HS-ESS2-4NGSS*ScienceEarth and Space ScienceGrades 9-12
HS-ESS2-4: Modeling Energy Flow and Changes in Climate
In plain English: HS-ESS2-4 is the NGSS high school performance expectation that asks students to use a model of energy flowing into and out of Earth systems to describe how changes in that flow change climate. Causes act on very different timescales, from a volcanic eruption over a few years to shifts in Earth's orbit over tens of thousands of years. It is usually taught in Earth and Space Science.
Use a model to describe how variations in the flow of energy into and out of Earth systems result in changes in climate.
Clarification Statement: Examples of the causes of climate change differ by timescale, over 1-10 years: large volcanic eruption, ocean circulation; 10-100s of years: changes in human activity, ocean circulation, solar output; 10-100s of thousands of years: changes to Earth's orbit and the orientation of its axis; and 10-100s of millions of years: long-term changes in atmospheric composition.
Assessment Boundary: Assessment of the results of changes in climate is limited to changes in surface temperatures, precipitation patterns, glacial ice volumes, sea levels, and biosphere distribution.
Next Generation Science Standards · Disciplinary Core Idea: Earth's Systems · Official standard
Students use an energy budget model of Earth: sunlight comes in, part of it is reflected, and the rest is absorbed and later sent back to space as infrared. When the energy coming in equals the energy going out, the average temperature holds steady. When a cause tips that balance, the Earth system gains or loses energy until a new balance is reached, and the climate changes. Students calculate the flows, change one arrow of the model at a time, sort real causes by their timescale, and predict what the change does to the climate.
The NGSS Clarification Statement says: "Examples of the causes of climate change differ by timescale, over 1-10 years: large volcanic eruption, ocean circulation; 10-100s of years: changes in human activity, ocean circulation, solar output; 10-100s of thousands of years: changes to Earth's orbit and the orientation of its axis; and 10-100s of millions of years: long-term changes in atmospheric composition." The Assessment Boundary says: "Assessment of the results of changes in climate is limited to changes in surface temperatures, precipitation patterns, glacial ice volumes, sea levels, and biosphere distribution." So every result on this page is one of those five: surface temperature, precipitation patterns, glacial ice volume, sea level or where living things are found. The page uses a solar constant of 1361 W/m², the Stefan-Boltzmann constant σ = 5.67 × 10-8 W/(m²·K4) and an average albedo of 0.30. All data sets are invented for teaching or are rounded values, and they are labeled that way. Students do the practice of using a model: they calculate with it, test it against data, change its inputs and name its limits.
Learning Objectives
By the end of this lesson, students will be able to:
Use an energy budget model (sunlight in, sunlight reflected, infrared out) to explain why Earth's average temperature holds steady when the flows balance
Calculate how a change in albedo, solar output or the greenhouse effect changes the energy absorbed or emitted and the balance temperature
Sort causes of climate change by timescale, from 1-10 years to hundreds of millions of years, and name the energy flow each cause changes
Predict the results of an energy imbalance for surface temperature, precipitation patterns, glacial ice volume, sea level and the distribution of living things
Critique a climate model by naming what it includes, what it leaves out and how that limits its predictions
Prior Knowledge Required
Students should already be comfortable with:
How unequal heating and Earth's rotation drive atmospheric and ocean circulation MS-ESS2-6
Evidence for the rise in global temperatures over the past century MS-ESS3-5
Energy transfer by radiation, and the idea that a warmer object gives off more energy
Scientific notation and calculator work with powers and roots 8.EE.A.4
Show a photo of a parked car in the sun, or describe it, and give students two minutes to write.
Warm-Up Prompt
"A car parked in the sun heats up quickly, but after about an hour its inside temperature stops rising, even though the sun keeps shining. Why does it level off? Name two changes that would make it level off at a higher temperature."
Collect answers. Steer the class to the idea that the car gives off more energy as it warms, and that it stops warming once energy out equals energy in. Changes students suggest (a darker car, closed windows, stronger sunlight) map onto the three arrows of the model used today.
