

• I can use my results to explain why water warms and cools more slowly than sand.
• I can explain why coastal places have milder climates than inland ones.

You need

• for each group: 200 g of dry sand and 200 g of water at room temperature in two matching containers, two thermometers, a lamp the same distance from both, and a timer,
• the worksheet (next sheet), one per student, and the exit tickets (third sheet), cut into four.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the beach, the board and the readings in Session A, and Parts B and C and the ticket in Session B.

Watch for these ideas

• “The water was colder because it reflected the light.” Both absorb; water needs far more energy for each degree, and mixes it deeper.
• “The ocean absorbing heat solves the problem.” It delays warming of the air but raises sea level and harms reefs and fisheries.
• “Heat and temperature are the same.” The same energy gives a smaller temperature rise in water than in sand.

Make it easier, make it bigger

• Easier: give the axes with both lines started, and ask students to finish them.
• Bigger: warm water expands. If the top 700 m of the ocean warmed by 0.5 °C, would sea level rise? What else makes it rise?

Answers and look-fors

• Part A: results vary; the sand should warm and cool much faster in every group.
• Part B: the sand rose 12 °C in 10 minutes and fell 9 °C in the next 10; the water rose 3.1 °C and fell 1.2 °C.
• Part C: 1. The sand. 2. Water needs about 4 200 J to warm each kilogram by 1 °C and sand about 830 J, so the same energy warms water about 5 times less. 3. The sea warms slowly in summer and cools slowly in winter, keeping the coast milder. 4. It slows the warming of the air now, but the stored energy expands the water, raises sea level, causes marine heatwaves, and keeps warming the climate for a long time.
• Exit ticket: 1. Water. 2. The energy needed to warm 1 kg of it by 1 °C. 3. The oceans.
• Bigger: yes, a little, because warmer water takes up more room; melting ice on land adds more water too.

The ocean’s part

A. Our sand and water

Lamp on for 10 minutes, then off for 10 minutes. The lamp stays hot after it is switched off.

B. An example class

Readings every 2 minutes from 0 to 20, with the lamp off after 10 minutes. These are example readings. Plot both lines.

C. Questions

Exit tickets

The carbon dioxide record

In 1958 Charles David Keeling began measuring carbon dioxide on the volcano Mauna Loa in Hawaii, far from cities and forests, and the measurements have run ever since. Since 1976 the Cape Grim station in north-west Tasmania has measured some of the cleanest air on Earth, and it shows the same rise. Air bubbles trapped in Antarctic ice show that before about 1800 the level was near 280 ppm for thousands of years. Students graph sixty years of the Mauna Loa annual means, work out the rise in each decade, and see that it is not only rising but rising faster.

We are learning to

• graph a long record and describe its trend,
• calculate a rate of change and see whether it is changing,
• explain why measuring stations are placed far from cities.

Success criteria

• I can work out the rise in each decade and say whether the rise is speeding up.
• I can compare today’s level with the level before 1800.

You need

• the worksheet (next sheet), one per student, with a ruler and a calculator,
• the exit tickets (third sheet), cut into four.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the ppm, the board and the graph in Session A, and Parts B and C and the ticket in Session B.

Watch for these ideas

• “A few hundred parts per million is too little to matter.” Carbon dioxide absorbs infrared strongly; small amounts make a large difference.
• “The rise is steady.” The rise each decade has grown, from under 10 ppm to over 20 ppm.
• “The yearly wiggle shows the record is unreliable.” It is plants in the northern hemisphere taking in carbon dioxide each summer.

Make it easier, make it bigger

• Easier: give the first two points plotted, and the first decade’s rise worked.
• Bigger: if the rise stayed at the last decade’s rate, when would the level reach double the level before 1800?

