Oceans, Carbon & Climate — Chapter Practice, Grade 9

Connect climate evidence with ocean circulation, carbon budgets, and Earth-system feedbacks.

Problem 1

Which statement correctly describes the difference between weather and climate?
  1. Weather is day-to-day conditions; climate is the long-term average pattern.
  2. Weather and climate mean the same thing.
  3. Climate changes every hour; weather stays the same for decades.
  4. Weather only applies to storms; climate applies to sunny days.
Answer and explanation

Weather is day-to-day conditions; climate is the long-term average pattern.

Weather is short-term (today's conditions); climate is the long-term average over decades.

Problem 2

Which of these gases is a greenhouse gas?
  1. Carbon dioxide
  2. Nitrogen
  3. Oxygen
  4. Argon
Answer and explanation

Carbon dioxide

Carbon dioxide absorbs and re-emits outgoing heat; nitrogen, oxygen, and argon make up most of the atmosphere but are not significant greenhouse gases.

Problem 3

Which factor would most directly give a region cooler average temperatures?
  1. Higher elevation
  2. Being closer to the equator
  3. Being farther from any ocean
  4. Having more greenhouse gases nearby
Answer and explanation

Higher elevation

Temperatures generally drop as elevation increases, since higher places have thinner air that holds less heat.

Problem 4

What keeps Earth's average surface temperature from being far below freezing?
  1. The natural greenhouse effect trapping some outgoing heat
  2. The ozone layer blocking all sunlight
  3. Ocean currents alone
  4. Earth's rotation
Answer and explanation

The natural greenhouse effect trapping some outgoing heat

The natural greenhouse effect traps enough outgoing heat to keep Earth's surface livable; without it, Earth would be far colder.

Problem 5

What is the key difference between the natural greenhouse effect and the human-caused concern often called global warming?
  1. The greenhouse effect itself is natural and necessary; the concern is that human activity is increasing greenhouse gas concentrations, enhancing the effect and raising temperatures further.
  2. There is no difference; they are the same process.
  3. The greenhouse effect only happens at the poles.
  4. Global warming is caused by too much oxygen in the atmosphere.
Answer and explanation

The greenhouse effect itself is natural and necessary; the concern is that human activity is increasing greenhouse gas concentrations, enhancing the effect and raising temperatures further.

The natural greenhouse effect keeps Earth livable. The concern is that burning fossil fuels and other activities have added extra greenhouse gases, intensifying the natural effect and pushing global average temperatures higher.

Problem 6

A classmate says, 'The greenhouse effect is bad and we should get rid of it completely.' Explain what's scientifically incorrect about that statement.
Answer and explanation

The greenhouse effect itself is natural and necessary — without it, Earth would be far too cold to support life as we know it. The real problem is that human activities have increased the amount of greenhouse gases in the atmosphere, enhancing the natural effect beyond its normal balance and causing global temperatures to rise; the goal is to reduce that extra human-caused increase, not eliminate the greenhouse effect altogether.

Problem 7

A region has one unusually cold winter within a 30-year warming record. Are those facts contradictory? Explain the reasoning in your own words.
Answer and explanation

No; the full record, variability and spatial coverage are needed.

Weather varies from year to year.

A long-term trend summarizes many measurements, so an individual cold period can coexist with warming.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 8

Why is a snowy surface's albedo relevant to climate? Show the reasoning, not just the conclusion.
Hints

Do not confuse greenhouse warming with an ozone hole.

Answer and explanation

A higher albedo reflects a larger fraction of sunlight, reducing absorbed solar energy under otherwise similar conditions.

Problem 9

What would distinguish climate evidence from one day's temperature?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Long-term, representative records and distributions, ideally multiple independent indicators.

