HS-ESS2-2NGSS*ScienceEarth and Space ScienceGrades 9-12
HS-ESS2-2: Analyzing Data on Feedbacks Among Earth's Systems
In plain English: HS-ESS2-2 is the NGSS high school performance expectation that asks students to analyze geoscience data to support the claim that one change to Earth's surface can set off feedbacks that change other Earth systems. A key example is ice-albedo feedback: melting ice exposes darker surfaces that absorb more sunlight and melt more ice. It is usually taught in Earth and Space Science.
Analyze geoscience data to make the claim that one change to Earth's surface can create feedbacks that cause changes to other Earth systems.
Clarification Statement: Examples should include climate feedbacks, such as how an increase in greenhouse gases causes a rise in global temperatures that melts glacial ice, which reduces the amount of sunlight reflected from Earth's surface, increasing surface temperatures and further reducing the amount of ice. Examples could also be taken from other system interactions, such as how the loss of ground vegetation causes an increase in water runoff and soil erosion; how dammed rivers increase groundwater recharge, decrease sediment transport, and increase coastal erosion; or how the loss of wetlands causes a decrease in local humidity that further reduces the wetland extent.
Next Generation Science Standards · Disciplinary Core Idea: Earth's Systems · Official standard
Students analyze geoscience data to support a claim that one change to Earth's surface can set off feedbacks that change other Earth systems (the geosphere, hydrosphere including ice, atmosphere and biosphere). They compute albedo and absorbed sunlight, read runoff, sediment, groundwater and humidity data, draw feedback loops, and decide whether each loop amplifies the first change or dampens it. The anchor case is the climate feedback named in the standard: warming melts ice, the darker surface reflects less sunlight, and the surface warms further.
The NGSS Clarification Statement says: "Examples should include climate feedbacks, such as how an increase in greenhouse gases causes a rise in global temperatures that melts glacial ice, which reduces the amount of sunlight reflected from Earth's surface, increasing surface temperatures and further reducing the amount of ice. Examples could also be taken from other system interactions, such as how the loss of ground vegetation causes an increase in water runoff and soil erosion; how dammed rivers increase groundwater recharge, decrease sediment transport, and increase coastal erosion; or how the loss of wetlands causes a decrease in local humidity that further reduces the wetland extent." There is no official Assessment Boundary for this performance expectation. Every data set on this page is invented for teaching, with realistic values; albedos are typical rounded values (sea ice 0.60, open ocean 0.06, fresh snow 0.80-0.85). Students do the practice of analyzing data: they calculate, compare, graph and write a claim with evidence and reasoning, and they ask whether the data show cause or only a pattern.
Learning Objectives
By the end of this lesson, students will be able to:
Compute albedo and absorbed sunlight, including an area-weighted albedo for a region with two kinds of surface
Analyze data tables on ice, vegetation, rivers and wetlands to identify how one surface change affects other Earth systems
Draw a feedback loop, name the Earth system at each step, and classify the loop as amplifying (positive) or stabilizing (negative)
Write a claim, evidence and reasoning statement that uses data to support the claim that a surface change creates feedbacks, and tell a pattern in data from evidence of cause
Prior Knowledge Required
Students should already be comfortable with:
The water cycle, driven by sunlight and gravity MS-ESS2-4
Questions and evidence about the rise in global temperatures over the past century MS-ESS3-5
Ask students to think about a sunny summer afternoon.
Warm-Up Prompt
"You can walk barefoot on light-colored sand or on dark pavement in the same sunshine. Which one is hotter, and why? Now picture a large patch of white sea ice melting into dark ocean water. Predict what happens next, and then what happens after that."
Record the chains of predictions students make ("the water gets warmer, so more ice melts"). Tell students that a chain that loops back to its start is called a feedback, and that today they will test such chains with data.
Direct Instruction15-20 minutes
Feedback loops and albedo. A feedback happens when a change in one part of the Earth system causes changes that come back and affect the first part. An amplifying (positive) feedback makes the first change larger; a stabilizing (negative) feedback makes it smaller. Albedo is the fraction of incoming sunlight a surface reflects: albedo = reflected ÷ incoming, so absorbed = (1 - albedo) × incoming. For a region with two surfaces, the albedo is the area-weighted average. One stabilizing example acts over hundreds of thousands of years: a warmer, wetter climate speeds up the chemical weathering of rock, which removes carbon dioxide from the air and cools the climate again. Walk through Diagram 1, then the examples. The incoming sunlight values are invented seasonal averages.