Direct Instruction15-20 minutes
The energy budget model. Draw Diagram 1. Three flows set Earth's average temperature: sunlight in, sunlight reflected (set by the albedo, the reflected fraction) and infrared emitted. A warmer object emits more: the Stefan-Boltzmann law gives the emitted power per square meter as σT4. If absorbed energy is larger than emitted energy, Earth's systems gain energy and warm until emission catches up. Every cause of climate change works by changing one of the arrows. Work through the examples, and after each one ask which arrow changed and in which direction.
Earth's balanced energy budget
Sunlight arrives at 1361 W/m² facing the Sun. Spread over the whole sphere, the average is 1361 ÷ 4 ≈ 340 W/m². Earth reflects 30% (albedo 0.30).
Result: Reflected ≈ 102 W/m², absorbed ≈ 238 W/m². Setting σT4 = 238 gives T ≈ 255 K (-18 °C). The measured average surface temperature is about 288 K (15 °C): the 33 K difference is the warming from greenhouse gases.
Large volcanic eruption (1-10 years)
Sulfate haze from a large eruption raises Earth's albedo from 0.300 to 0.305 for about two years.
Result: Absorbed sunlight falls from 238.2 to 236.5 W/m², a loss of 1.7 W/m². The balance temperature drops by about 0.46 K, so the surface cools for a year or two, then recovers as the haze settles out.
Solar output (10-100s of years)
Over one 11-year sunspot cycle the solar constant rises and falls by about 1.3 W/m² (about 0.1%).
Result: Change in absorbed energy = 1.3 ÷ 4 × 0.70 ≈ 0.23 W/m², and the balance temperature changes by only about 0.06 K: a small, repeating nudge.
Human greenhouse gases (10-100s of years)
At 288 K the surface emits σT4 ≈ 390 W/m², but only 238 W/m² escapes to space, a fraction ε ≈ 0.611. Suppose added greenhouse gases lower ε to 0.604.
Result: At 288 K the outgoing flow drops to 235.6 W/m², so Earth gains about 2.6 W/m². The surface warms until ε σT4 = 238.2 again, at about 288.8 K. This simple model has no feedbacks, so the real warming would be larger.
Tilt of the axis (10-100s of thousands of years)
The tilt of Earth's axis swings between about 22.1° and 24.5° over roughly 41,000 years. At 65°N the noon Sun on the June solstice stands 90° - 65° + tilt above the horizon.
Result: Sun height 47.1° at low tilt and 49.5° at high tilt. Noon sunlight on level ground scales with sin(height): 0.760 ÷ 0.733 ≈ 1.04, about 4% stronger. Warmer summers melt more of the winter snow, so ice sheets shrink and sea level rises.
Then show Diagram 2. Stress that the same model covers causes that act over a few years and causes that act over hundreds of millions of years. Ask students to compare the size of each change in W/m² with how long it lasts. Ocean circulation appears twice in the Clarification Statement: an El Niño moves heat between subsurface ocean water and the surface over a year or two, and slower changes in currents move heat over decades to centuries.
Guided Practice15 minutes
Pairs complete the table below for four causes, one from each timescale in Diagram 2. The last row describes a long-term change in atmospheric composition, with rounded values.
Guided practice: causes of climate change and the energy flow they change
Cause
Timescale
Arrow that changes
Predicted result
El Niño: warm surface water spreads across the tropical Pacific
1-2 years
Heat moves from the ocean to the air (redistribution inside the system)
Warmer global surface for about a year; wetter and drier regions shift
Burning fossil fuels raises CO2 from about 280 to over 400 ppm
About 150 years so far
? (pairs fill in)
? (pairs fill in)
Earth's orbit becomes more or less oval (eccentricity)
About 100,000 and 400,000 years
? (pairs fill in)
? (pairs fill in)
Over the last 50 million years, weathering of uplifted rock and burial of carbon lowered CO2 from more than 1,000 ppm to under 300 ppm; an ice sheet formed on Antarctica about 34 million years ago
Tens of millions of years
? (pairs fill in)
? (pairs fill in)
For each row, name the arrow of Diagram 1 that changes and say whether Earth gains or loses energy until a new balance is reached.
Predict one result, using only these: surface temperature, precipitation patterns, glacial ice volume, sea level, where living things are found.