Problem 10

A feedback loop must return to the initial changeA feedback loop must return to the initial changeWarmersurfaceLess icecoverMore solarabsorptionIce–albedo feedback returns to the initial changePositive feedback amplifies; the word does not mean beneficial.
Original conceptual ice–albedo loop with selected linked mechanisms. The diagram does not supply feedback strength, equilibrium change or regional forecast. It omits other feedbacks and conditions that can oppose or modify the response.
Interpret the supplied visual model. Why is “warming reduces ice” alone not a complete feedback explanation?
Answer and explanation

It gives one response. To complete the feedback, explain how changed ice alters absorbed energy and feeds back onto the initial warming.

Trace the loop back to warmer surface. A one-way arrow from temperature to ice would show a response but omit the feedback’s return effect.

It gives one response. To complete the feedback, explain how changed ice alters absorbed energy and feeds back onto the initial warming.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 11

A future graph shows a +2 °C regional anomaly in one scenario. Explain what “anomaly” and “scenario” require, and why one cold local day does not directly test that projected regional long-term mean.
Answer and explanation

An anomaly is relative to a specified baseline; a scenario states assumptions about future inputs/decisions. The projected variable, region and interval must be given. A single local day is a different scale/measurement from a regional long-term mean and is not a direct matched test.

An anomaly is relative to a specified baseline; a scenario states assumptions about future inputs/decisions. The projected variable, region and interval must be given. A single local day is a different scale/measurement from a regional long-term mean and is not a direct matched test.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 12

Surface ocean currents are driven largely by…
  1. winds
  2. the Moon’s light
  3. continental color
  4. fossil ages
Answer and explanation

winds

Wind transfers momentum to the ocean surface.

Problem 13

How can fresh water at the surface affect density?
Answer and explanation

It can lower salinity and density relative to otherwise comparable seawater, affecting stratification.

Problem 14

Why do coastal climates often have smaller temperature swings than inland climates?
Answer and explanation

The ocean stores and releases substantial energy and influences nearby air temperatures.

Problem 15

Two nearby coastal areas at similar latitude have different winter temperatures. Explain one ocean-related possibility. Explain the reasoning in your own words.
Answer and explanation

Different currents and heat exchange may contribute; wind and geography must also be examined.

Different currents can bring water with different thermal histories.

Ocean heat storage and air–sea energy transfer can affect the coastal air.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 16

Why do ocean currents influence coastal climate? Show the reasoning, not just the conclusion.
Hints

Compare combined effects; salinity and temperature may oppose each other.

Answer and explanation

They redistribute heat, affecting air temperatures and other regional conditions.

Problem 17

Can warmer but much saltier water always be ranked against colder fresher water without data?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

No. Both properties affect density; quantitative conditions are needed to determine the net comparison.

Problem 18

An overturning loop summarizes a system with many pathwaysAn overturning loop summarizes a system with many pathwaysSelected surface and deeper pathwaysMixing / exchangeReal overturning has branches, multiple basins and unequal time scales.
Original qualitative overturning and exchange schematic. Red and blue distinguish selected warmer-surface and deeper pathways; they do not supply actual temperatures. The figure omits geographic detail and quantified flows and explicitly marks a mixing path outside the simple loop.
Interpret the supplied visual model. What information does a single conveyor loop omit that would matter for a real carbon or heat transfer estimate?
Answer and explanation

Branch pathways, basin geometry, transport rates, mixing and residence/travel times, plus changing conditions. A loop picture alone cannot quantify the transfer.

Trace the main arrows and the extra mixing link. These are selected paths, not a promise that each water parcel follows the whole loop at one fixed speed.

Branch pathways, basin geometry, transport rates, mixing and residence/travel times, plus changing conditions. A loop picture alone cannot quantify the transfer.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 19

At comparable pressure, measured densities of two ocean-water samples are 1026 and 1023 kg/m³. Which has greater density, and why would a colder-temperature label alone be insufficient to explain the difference or full circulation?
Answer and explanation

The 1026 kg/m³ sample is denser. Salinity, pressure and combined conditions influence density; circulation also depends on surrounding stratification, forcing, boundaries and mixing. Temperature alone does not establish a complete mechanism or forecast.