Answers and look-fors

• Part A: a line that rises every decade and curves upward.
• Part B: 1960 to 1970, 8.8 ppm; 1970 to 1980, 13.1 ppm; 1980 to 1990, 15.6 ppm; 1990 to 2000, 15.3 ppm; 2000 to 2010, 20.2 ppm; 2010 to 2020, 24.3 ppm. The rise grew, apart from a small dip in the 1990s.
• Part C: 1. 414.2 − 280 = 134.2 ppm higher, about 48% more. 2. Mostly burning coal, oil and gas, and clearing forests. 3. Far from cities, traffic, factories and forests, the air is well mixed, so local sources do not swamp the measurement. 4. Plants in the northern hemisphere, where most land is, take in carbon dioxide as they grow each summer and release it as leaves rot in winter.
• Exit ticket: 1. Parts per million. 2. It is rising, and faster each decade. 3. About 280 ppm.
• Bigger: double is 560 ppm, 145.8 ppm above 2020; at 24.3 ppm a decade that takes about 60 years.

The carbon dioxide record

The yearly average level of carbon dioxide measured at Mauna Loa, Hawaii (from the US National Oceanic and Atmospheric Administration). Before about 1800 the level was near 280 ppm.

A. Graph the record

B. The rise in each decade

C. Questions

Exit tickets

Weather or climate?

Weather is the state of the air on a given day; climate is the average weather of a place over 30 years or more. A single year can be cooler than the one before, from a La Niña, a cloudy summer or a volcanic eruption, without changing the trend underneath. To find a trend, scientists average over many years. Students graph thirty years of example temperature differences from a long-term average, in the pattern of real records, mark the three decade averages, and see a clear rise through the ups and downs. Australia’s climate has warmed by about 1.5 °C since national records began in 1910.

We are learning to

• tell weather from climate,
• find a trend in noisy data by averaging,
• explain why one cool year does not disprove a warming trend.

Success criteria

• I can work out decade averages and use them to describe the trend.
• I can explain, with the data, why a cool year does not mean warming has stopped.

You need

• the worksheet (next sheet), one per student, with a calculator,
• the exit tickets (third sheet), cut into four.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the week, the board and the graph in Session A, and Parts B and C and the ticket in Session B.

Watch for these ideas

• “A cold year proves warming has stopped.” Single years vary; the trend shows in averages over decades.
• “Climate is the weather this season.” Climate is the average over 30 years or more.
• “1.5 °C is too small to matter.” Averages hide big changes in extremes: more very hot days, heavier rain, longer droughts.

Make it easier, make it bigger

• Easier: give the sum of each decade, so students only divide by 10.
• Bigger: work out a running five-year average for the last ten years. Does it rise as smoothly as the decade averages?

Answers and look-fors

• Part A: thirty points that zigzag up and down but drift upward.
• Part B: 1991 to 2000, +0.21 °C; 2001 to 2010, +0.41 °C; 2011 to 2020, +0.70 °C: each decade warmer than the last.
• Part C: 1. 14 of the 29 years after the first. 2. No: single years go up and down, but each decade average is higher; the rise from the first decade to the last is about 0.5 °C. 3. A 30-year average smooths out the year-to-year ups and downs, so a real change shows. 4. Weather: a hot day, a storm or a wet week. Climate: a place’s average summer temperature or rainfall over 30 years.
• Exit ticket: 1. Weather is day to day; climate is the average over 30 years or more. 2. No. 3. By averaging over many years.
• Bigger: the five-year averages rise more smoothly than single years, but still wobble more than decade averages.

Weather or climate?

How much warmer or cooler each year was than a long-term average, from 1991 to 2020. These are example values, in the pattern of real records.

A. Graph it

Plot each year at its place along the axis; 1991 is just after 1990. Join the points with straight lines.

B. Decade averages

Add the ten values and divide by 10. Draw each average as a flat line across its decade on the graph.