Compare the CO2 rows. Both change how much infrared escapes. What makes them different? (Rate: a century versus tens of millions of years.)
Share out. Correct answers: CO2 rows change the infrared arrow (less escapes when CO2 rises, more when it falls); eccentricity changes how sunlight is spread through the year and between hemispheres.
Independent Practice10-15 minutes
Each student uses the model on three albedo values. Keep the solar constant at 1361 W/m².
Independent practice: albedo scenarios
Scenario
Albedo
Absorbed (W/m²)
Balance temperature (K)
A: more ice and snow cover
0.32
?
?
B: present day
0.30
238.2
254.6
C: less ice and snow cover
0.28
?
?
Answers: A absorbs 231.4 W/m² and balances near 252.7 K; C absorbs 245.0 W/m² and balances near 256.4 K. Students then write two sentences: which scenario matches a glacial period, and what the model predicts for sea level in that scenario and why.
Closure5 minutes
Exit ticket: "Sketch the three arrows of the energy budget. Put a + or - on each arrow to show what a large volcanic eruption does in the first two years, and name one result you could measure." Look for a larger reflected arrow, a smaller absorbed amount and a cooler surface or a change in rainfall.
Differentiation Strategies
For Struggling Students
Give a partly filled energy budget diagram with the three arrows drawn, so students only add numbers and + or - signs
Provide the fourth-root step as a calculator routine: divide by 5.67 × 10-8, then press the square root key twice
Use a sentence frame: "This cause changes the ___ arrow. Earth gains / loses energy, so ___ until the flows balance again. One result is ___."
For Advanced Students
Add an ice-albedo feedback to the spreadsheet model: make the albedo depend on temperature and compare the warming with and without it
Estimate how many years the ocean mixed layer in the Activity 2 model needs to get halfway to its new balance, and explain what sets that time
Compare the size of the energy change from one solar cycle with the change from a large eruption, and argue which one a 30-year temperature record would show more clearly
Assessment Guidance
What to Look For
Check that students name a specific arrow and a direction for every cause, not just "it gets hotter". Look for the idea of a new balance: warming continues only while energy in exceeds energy out. Listen for the error that greenhouse gases let more sunlight in, for students who treat the fourth power as a straight proportion, and for predictions outside the five results named in the Assessment Boundary.
02
Classroom Activities
3 Activities
1
Lamp and Tilt Lab: Modeling Changes in Sun Angle
25 minGroups of 3-4
Groups model how a change in the tilt of Earth's axis changes the sunlight a surface receives. A black paper "ground" card with a thermometer taped under it faces a lamp at three angles, and groups compare the temperature rise with the cosine rule for sunlight striking at an angle.
Procedure
Tape the bulb or probe of an alcohol-filled or digital thermometer under a 10 cm × 10 cm square of black construction paper. Never use a mercury thermometer.
Clamp the lamp so the bulb is 30 cm from the center of the card. Measure the distance with a ruler for every trial.
Trial 1: the card faces the lamp squarely (0° from straight on). Trials 2 and 3: prop the card with books so the light strikes it 30° and 60° from straight on. Check the angle with a protractor.
Record the starting temperature, switch the lamp on for 5 minutes, and record the final temperature. Let the card cool to room temperature between trials.
Safety: wear goggles in case a bulb breaks. Incandescent and halogen bulbs and their shades get hot: do not touch them, keep paper at least 30 cm away, and switch off the lamp when you are not measuring. Unplug by the plug, not the cord, and keep water bottles off the lab table. Report a broken thermometer to the teacher and do not clean it up yourself.
Sample Data (invented)
Temperature rise after 5 minutes: 8.0 °C at 0°, 6.8 °C at 30°, 4.1 °C at 60°. The cosine rule predicts that the energy per square meter drops to cos 30° ≈ 0.87 and cos 60° = 0.50 of the straight-on value.
Discussion Questions
Divide each rise by the 0° rise (0.85 and 0.51). How well does the cosine rule describe the data? What could explain the small differences?
In the model, which arrow of Diagram 1 does the tilt of the card change for the patch of ground under the lamp?