The 1026 kg/m³ sample is denser. Salinity, pressure and combined conditions influence density; circulation also depends on surrounding stratification, forcing, boundaries and mixing. Temperature alone does not establish a complete mechanism or forecast.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 20

Inputs are 15 carbon units/year and outputs are 11. Find storage change.
Answer and explanation

4 carbon units/year

15 − 11 = 4.

Problem 21

An amplifying feedback…
  1. opposes every change
  2. increases the effect of an initial change
  3. is always good
  4. contains no causal links
Answer and explanation

increases the effect of an initial change

It reinforces the initial change.

Problem 22

Distinguish a carbon reservoir from a flux.
Answer and explanation

A reservoir is an amount stored; a flux is a transfer rate per time.

Problem 23

Warming reduces ice cover; darker surfaces absorb more sunlight. Identify the feedback and mechanism. Explain the reasoning in your own words.
Answer and explanation

A positive feedback through changing albedo.

Initial warming reduces reflective ice.

More absorption can reinforce the initial warming.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 24

A reservoir gains 8 units/year and loses 5. Find net annual change. Show the reasoning, not just the conclusion.
Hints

Positive refers to amplification, not a beneficial effect.

Answer and explanation

+3 units/year, assuming these are its only flows.

Problem 25

Give a condition needed before calling an observed link a feedback.
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

The response must loop back to influence the original change; correlation alone does not establish that causal loop.

Problem 26

Acidification describes a pH decrease, not necessarily pH below sevenAcidification describes a pH decrease, not necessarily pH below sevenSupplied pH7.888.20123Relative dissolved-CO₂ addition (model index)A fall in pH is acidification even when pH remains above 7.
Original qualitative supplied pH trend against a model addition index. It is not an observed seawater titration or a calibrated CO₂-to-pH relationship. The graph illustrates terminology and avoids implying a universal linear ocean-chemistry response.
Interpret the supplied visual model. Can a change from pH 8.2 to 8.0 be described as acidification while the water remains above pH 7?
Answer and explanation

Yes. The pH decreased. Acidification concerns that change, while above/below seven is a separate reference comparison under relevant conditions.

Compare the starting and ending pH while noting that every value shown remains above seven. The horizontal index is deliberately not a measured concentration.

Yes. The pH decreased. Acidification concerns that change, while above/below seven is a separate reference comparison under relevant conditions.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 27

A model store begins at 80 carbon units. Annual input is 6 and net uptake is 4 for five years. Find final storage. Would cutting input to 5 reverse the trend if uptake remains 4?
Answer and explanation

It gains 2 units/year, or 10 in five years, ending at 90. Cutting input to 5 gives +1 unit/year, so the store still rises more slowly; it does not decline under those assumptions.

Compute net 6−4 = 2 units/year.

Multiply by five and add to 80 to get 90.

Recalculate 5−4 = +1 and distinguish a smaller increase from a decline.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 28

A mean is 12.4°C and its baseline is 12.0°C. Find the anomaly.
Answer and explanation

0.4 °C

12.4 − 12.0 = 0.4.

Problem 29

A cold week disproves a multi-decade warming trend.
  1. True
  2. False
Answer and explanation

False

Short-term variability and long-term trends describe different scales.

Problem 30

Why state an emissions scenario with a projection?
Answer and explanation

The projected outcome depends partly on assumptions about future emissions.

Problem 31

An annual temperature is 14°C; baseline A is 12°C and B is 13°C. Find both anomalies. Explain the reasoning in your own words.
Answer and explanation

+2°C relative to A and +1°C relative to B; the actual temperature is unchanged.

Subtract each reference from the measurement.

14−12=+2°C; 14−13=+1°C.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 32

A dataset reports 0.3°C per decade. What does that unit mean? Show the reasoning, not just the conclusion.
Hints

Distinguish endpoint change from a fitted trend and attribution.

Answer and explanation

Average change of 0.3°C per 10 years under the stated trend estimate, not exactly that change every year.

Problem 33

Why compare observations with models that include and exclude different drivers?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

The comparison helps test whether proposed drivers reproduce the pattern, rather than inferring cause from a trend alone.