Climate feedback: sea ice against open ocean
Incoming summer sunlight averages 250 W/m² over an invented polar sea. Sea ice has an albedo of 0.60, and open ocean 0.06.
Result: Absorbed by ice = (1 - 0.60) × 250 = 100 W/m². Absorbed by ocean = (1 - 0.06) × 250 = 235 W/m², 2.35 times as much. Each square meter that melts absorbs more energy, which melts more ice: an amplifying feedback.
Climate feedback: a whole region
The same sea goes from 90% ice cover to 60% ice cover over several summers.
Result: Albedo = 0.06 + 0.54 × (ice fraction): 0.546 at 90% and 0.384 at 60%. Absorbed = 250 × (1 - albedo): 113.5 W/m² rising to 154 W/m², an increase of 40.5 W/m² (about 36%).
Loss of ground vegetation
Invented plot data from a hillside with 800 mm of rain a year: with 90% plant cover, 5% of the rain runs off and 0.2 t/ha of soil erodes; with 20% cover, 35% runs off and 6 t/ha erodes.
Result: Runoff = 0.05 × 800 = 40 mm against 0.35 × 800 = 280 mm, 7 times as much, and 30 times as much soil lost. Thinner soil holds less water and fewer seeds, so fewer plants return: an amplifying loop between the biosphere and the geosphere.
A dammed river
Invented averages before and after a dam: sediment reaching the coast drops from 30 to 6 million tonnes per year, the water table near the reservoir rises from 8.0 m to 5.0 m below the surface, and the shoreline changes from building out 1.0 m/yr to retreating 4.0 m/yr.
Result: Sediment falls by 24 ÷ 30 = 80%. Groundwater rises 3.0 m (more recharge). The coast swings by 5.0 m/yr, from growth to erosion. One change to a river reaches the groundwater near the dam, the sediment supply and the coastline far downstream.
After each example ask: "Which Earth systems changed? Does the chain loop back to the first change? Does it make that change larger or smaller?" Stress that a loop must be supported by data at each step, not only by a story.
Guided Practice15 minutes
Pairs analyze invented September data for one study region of a polar sea, with incoming sunlight 200 W/m², sea ice albedo 0.60 and ocean albedo 0.06. The temperature column is the change in average summer surface-air temperature compared with an earlier baseline.
Guided practice data (invented): one polar study region
Year
Ice fraction
Temperature change (°C)
1990
0.70
+0.2
2000
0.62
+0.6
2010
0.50
+1.1
2020
0.42
+1.6
Compute the region albedo for each year with albedo = 0.06 + 0.54 × ice fraction (1990: 0.438).
Compute absorbed sunlight = 200 × (1 - albedo) for each year (1990: 112.4 W/m²) and describe the trend.
Graph absorbed sunlight and temperature change against year. Do both rise together?
Write a claim with evidence. Then name one more measurement that would show the extra absorbed energy is causing more melting, not just happening at the same time.
Independent Practice10-15 minutes
Each student analyzes a new invented data set from a mountain valley where spring snow now melts earlier. Fresh snow has an albedo of 0.80 and bare ground 0.20, and incoming May sunlight averages 300 W/m².
Independent practice data (invented): a mountain valley
Decade
Date the valley floor is snow-free
Average May soil temperature (°C)
1980s
May 28
3.1
1990s
May 21
3.9
2000s
May 12
4.8
2010s
May 5
5.6
Students compute the absorbed sunlight on snow and on bare ground, find how many days earlier the valley became snow-free from the 1980s to the 2010s, draw the loop that links the two data columns, and write a claim with evidence and reasoning.
Closure5 minutes
Exit ticket: "A parking lot replaces a grass field, and rain now runs off into a stream. Name two Earth systems that change, and say whether you would need more data to call it a feedback." Collect and sort the answers for the next lesson.