When Earth's tilt increases, the noon summer Sun is higher over places near the poles. Use your data to predict what happens to summer snowmelt there and to glacial ice volume over thousands of years.
What does the lamp model leave out that the real Earth has (day length, seasons, the atmosphere)?
Modification for Distance Learning
Students analyze the sample data in a spreadsheet, plot the rise against the cosine of the angle, and post a model sketch with their prediction for high-latitude ice.
2
Spreadsheet Energy Balance Model
20 minPairs
Pairs build a one-box climate model in a spreadsheet. Each row is one year. The model computes absorbed sunlight, outgoing infrared (ε σT4), the imbalance, and the temperature change for the next year. They run a volcanic scenario and a greenhouse gas scenario.
Model Rules
Absorbed = 1361 ÷ 4 × (1 - albedo). Outgoing = ε × 5.67 × 10-8 × T4, with ε = 0.6106 so that 288 K is balanced at albedo 0.300.
Next year's T = this year's T + 0.108 × (absorbed - outgoing). The factor 0.108 K per W/m² comes from the heat capacity of the top 70 m of ocean: seconds in a year ÷ (1000 kg/m³ × 4186 J/(kg·K) × 70 m).
Start at T = 288.00 K.
Scenario Runs
Eruption: set the albedo to 0.305 in years 1 and 2, then back to 0.300.
Greenhouse gases: keep the albedo at 0.300 and lower ε to 0.604 from year 1 on. Run 20 years.
Graph T against year for both runs on one chart.
Sample Output (from these rules)
Eruption: 288.00, 287.82, 287.70, 287.80, 287.87 K in years 0-4, and back within 0.02 K of 288 K (287.98 K) by year 8. Greenhouse gases: 288.00, 288.28, 288.46, 288.57 K in years 0-3, leveling off at 288.78 K after about 11 years.
Discussion Questions
In the eruption run, the lowest temperature comes in year 2, after the haze has done its work. Why does the temperature keep falling while the albedo is high, and why does it recover slowly?
In the greenhouse run, why does warming slow down each year even though ε stays at 0.604?
Change the 70 m ocean layer to 200 m. Predict, then test, what happens to the speed of warming and to the final temperature.
Name two parts of the real climate system this box model leaves out, and say how each would change its predictions.
Challenge Variation
Add an ice-albedo feedback (beyond this standard's required model): let the albedo drop by 0.002 for every 1 K above 288 K and compare the final temperature with the run without it.
3
Climate Cause Stations Across Timescales
25 minGroups of 3-4
Four stations each show one invented or rounded data set for a cause of climate change. At each station, groups name the timescale, draw the energy budget with the changed arrow, and predict one result from the Assessment Boundary list. Groups rotate every 6 minutes.
Station Data
Station 1, eruption year (invented): global average temperature anomaly +0.30, +0.08, +0.02, +0.18, +0.27 °C in the year before and the four years after a large tropical eruption.
Station 2, a century of change (rounded): CO2 315, 340, 370, 415 ppm in 1960, 1980, 2000, 2020; solar output within about 0.1% of 1361 W/m² the whole time.
Station 3, a glacial cycle (rounded): sea level about 120 m lower than today 20,000 years ago, when ice sheets covered much of North America; ice sheets melted over the next 10,000 years as summer sunlight at high northern latitudes increased.
Station 4, deep time (rounded): CO2 more than 1,000 ppm about 50 million years ago with no large ice sheets and palm-like plants in the Arctic; below 300 ppm in recent ice ages with large ice sheets.
Discussion Questions
At Station 1, the coolest year is the second year after the eruption. How does the in-out model explain a delay?
At Station 2, solar output hardly changed while CO2 rose by 100 ppm. Which arrow of the model does the data point to, and why can the Sun not explain the trend?
At Station 3, how many meters per century did sea level rise on average while the ice melted? (120 m over 10,000 years is 1.2 m per century.)
Stations 2 and 4 both involve CO2. What does comparing their timescales tell you about how fast living things had to shift their ranges?