C. Questions

Exit tickets

Feedbacks

A cause, such as burning fossil fuels, tips the energy budget. What happens next depends on feedbacks: changes that the warming itself sets off. A positive feedback amplifies the warming, like the ice and albedo loop or the extra water vapour that warmer air holds. A negative feedback dampens it: the most important is that a warmer surface gives off more infrared. Scientists find that, overall, the amplifying feedbacks win, which is why the climate is more sensitive to carbon dioxide than the greenhouse gas alone would make it. Students sort twelve changes into feedbacks that amplify, feedbacks that dampen, and causes, and draw one loop.

We are learning to

• tell a cause of climate change from a feedback,
• tell feedbacks that amplify warming from those that dampen it,
• draw a feedback loop and explain it.

Success criteria

• I can sort changes into amplifying feedbacks, dampening feedbacks and causes, and explain one of each.
• I can draw a feedback loop with arrows and say whether it amplifies or dampens.

You need

• the feedback cards (third sheet), one set per pair, with scissors,
• the worksheet (next sheet), one per student.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the microphone, the board and the sort in Session A, and Parts B and C in Session B.

Watch for these ideas

• “Positive feedback is good.” Positive means it adds to the change, here more warming; negative means it works against it.
• “Everything that adds carbon dioxide is a feedback.” Only changes caused by the warming are feedbacks; burning fuel is a cause.
• “Feedbacks will cancel out.” Scientists find the amplifying feedbacks are stronger overall.

Make it easier, make it bigger

• Easier: sort the causes out first, by asking of each card “does warming make this happen?”.
• Bigger: a tipping point is a change that keeps going even if the cause stops. Which card could become one, and why?

Answers and look-fors

• Part A: amplifies warming B, C, F, H, K; dampens warming A, D, J; a cause, not a feedback E, G, I, L.
• Part B: for example, warmer air holds more water vapour, which absorbs more infrared, which warms the air more: amplifies.
• Part C: 1. A cause changes the energy budget in the first place; a feedback is a change the warming itself sets off. 2. It amplifies: the warming leads to more warming. 3. The amplifying feedbacks add to the warming from carbon dioxide, so the same amount of extra gas gives more warming.
• Bigger: thawing frozen ground or melting ice sheets: once started they can keep releasing gas or losing ice for centuries.

Feedbacks

A. Sort the feedback cards

B. Draw a loop

Choose one amplifying feedback. Draw it as a loop of boxes and arrows that starts and ends with “the climate warms”.

C. Questions

Amplify, dampen, or cause?

Cut out the three headings and the twelve cards. Sort each change under the heading that describes it.

Teacher note: the answer letters are in the plan. The three piles are different sizes.

What is causing it?

The climate has changed before, for natural reasons: changes in Earth’s orbit, in the Sun, and volcanic eruptions. So how do scientists know the recent warming is caused by people? Like detectives, they look for fingerprints that only one cause would leave. A brighter Sun would warm the whole atmosphere and warm days more than nights; extra greenhouse gas warms the lower atmosphere while the upper atmosphere cools, and warms nights more than days. The carbon added to the air carries the chemical signature of fossil fuels. Students match six observations with what each one shows, then build an argument from them.

We are learning to

• use several kinds of evidence to judge a cause,
• explain how a fingerprint can rule a cause in or out,
• write an argument that connects claim, evidence and reasoning.

Success criteria

• I can match each observation with what it shows about the cause of the warming.
• I can explain why a brighter Sun cannot explain the recent warming.

You need

• the clue cards (third sheet), one set per pair, with scissors,
• the worksheet (next sheet), one per student.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the suspects, the board and the matching in Session A, and Parts B and C in Session B.

Watch for these ideas

• “The climate has always changed, so this is natural.” Past changes had causes too; the fingerprints point to greenhouse gases now.
• “Correlation proves cause.” The case rests on several fingerprints, and on physics that predicts them, not on one pattern.
• “Scientists disagree about the cause.” The scientific assessments agree that people have caused the recent warming.