Differentiation Strategies
For Struggling Students
Give a loop template with five empty boxes and arrows, and a word bank of the four Earth systems
Provide a worked row of each data table (albedo and absorbed sunlight already filled in) before students complete the rest
Use the claim frame: "The data show that when ___ changed, ___ also changed, which then ___ the first change."
For Advanced Students
Ask students to find, from the guided practice data, how much absorbed sunlight rises per 0.10 drop in ice fraction, and to explain why the relationship is a straight line
Have students look for a stabilizing feedback that could slow the ice-albedo loop and describe the data that would show it
Ask students to explain why data from one region cannot by themselves show a global feedback, and to plan what data they would add
Assessment Guidance
What to Look For
Check that students compute absorbed sunlight with (1 - albedo), not with the albedo itself, and that they weight a regional albedo by area. Look for loops in which every arrow is backed by a data column, and for correct use of amplifying and stabilizing (positive does not mean good). Listen for students who treat two trends rising together as proof of cause: ask what extra evidence would link them.
02
Classroom Activities
3 Activities
1
Albedo and Melting Lab
25 minPairs
Pairs test how surface color affects melting. They place identical ice cubes on a white paper square and a black paper square side by side under the same light, time how long each takes to melt, and read a thermometer tucked under each paper.
Procedure
Lay the two paper squares on a tray, 5 cm apart, and slide a thermometer under each. Record the starting temperatures.
Place the lamp so the bulb is about 30 cm above both squares, or set the tray in direct sunlight. Put one ice cube on each square.
Record the temperature under each square every 2 minutes and the time when each cube has fully melted.
Safety: the bulb gets hot, so do not touch it or move the lamp while it is on, and keep paper at least 30 cm from the bulb. Keep water and wet trays away from the lamp cord and outlet, and wipe spills at once.
Sample Data (invented)
Black square: the cube melted in 14 minutes, and the temperature under the paper rose from 22 °C to 34 °C. White square: the cube melted in 23 minutes, and the temperature rose from 22 °C to 27 °C.
Discussion Questions
How many minutes sooner did the cube on the black square melt, and how many degrees more did that square warm?
Which part of the lab stands for sea ice, and which stands for open ocean?
The lab shows one step of the loop. Design a change to the setup that would show the whole loop, where melting itself makes the surface darker.
Modification for Distance Learning
Students run the lab at home with a sunny windowsill, two paper squares and ice cubes, or analyze the sample data above and post their loop diagram.
2
Feedback Data Stations
25 minGroups of 3-4
Four stations each hold an invented data set about one change to Earth's surface. At each station, groups compute one change from the data, draw the loop with an Earth system in each box, and mark it amplifying or stabilizing. Groups rotate every 6 minutes.
Station Data (invented)
Station 1, a drained wetland: wetland area 50, 38 and 29 km², summer relative humidity 74%, 69% and 65%, and summer rainfall 210, 188 and 170 mm in three decades.
Station 2, thawing permafrost: the depth of soil that thaws each summer is 50, 56 and 63 cm, and carbon released from the soil is 40, 52 and 67 g per square meter per year in three decades.
Station 3, an overgrazed grassland: plant cover falls from 60% to 20% over ten years, while dust-storm days rise from 4 to 19 per year.
Station 4, a weathering experiment: crushed rock sits in water for one week at 10 °C and at 25 °C; the dissolved calcium is 2.0 mg/L and 4.5 mg/L. Dissolving this kind of rock uses up carbon dioxide.
Discussion Questions
Which stations show an amplifying loop, and which show a stabilizing one? Point to the data column behind each arrow.
Which station works on the longest time scale, and why does that matter for predicting climate over the next 50 years?
For Station 1, which Earth systems appear in the loop?
Modification for Distance Learning
Post each station as a slide with its table. Groups meet in breakout rooms and submit one loop diagram per station on a shared document.
3
Runoff Trays: Bare Soil Against Plant Cover
25 minGroups of 3-4
Groups compare two trays of the same soil, one bare and one covered with sod or grass seedlings, tilted at the same angle. They pour the same "rain" on each, then measure how much water runs off and how much soil it carries.