Modification for Distance Learning
Post each station as a slide in a shared deck. Groups add their energy budget sketch and prediction to the slide from a breakout room.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: Earth's Energy Budget as an In-Out Model
Global average flows, with arrow widths drawn to scale (0.12 px per W/m²). Of the 340 W/m² of sunlight arriving, 102 W/m² is reflected and 238 W/m² is absorbed. At balance, Earth sends the same 238 W/m² back to space as infrared. Each cause of climate change works by resizing one arrow.
Diagram 2: Causes of Climate Change by Timescale
The four timescale groups from the NGSS Clarification Statement on a logarithmic axis, where each grid line is ten times the one before. Ocean circulation appears in both of the two shortest groups.
04
Homework Assignment
~30 min
HS-ESS2-4 Homework: Using an Energy Budget Model
Directions: Use a solar constant of 1361 W/m², σ = 5.67 × 10-8 W/(m²·K4) and a present-day albedo of 0.30 unless a problem says otherwise. For sea level, use an ocean area of 3.61 × 1014 m², so about 362 gigatonnes (Gt) of melted land ice raise sea level by 1 mm. All data are invented or rounded. Show each calculation with units and end each problem with a sentence that uses the model.
Part 1: Calculating with the Model (Problems 1-2)
Suppose the Sun's output rose by 0.25% and stayed there. (a) By how many W/m² does the solar constant increase? (b) How much more energy does Earth absorb per square meter, averaged over the globe? (c) Estimate the change in the balance temperature. (d) Which arrow of the energy budget changed?
Absorbed sunlight stays at 238.2 W/m². Greenhouse gases lower the fraction of surface infrared that escapes, ε, from 0.611 to 0.598. (a) Find the outgoing infrared at a surface temperature of 288 K. (b) Find the imbalance and say whether Earth gains or loses energy. (c) Find the surface temperature at which the flows balance again. (d) Name two results from the Assessment Boundary list you would expect.
Part 2: Causes and Timescales (Problems 3-4)
Sort these six causes into the four timescale groups of Diagram 2, and name the arrow each one changes: (a) haze from a tropical eruption that lasts 3 years; (b) a 60-year rise in CO2 from burning coal and gas; (c) the 41,000-year swing in the tilt of Earth's axis; (d) 30 million years of slow CO2 removal by rock weathering; (e) a 2-year change in Pacific Ocean currents; (f) a 70-year period of slightly weaker solar output.
An invented record shows land ice losing 270 Gt per year for 10 years. (a) How much does sea level rise from this melt? (b) Melting ice takes 334 kJ per kilogram. How much energy per year went into melting the ice? (c) Explain how this energy connects to an imbalance in the energy budget.
Part 3: Modeling and Critiquing (Problems 5-6)
At 60°N, the noon Sun on the June solstice stands 90° - 60° + tilt above the horizon. (a) Find the Sun's height for a tilt of 22.1° and of 24.5°. (b) Compare the noon sunlight on level ground in the two cases, using sin(height). (c) Use the result to argue whether ice sheets near 60°N would grow or shrink at the larger tilt.
A student writes: "Carbon dioxide lets more sunlight in, so Earth warms." (a) Explain what is wrong with this model and redraw the energy budget correctly. (b) Air temperature on a mountain drops about 6.5 °C per kilometer of height. If the climate warms by 2 °C, about how far uphill would a plant need to move to stay at the same temperature? (c) Name one other result of the warming on precipitation patterns and explain it.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Using the Model
Names the arrow that changes and the direction of the imbalance for every cause
Names the arrow or the direction, but not both
Calculations
Correct energy, temperature, sea level or angle calculation with units
Correct method with one arithmetic or unit error
Timescales
Places each cause in the right timescale group and explains the choice
Most causes placed correctly, with no explanation
Results and Critique
Predicts results limited to temperature, precipitation, ice, sea level or living things, and names a model limit
Prediction is vague or no limit of the model is named
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Use a solar constant of 1361 W/m² and σ = 5.67 × 10-8 W/(m²·K4). All data are invented or rounded. Your score updates as you answer, and Reset quiz clears everything so you or your students can try again.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
In the energy budget model, what has to be true for Earth's average temperature to stay steady over many years?