Make it easier, make it bigger

• Easier: give the first pair, and ask students to find the others by asking “what would cause this?”.
• Bigger: write the one observation that would most change your mind, and explain why.

Answers and look-fors

• Part A: G with A, D with J, E with L, B with H, K with F, I with C.
• Part B: a strong argument names the claim (people are causing the recent warming), uses at least two clues, such as the fossil carbon signature and the cooling upper atmosphere, and explains how each points to greenhouse gases and away from the Sun.
• Part C: 1. The Sun’s output has not risen since the 1980s, and a brighter Sun would warm the upper atmosphere and the days more, not less. 2. The extra energy is not escaping to space, and most of it is going into the oceans. 3. Physics predicts each fingerprint in advance, and several separate kinds of measurement agree.
• Bigger: answers vary; for example, the upper atmosphere warming along with the lower, which would point to the Sun.

What is causing it?

A. Match the clues

Pair each observation card with the card that says what it shows. Write the pairs of letters.

B. Make the case

Write an argument: a claim, at least two pieces of evidence from the cards, and the reasoning that links each to the claim.

C. Questions

Observations and what they show

Cut out the twelve cards. Six are observations; six say what an observation shows. Match each pair.

Teacher note: the pairs are in the plan. Every card has exactly one partner.

Show what we know

The term comes together. In the task, students read a coastal Australian town’s records over sixty years: the average temperature, the number of very hot days, and the sea level at the town’s tide gauge. They describe each trend, explain it with the energy flow model, from the extra greenhouse gas to the oceans and the ice, and judge a resident’s claim. Then they sit the eight-question final check, and the class plays the unit quiz as a game on the board.

We are learning to

• describe trends in climate records,
• explain the trends with energy flow between the four spheres,
• use evidence to answer a claim.

Success criteria

• I can explain each of the town’s three trends using the energy flow model.
• I can answer the final check on my own.

You need

• the task (next sheet) and the final check (third sheet), one each per student,
• the interactive unit open on the board for the quiz; mini whiteboards if you have them.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the model and the task in Session A, and the final check and the quiz in Session B.

Watch for these ideas

• Students who explain the sea level rise only by melting sea ice: floating ice melting adds almost nothing; warming water and land ice do.
• Students who answer the resident from one cool summer: return to the decade averages of Lesson 7.
• Students who describe the trends without explaining them: ask where the energy came from and where it went.

Make it easier, make it bigger

• Easier: give sentence starters for each explanation: “Extra greenhouse gas means…”.
• Bigger: suggest two changes the town could make to cope with these trends, and one to slow them.

Answers and look-fors

• Task: 1. The average rose 1.1 °C, very hot days rose from 2.1 to 5.6 a year, and the sea rose 105 mm, each faster in recent decades. 2. Extra greenhouse gas sends more infrared back down, so the surface warms until the budget balances again. 3. A small rise in the average shifts the whole range of temperatures up, so days above 35 °C become far more common. 4. Most of the extra energy goes into the ocean: the warmer water expands, and melting ice on land adds water. 5. No: one summer is weather; the decade records all rise.
• Final check: 1. infrared. 2. Sunlight in, infrared out; greenhouse gases send some infrared back down; the surface settles warmer. 3. It absorbs more: (1 − 0.06) × 340 ≈ 320 W against (1 − 0.85) × 340 ≈ 51 W. 4. fresh snow. 5. Burning fossil fuels moves carbon from the geosphere to the atmosphere. 6. the oceans. 7. Weather is day to day; climate is the average over 30 years or more. 8. Warming melts sea ice, uncovering darker ocean that absorbs more sunlight, which causes more warming: an amplifying feedback.
• Mark the task against the rubric in the assessment kit; the check covers the budget, the greenhouse effect, the spheres and feedbacks.

A town’s climate record

Records for a coastal town in Australia. These are example values, in the pattern of real records. Sea level is measured at the town’s tide gauge, from the average of the 1960s.

Show what we know