Procedure
Set both trays on two books with their low ends over collection containers.
Pour 1.0 L of water slowly and evenly over each tray from a watering can held 20 cm above the soil.
Measure the runoff volume. Let the sediment settle, pour off the clear water, dry the sediment on a paper towel and weigh it.
Safety: wear gloves or wash hands after handling soil, wipe up spills so no one slips, and keep electrical equipment away from the water.
Sample Data (invented)
Bare tray: 620 mL of runoff carrying 48 g of soil. Covered tray: 180 mL of runoff carrying 6 g of soil.
Discussion Questions
What percent of the water ran off each tray, and how many times as much soil did the bare tray lose?
Where did the rest of the water go on the covered tray, and which Earth system does that water join?
Use the data to explain how losing plant cover this year could make it harder for plants to grow back next year.
Challenge Variation
Add a third tray with half the surface covered, predict its runoff and soil loss from the first two trays, and test the prediction.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: The Ice-Albedo Feedback Loop
The climate feedback named in the standard. Warming melts sea ice, the darker open ocean reflects less sunlight, the ocean absorbs more energy, and the air and water warm further. Every arrow is "more leads to more", so the loop amplifies the first change. Each box names the Earth system that changes.
Diagram 2: Absorbed Sunlight Against Sea-Ice Cover
Absorbed sunlight for a region with incoming sunlight of 250 W/m², sea ice albedo 0.60 and open ocean albedo 0.06, drawn to scale. The two points are the worked example: dropping from 90% to 60% ice cover raises absorbed sunlight from 113.5 to 154 W/m².
04
Homework Assignment
~30 min
HS-ESS2-2 Homework: Finding Feedbacks in Earth Data
Directions: All data sets are invented for practice, with realistic values. Show each calculation. For every problem, name the Earth systems involved and end with a claim that cites specific numbers as evidence.
Part 1: Albedo and Climate Feedback (Problems 1-2)
In early spring, incoming sunlight on an invented tundra averages 180 W/m². Fresh snow has an albedo of 0.85, and bare tundra 0.20. (a) Find the absorbed sunlight for each surface. (b) How many times as much does bare tundra absorb? (c) Snow now melts two weeks earlier than it used to. Draw the loop that follows and say whether it is amplifying or stabilizing.
An invented mountain region has glacier ice (albedo 0.55) and bare rock (albedo 0.15). The fraction covered by ice was 0.45, 0.40, 0.33 and 0.28 in 1990, 2000, 2010 and 2020. (a) Compute the region albedo for each year. (b) With incoming sunlight of 230 W/m², compute the absorbed sunlight in 1990 and 2020. (c) Write a claim, with evidence, about how the glacier loss affects the energy the region absorbs.
Part 2: Vegetation and Rivers (Problems 3-4)
After a wildfire on an invented hillside, plant cover and sediment washed off were: before the fire, 85% cover and 0.5 t/ha per year; year 1 after, 15% and 12 t/ha; year 3 after, 50% and 3 t/ha. (a) How many times the pre-fire sediment loss was the year 1 loss? (b) What does the year 3 row show? (c) Describe the feedback between plants and soil, and the data that show it weakening as plants return.
An invented river delta's shoreline was 20 m and 10 m inland of its 1970 position in 1950 and 1960. A dam upstream was finished in 1970. The shoreline was then 35, 70 and 105 m inland of its 1970 position in 1980, 1990 and 2000. (a) Find the rate of shoreline change before and after the dam, with signs. (b) Explain, using sediment, why the change happened. (c) Wells near the reservoir now reach water 2 m higher. Predict one change to living things along the retreating coast (for example, in coastal marshes or on beaches where animals nest), and name the data you would collect to test your prediction.
Part 3: Wetlands and Loops (Problems 5-6)
An invented wetland had an area of 60, 52 and 45 km² in 1995, 2005 and 2015, while summer relative humidity was 76%, 71% and 67% and summer rain was 240, 221 and 203 mm. (a) Find the percent loss of wetland area from 1995 to 2015. (b) Draw the loop that links the three columns, and find the percent drop in summer rain from 1995 to 2015. (c) The data show a pattern, not proof of cause. Name one measurement that would test whether the smaller wetland caused the lower humidity.