Answer: B
A steady temperature means no net energy gain or loss, so absorbed sunlight must equal emitted infrared. Choice D describes an imbalance that makes Earth warm. Choice C confuses a steady temperature with a planet that has no greenhouse effect; Earth has been steady with greenhouse gases for long stretches.
Question 2 of 20 · Multiple Choice
Averaged over the globe, 340 W/m² of sunlight reaches Earth. If the albedo were 0.35 instead of 0.30, how much sunlight would Earth absorb?
Answer: D
Absorbed = 340 × (1 - 0.35) = 221 W/m². Choice A is the reflected part (340 × 0.35), not the absorbed part. Choice C uses the present-day albedo of 0.30, and choice B ignores reflection altogether.
Question 3 of 20 · Multiple Choice
An invented record shows the global average surface temperature dropping by 0.4 °C within one year, then returning to its old value over the next three years. Which cause best fits this pattern?
Answer: C
The change starts fast and is gone within a few years, which matches eruption haze: it stays in the upper atmosphere for one to a few years and reflects sunlight while it lasts. Choice A acts over about 100,000 years, and choice B over millions of years. Choice D is a geologic process that takes tens of millions of years, so none of them could reverse within three years.
Question 4 of 20 · Multiple Choice
Why can a large volcanic eruption cool Earth's surface for a year or two?
Answer: A
The main short-term effect is a higher albedo: tiny droplets of sulfuric acid reflect sunlight, so the absorbed arrow shrinks. Choice B would warm Earth, not cool it. Choice C reverses the effect of CO2, which strengthens the greenhouse effect. Choice D confuses Earth's reflectivity with the Sun's output.
Question 5 of 20 · Multiple Choice
In a model run, the amount of methane in the air doubles. Like CO2, methane absorbs infrared. What is the first change in the energy budget?
Answer: D
A gas that absorbs infrared shrinks the outgoing arrow, so absorbed sunlight is briefly larger than emitted infrared and Earth gains energy until the surface warms enough to restore the balance. Choices A and C describe the Sun, which a gas in Earth's air cannot change. Choice B is about the albedo arrow.
Question 6 of 20 · Multiple Choice
Suppose satellite data showed Earth absorbing 240.0 W/m² of sunlight and emitting 237.5 W/m² of infrared. What does the model predict?
Answer: A
The imbalance is 240.0 - 237.5 = +2.5 W/m², a net gain. As the surface warms, σT4 grows and the gap closes. Choice B reverses the sign. Choice D forgets that emission rises with temperature, which is what lets the system reach a new balance.
Question 7 of 20 · Multiple Choice
During a strong La Niña, cold water spreads across the surface of the tropical Pacific and the ocean takes up extra heat from the air. What does the model predict for the global average surface temperature that year?
Answer: B
La Niña is a change in ocean circulation that moves energy from the atmosphere into the ocean, so the air at the surface cools for about a year even though the energy stays inside Earth's systems. Choice C confuses moving energy within the system with losing it to space. Choice A looks at the ocean instead of the surface air, and choice D ignores the heat exchange.
Question 8 of 20 · Multiple Choice
Using 362 Gt of melted land ice for 1 mm of sea level rise, how much would sea level rise if 1,810 Gt of land ice melted?
Answer: B
1,810 ÷ 362 = 5 mm. Choice A and choice C are off by a factor of 10, a place-value slip. Choice D treats every gigatonne as one millimeter.
Question 9 of 20 · Multiple Choice
Over about 20,000 years, the tilt of Earth's axis decreases from 24.5° toward 22.1°. Which prediction follows from the energy model?
Answer: A
Less tilt puts the summer Sun lower over high latitudes, so summers there get less energy and some winter snow survives each year. Over thousands of years the snow builds ice sheets, and the water stored in them lowers sea level. Choice B overstates the change: tilt mostly moves sunlight between seasons and latitudes. Choice C reverses the geometry, and choice D reverses the link between cold oceans, ice and sea level.
Question 10 of 20 · Multiple Choice
If the Sun's output fell by 1%, by about how much would Earth's balance temperature (254.6 K) change?