Problem 34

Read an actual global temperature-analysis recordRead an actual global temperature-analysis recordGlobal annual anomaly (°C; 1951–1980 baseline)-0.200.40.81.21970198019902000201020202025YearNASA GISS/GISTEMP v4 • complete selected annual entries 1970–2024
Original plot of actual NASA GISTEMP v4 annual global Land–Ocean estimates, all 55 selected years from 1970–2024. Anomalies in °C relative to 1951–1980; record accessed 2026-10-13. Citation: GISTEMP Team (2026) and Lenssen et al. (2024). Later years are outside this selected interval, and the graph alone does not establish causal attribution. NASA GISS/GISTEMP v4 — source and analysis · Lenssen et al. (2024) — observational uncertainty
Interpret the supplied visual model. What does the 2024 value 1.28 °C mean, and does this graph say every place was exactly 1.28 °C warmer?
Answer and explanation

It is the estimated global annual Land–Ocean anomaly of +1.28 °C relative to the 1951–1980 baseline in this accessed record. Regional and daily changes vary; it is not the same increase everywhere.

Read the actual annual points and their stated baseline. The plot’s upper values are anomalies, not Earth’s absolute surface temperature.

It is the estimated global annual Land–Ocean anomaly of +1.28 °C relative to the 1951–1980 baseline in this accessed record. Regional and daily changes vary; it is not the same increase everywhere.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 35

An observed annual temperature is 16.4 °C and its matched baseline is 15.8 °C. Find the anomaly. A separate future scenario curve gives +1.2 °C at year 20. Explain what must be supplied before comparing the values.
Answer and explanation

The observed anomaly is +0.6 °C. The projection must specify the same variable, region, baseline and averaging interval, plus its scenario/assumptions. An observation and a conditional future model remain different kinds of evidence.

Subtract 16.4−15.8 = +0.6 °C.

Check matching baseline, coverage and time definition.

Identify projection assumptions and distinguish modeled future values from observations.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 36

Read an actual global temperature-analysis recordRead an actual global temperature-analysis recordGlobal annual anomaly (°C; 1951–1980 baseline)-0.200.40.81.21970198019902000201020202025YearNASA GISS/GISTEMP v4 • complete selected annual entries 1970–2024
Original plot of actual NASA GISTEMP v4 annual global Land–Ocean estimates, all 55 selected years from 1970–2024. Anomalies in °C relative to 1951–1980; record accessed 2026-10-13. Citation: GISTEMP Team (2026) and Lenssen et al. (2024). Later years are outside this selected interval, and the graph alone does not establish causal attribution. NASA GISS/GISTEMP v4 — source and analysis · Lenssen et al. (2024) — observational uncertainty
The complete selected NASA annual record has anomalies +0.03 °C in 1970 and +1.28 °C in 2024, on the same 1951–1980 reference. Find the endpoint change. Explain why this two-value subtraction is neither a fitted trend rate nor proof that every year and place warmed by that amount. Use the complete selected table to find a pair of consecutive years with a decrease.
Answer and explanation

The endpoint change is 1.28−0.03 = +1.25 °C in the global annual Land–Ocean anomaly. The common reference cancels. A fitted rate needs a specified method across the record and time units; this subtraction is an endpoint change. One adjacent decrease is 1970 (+0.03 °C) to 1971 (-0.08 °C), a change of -0.11 °C. Local/daily changes differ from the global annual estimate, and the graph alone is not a complete causal attribution.

Use the same variable, reference and annual definition for both values.

Subtract 1.28−0.03 = +1.25 °C; describe it as an endpoint change across the selected interval.

Inspect adjacent entries in the complete table to show annual variation.

Distinguish a global annual statistical estimate from local conditions, a fitted rate and a causal analysis.

Response criteria

  • Calculate +1.25 °C with the correct endpoint and baseline interpretation.
  • Give a valid adjacent-year decrease from the supplied table.
  • Distinguish endpoint change, fitted rate, local variation and causal attribution.

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