Classify each loop as amplifying or stabilizing, and explain how you decided: (a) warmer ocean water can hold less dissolved carbon dioxide, so more of the gas stays in the air, which warms the ocean further; (b) a warmer surface gives off more infrared radiation to space, which cools the surface; (c) a mountain glacier shrinks, exposing dark rock that warms the air next to the ice that is left, which melts more of the glacier.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Data Analysis
Correct albedo, absorbed sunlight, rates and percent changes with units
Correct method with one calculation or unit error
Feedback Loops
Loops name an Earth system at each step and are correctly classified as amplifying or stabilizing
Loop drawn but a system is missing or the classification is wrong
Claim, Evidence, Reasoning
Claim cites specific numbers and explains how they show one change causing changes in other systems
Claim stated with general evidence, or pattern treated as proof of cause
05
Quiz: 20 Questions
Interactive, with answers
Instructions
All data sets are invented, with realistic values. Albedo = reflected ÷ incoming, and absorbed sunlight = (1 - albedo) × incoming. 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
Which statement describes an amplifying (positive) feedback?
Answer: B
An amplifying feedback loops back and strengthens the first change. Choice A describes a stabilizing (negative) feedback. Choice D confuses "positive" with "good": positive only means the loop pushes in the same direction.
Question 2 of 20 · Multiple Choice
A surface receives 240 W/m² of sunlight and reflects 72 W/m². What is its albedo?
Answer: D
Albedo = reflected ÷ incoming = 72 ÷ 240 = 0.30. Choice A is the fraction absorbed (1 - 0.30). Choice B divides incoming by reflected. Choice C writes the reflected value as a decimal without dividing.
Question 3 of 20 · Multiple Choice
Incoming sunlight is 320 W/m² on a forest with an albedo of 0.15. How much sunlight does the forest absorb?
Answer: A
Absorbed = (1 - 0.15) × 320 = 272 W/m². Choice B is the reflected part (0.15 × 320). Choice C subtracts 15 instead of 15%. Choice D ignores reflection.
Question 4 of 20 · Multiple Choice
A region is 40% snow (albedo 0.80) and 60% forest (albedo 0.10). What is the region albedo?
Answer: B
Weight each albedo by its area: 0.40 × 0.80 + 0.60 × 0.10 = 0.32 + 0.06 = 0.38. Choice A is a plain average that ignores the areas. Choice C swaps the weights. Choice D adds the two albedos.
Question 5 of 20 · Multiple Choice
Which change to a surface would reduce the amount of sunlight it reflects?
Answer: C
Dark soil has a lower albedo than snow, so it reflects less and absorbs more. Choices A, B and D all replace a darker surface with a brighter one, which raises the albedo.
Question 6 of 20 · Multiple Choice
Invented hillside plots have plant cover of 80%, 50% and 20%, with runoff of 8%, 19% and 33% of rainfall. Which claim do the data support?
Answer: D
As cover drops from 80% to 20%, runoff rises from 8% to 33%. Choice B reverses the trend. Choice C is not supported: the first 30-point drop in cover adds 11 points of runoff and the second adds 14.
Question 7 of 20 · Multiple Choice
A dam traps sediment behind it. Which result downstream do the data in this lesson lead you to expect at the coast?
Answer: A
Waves keep removing sand from the coast, and with the sediment supply cut the coast loses more than it gains, so it retreats. Choice C ignores that the river links the dam to the coast. Choice D confuses a local shoreline change with a change in sea level.
Question 8 of 20 · Multiple Choice
A wetland shrinks, local humidity falls, less rain falls and the wetland shrinks further. What kind of feedback is this?
Answer: C
The first change (a smaller wetland) leads back to more of the same change, so the loop amplifies it. Choices A and D mix up the direction of a quantity with the effect of the loop. Choice B misses that a feedback can pass through several Earth systems.
Question 9 of 20 · Multiple Choice
Which is an example of a stabilizing (negative) feedback?
Answer: B
Faster plant growth removes some of the added carbon dioxide, which works against the first change. Choices A, C and D each make the first change larger, so they are amplifying loops.