Answer: C
Temperature goes as the fourth root of absorbed energy, so a 1% drop changes T by about 1% ÷ 4: 254.6 × (0.991/4 - 1) ≈ -0.64 K. Choice A takes 1% of 255 K and forgets the fourth root. Choice D has the wrong sign.
Question 11 of 20 · Multiple Choice
A student's model uses one average temperature for the whole planet. Which prediction can that model NOT make?
Answer: D
A one-number model has no geography, so it cannot place changes in precipitation patterns. It does handle the global questions in choices A, B and C. Naming this limit is part of using a model well.
Question 12 of 20 · Multiple Choice
Air temperature on a mountainside falls about 6.5 °C per kilometer of height. After 1.5 °C of warming, about how far uphill would a tree species need to shift to stay at the same temperature?
Answer: B
1.5 °C ÷ 6.5 °C per km ≈ 0.23 km, about 230 m. Choice C multiplies instead of dividing (1.5 × 6.5 = 9.75), and choice D divides the wrong way (6.5 ÷ 1.5).
Question 13 of 20 · Multiple Choice
Suppose that over 20 million years, faster volcanic outgassing raised CO2 from 400 to 1,200 ppm. Which result matches this change in the model?
Answer: A
Higher CO2 keeps a larger share of the surface's infrared from escaping, so Earth's balance temperature rises; ice sheets melt and the meltwater raises sea level. Choice D gives CO2 a role it does not have, since CO2 lets visible sunlight through. Choice C blames the Sun, which this scenario does not involve.
Question 14 of 20 · Multiple Choice
A large ice sheet spreads across a continent. How does the ice itself change the energy budget?
Answer: C
Ice and snow are bright, so a larger ice cover raises the albedo and shrinks the absorbed arrow, which cools the climate further. Choice B reverses the direction, and choice A confuses ice with a gas that absorbs infrared. Choice D misses that ice cover is one of the ways Earth's reflectivity changes.
Question 15 of 20 · Short Answer
Use the energy budget model to explain, step by step, how adding greenhouse gases leads to a warmer surface and then to a new steady temperature.
Greenhouse gases absorb infrared from the surface and send part of it back down, so less infrared escapes to space while the absorbed sunlight stays the same. Energy in is now larger than energy out, so the surface and oceans gain energy and warm. A warmer surface emits more (σT4), so the outgoing flow grows until it again equals the absorbed sunlight. At that point the temperature stops rising at a new, higher value.
Question 16 of 20 · Short Answer
Earth's albedo is 0.30 today. Find the absorbed sunlight and the balance temperature if the albedo were 0.25. Use a solar constant of 1361 W/m².
Absorbed = 1361 ÷ 4 × (1 - 0.25) = 255.2 W/m². Setting σT4 = 255.2 gives T = (255.2 ÷ 5.67 × 10-8)1/4 ≈ 259.0 K, about 4.4 K warmer than at albedo 0.30.
Question 17 of 20 · Short Answer
A classmate says, "Orbital changes are tiny, so they cannot cause ice ages." Use the ideas of timescale and energy flow to answer the classmate.
Orbital changes barely change the total sunlight Earth receives in a year, and they shift summer sunlight at high latitudes by only about a tenth or less, but they keep acting in the same direction for thousands of years. A small extra loss of summer melt, repeated every year for thousands of years, lets snow pile up into ice sheets. Growing ice then reflects more sunlight, which adds to the cooling. The size of a cause is not enough: how long it acts matters too.
Question 18 of 20 · Short Answer
Absorbed sunlight is 238.2 W/m². In a no-feedback model, the fraction of surface infrared that escapes falls to ε = 0.590. At what surface temperature do the flows balance again?
Solve ε σT4 = 238.2: T = (238.2 ÷ (0.590 × 5.67 × 10-8))1/4 ≈ 290.5 K, about 2.5 K warmer than 288 K.
Question 19 of 20 · Short Answer
An invented core record shows that a 3,000-year warm interval melted enough land ice to raise sea level by 6 m. Name two other results from the Assessment Boundary list you would look for in the record, and say what each would show.