Question 10 of 20 · Multiple Choice
Incoming sunlight is 300 W/m², sea ice albedo is 0.60 and ocean albedo is 0.06. By how much does absorbed sunlight rise when the ice fraction of the region drops by 0.10?
Answer: C
The region albedo falls by 0.10 × (0.60 - 0.06) = 0.054, so absorbed sunlight rises by 0.054 × 300 = 16.2 W/m². Choice A slips a factor of 10. Choice B uses 0.10 × 300 and ignores the albedo difference. Choice D multiplies the albedo difference by 100 instead of by the sunlight.
Question 11 of 20 · Multiple Choice
Data from one sea show that ice cover fell while summer temperatures rose. Which added evidence best supports the claim that less ice is causing extra warming?
Answer: D
The claimed mechanism is that open water absorbs more sunlight, so a direct measurement of more absorbed sunlight where ice disappeared links the two trends. Choices A and B are not about the mechanism. Choice C only repeats that ice declined.
Question 12 of 20 · Multiple Choice
An invented field gets 600 mm of rain in a year, and 30% of it runs off. How much water runs off?
Answer: C
0.30 × 600 = 180 mm. Choice A is the part that does not run off. Choice B divides 600 by 30. Choice D slips a factor of 10.
Question 13 of 20 · Multiple Choice
Sediment carried by a river to the sea fell from 50 to 15 million tonnes per year after a dam was built. What is the percent decrease?
Answer: A
The drop is 50 - 15 = 35 million tonnes, and 35 ÷ 50 = 70%. Choice B is the percent that still arrives. Choice C gives the drop in tonnes as a percent. Choice D divides by the new value instead of the original.
Question 14 of 20 · Multiple Choice
After a dam is built, groundwater near the reservoir rises and the coast downstream erodes. Which Earth systems does the dam change in this case?
Answer: B
Groundwater belongs to the hydrosphere, and sediment and the coastline belong to the geosphere. Choice D is wrong because human-made changes to the surface still act on natural systems. Choices A and C each name a system not shown by these data.
Question 15 of 20 · Short Answer
Incoming sunlight is 220 W/m². Find the sunlight absorbed by sea ice with an albedo of 0.65 and by open ocean with an albedo of 0.07. Use your numbers to explain why melting speeds up once it starts.
Ice: (1 - 0.65) × 220 = 77 W/m². Ocean: (1 - 0.07) × 220 = 204.6 W/m², about 2.7 times as much. Each patch of ice that melts turns into water that absorbs much more energy, which warms the water and melts nearby ice: an amplifying feedback.
Question 16 of 20 · Short Answer
A region with incoming sunlight of 280 W/m² goes from 75% to 55% sea ice cover. With sea ice albedo 0.60 and ocean albedo 0.06, find the region albedo before and after and the change in absorbed sunlight.
Albedo = 0.06 + 0.54 × fraction: 0.465 before and 0.357 after. Absorbed = 280 × (1 - albedo): 149.8 W/m² before and 180.04 W/m² after, a rise of about 30.2 W/m².
Question 17 of 20 · Short Answer
Draw or describe the feedback loop that starts when overgrazing strips the plants from a dry grassland. Name the Earth system at each step and classify the loop.
Plants removed (biosphere) → bare, dry soil is exposed (geosphere) → wind lifts the loose soil as dust (atmosphere), and rain runs off instead of soaking in (hydrosphere) → topsoil, stored water and seeds are lost (geosphere) → fewer plants grow back (biosphere). Each step makes the first change larger, so the loop is amplifying. Rubric: 1 point for a closed loop, 1 for correct systems, 1 for the classification.
Question 18 of 20 · Short Answer
Invented data for a river: after a dam, sediment reaching the coast fell from 18 to 4.5 million tonnes per year, the beach narrowed from 60 m to 35 m in 10 years, and well water near the reservoir rose 2 m. Write a claim, evidence and reasoning statement.
Claim: the dam changed the geosphere and the hydrosphere downstream and around it. Evidence: sediment fell by 13.5 ÷ 18 = 75%, the beach narrowed by 2.5 m/yr, and groundwater rose 2 m. Reasoning: the reservoir traps sediment that used to rebuild the beach while waves keep removing sand, and water seeping from the reservoir recharges the groundwater.