Any two of: higher surface temperatures (for example, from isotope or pollen records); smaller glacial ice volume (ice sheet edges farther back); shifts in precipitation patterns (lake levels or dust records); changes in where living things lived (pollen of warm-climate plants farther toward the poles or higher up mountains). Each is a result of more energy staying in Earth's systems.
Question 20 of 20 · Short Answer
Two scientists argue. One says a single large eruption explains a 30-year warming trend. The other says it cannot. Use timescales from the model to decide who is right.
The second scientist is right. Eruption haze falls out of the atmosphere within a few years, so an eruption changes the reflected arrow for only 1-3 years and would cause cooling, not warming. A trend lasting 30 years needs a cause that keeps acting for decades, such as rising greenhouse gases.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does HS-ESS2-4 mean?
HS-ESS2-4 asks students to use a model of energy entering and leaving Earth's systems to explain how changes in those flows change climate. Students use the model rather than memorize causes: they say which flow a cause changes, whether Earth gains or loses energy, and what happens to temperature, rainfall, ice, sea level or living things. The code stands for High School, Earth and Space Science, core idea 2 (Earth's Systems), performance expectation 4.
Is HS-ESS2-4 taught in Earth science or environmental science?
It is usually taught in Earth and Space Science, and it also fits Environmental Science or the Earth unit of an integrated science course. Some schools pair it with the energy standards of physics. The math is ratios, percentages and a fourth root on a calculator.
What is the assessment boundary for HS-ESS2-4?
Results of climate change are limited to surface temperatures, precipitation patterns, glacial ice volumes, sea levels and biosphere distribution. Other effects, such as changes in ocean chemistry or economic impacts, are beyond this standard. The causes can come from any of the four timescales in the Clarification Statement.
What model do students use for this standard?
An energy budget: sunlight in, sunlight reflected and infrared emitted, often drawn as three arrows. Students can add numbers (340, 102 and 238 W/m² on a global average) and a temperature rule (σT4), or build a simple spreadsheet that steps the temperature forward year by year. The standard does not require one specific model, only that students use one to describe the effect of a change.
Why is the calculated temperature 255 K when Earth's surface is about 288 K?
The 255 K value is the temperature a planet with no greenhouse gases would need in order to emit what Earth absorbs. Greenhouse gases keep part of the surface's infrared from escaping, so the surface runs about 33 K warmer. This gap is a good starting point for the idea that changing greenhouse gases changes the outgoing arrow.
How can a volcano cool the climate if it also releases CO2?
Over a few years, the sulfate haze from a large eruption reflects sunlight and cools the surface; the CO2 from one eruption is small compared with what is already in the air. Over millions of years, the story changes: steady volcanic CO2 is one of the long-term controls on atmospheric composition. The two effects work on different timescales.
What are Milankovitch cycles?
They are slow, regular changes in Earth's orbit and axis: the shape of the orbit (about 100,000 and 400,000 years), the tilt of the axis (about 41,000 years) and the wobble of the axis (about 19,000-23,000 years). They change how sunlight is spread across seasons and latitudes, and they pace the ice ages of the last few million years. They are the 10-100s of thousands of years group in HS-ESS2-4.
Is the Sun causing today's warming?
No. Satellite measurements since the late 1970s show solar output rising and falling with the 11-year cycle but no upward trend, while global temperatures rose. A change in the incoming arrow cannot explain a warming trend when the incoming arrow has not grown. Rising greenhouse gases, which change the outgoing arrow, fit the data.
Do students need calculus or advanced physics for this lesson?
No. Every calculation on this page uses multiplication, division, percentages and a fourth root (two square roots in a row). The spreadsheet model uses a simple step rule instead of calculus. Students who have finished Algebra I can do all of it with a calculator.
What labs work safely for climate and energy models?
Lamp labs work well: black and white cards, cards at different angles, or jars under a lamp. Keep hot bulbs away from paper and hands, keep water off the lab table, and use alcohol-filled or digital thermometers, never mercury. Goggles protect against a bulb that breaks. Spreadsheet models need no lab safety at all and give quantitative results.
07
Related Standards
6 standards
These standards connect to HS-ESS2-4: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
MS-ESS2-6Prerequisite
Model how unequal heating and rotation drive circulation that sets regional climate
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