Question 19 of 20 · Short Answer
A student says: "When sea ice melts, the Arctic will cool down, because melting ice absorbs heat." Use albedo data to evaluate the claim.
Melting does take in energy while it happens, but the claim leaves out what comes next. Once the ice is gone, the open ocean has an albedo near 0.06 instead of about 0.60 for sea ice, so it absorbs far more sunlight (for example 235 instead of 100 W/m² with 250 W/m² incoming). The region therefore absorbs more energy and warms, so the claim is not supported.
Question 20 of 20 · Short Answer
Plan an investigation with the ice-cube lab to test whether surface color changes how fast ice melts. Name the independent variable, the dependent variable, two controlled variables and one safety step.
Independent variable: surface color (for example white, gray and black paper). Dependent variable: time for the ice to melt (or temperature under the paper). Controlled: same cube size, same distance from the light, same room temperature, same paper size. Safety: do not touch the hot bulb, and keep water away from the lamp cord. Repeat each color at least three times.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does HS-ESS2-2 mean?
HS-ESS2-2 asks students to analyze geoscience data to support the claim that one change to Earth's surface can cause feedbacks that change other Earth systems. Students read data on ice, vegetation, rivers or wetlands and trace how a change in one system loops through others. The code means High School, Earth and Space Science, core idea 2 (Earth's Systems), performance expectation 2.
Is HS-ESS2-2 about climate change?
Partly. The Clarification Statement says examples should include climate feedbacks, such as melting ice reducing the sunlight Earth reflects. It also names other examples that are not about global climate: vegetation loss and erosion, dams and coastal erosion, and wetland loss and humidity.
Does HS-ESS2-2 have an assessment boundary?
No. NGSS lists no Assessment Boundary for HS-ESS2-2. The Clarification Statement guides the examples, and the focus stays on analyzing data about feedbacks among Earth systems.
What is a feedback loop in Earth science?
A feedback loop is a chain of cause and effect that comes back to its starting point. A change in one part of the Earth system causes changes elsewhere that then strengthen or weaken the first change. Loops often pass through several systems, such as the atmosphere, the ice and the ocean.
What is the difference between positive and negative feedback?
A positive (amplifying) feedback makes the first change larger; a negative (stabilizing) feedback makes it smaller. The words describe direction, not value: a positive feedback is not good, and a negative one is not bad. The ice-albedo loop is amplifying.
What is albedo, and how do you calculate it?
Albedo is the fraction of incoming sunlight a surface reflects: reflected ÷ incoming. Fresh snow reflects most sunlight (albedo around 0.8-0.9), while open ocean reflects very little (around 0.06). The absorbed part is (1 - albedo) × incoming. For a region with mixed surfaces, weight each albedo by its share of the area.
What are the four Earth systems?
The geosphere (rock, soil and sediment), the hydrosphere (water, including ice), the atmosphere (air) and the biosphere (living things). Some courses call ice the cryosphere. A feedback in HS-ESS2-2 links a change in one of them to changes in others.
How can students analyze feedback data without field equipment?
Use data tables and graphs from invented or published data sets, plus simple labs: ice cubes melting on light and dark paper model albedo, and trays of bare and planted soil model runoff and erosion. The practice is the same: calculate, compare, draw the loop and write a claim backed by the numbers.
Why do two trends in the same data not prove a feedback?
Two quantities can change together for another reason, such as a third factor driving both. To support a feedback, students need data for each link in the loop, for example that thawing soil releases more carbon dioxide and methane, and that the added gas traps more heat. Asking "what would show the mechanism?" is part of the practice.
What comes after HS-ESS2-2?
HS-ESS2-4 models how changes in energy flow into and out of Earth systems change climate, and HS-ESS3-5 uses data and climate model results to forecast future change. HS-ESS3-6 builds computational representations of how Earth systems and human activity affect each other.
07
Related Standards
6 standards
These standards connect to HS-ESS2-2: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
MS-ESS2-4Prerequisite
Model the cycling of water through Earth's systems, driven by sunlight and gravity
NGSS is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.
