Earth Systems
Which Earth sphere contains all living things?
Biosphere
What carbon-cycle process removes carbon dioxide from the atmosphere?
Phyotosynthesis
What do greenhouse gases do in Earth’s atmosphere?
They absorb and re-emit infrared radiation, reducing the rate at which heat escapes to space.
Carbon dioxide increases from 320 ppm to 350 ppm. How much has it increased?
30 ppm
Which source is generally more credible?
A. An anonymous social media post
B. A government science agency
C. An advertisement
D. An influencer’s video
B. A government science agency.
Rain falls from a cloud into a river. Which two Earth spheres are directly involved?
The atmosphere and hydrosphere.
A dead leaf is broken down by microorganisms. What carbon-cycle process is occurring?
Decomposition
True or false: The greenhouse effect is entirely caused by human activity.
Explain your decision.
False. The natural greenhouse effect keeps Earth warm enough for life. Human activities enhance it by increasing greenhouse gas concentrations.
Atmospheric carbon dioxide concentrations were:
1960: 315 ppm
1980: 339 ppm
2000: 370 ppm
2020: 414 ppm
Describe the overall trend, using data.
Atmospheric carbon dioxide concentration increased as time increased, rising from 315 ppm in 1960 to 414 ppm in 2020.
A website makes a climate claim but provides no author, evidence or references. Give two reasons why the information may not be credible.
The author’s expertise cannot be checked, and no evidence or references are provided to support the claim.
A plant absorbs carbon dioxide from the air during photosynthesis. Identify the two spheres interacting and state what is transferred.
The atmosphere and biosphere interact. Carbon in carbon dioxide is transferred from the atmosphere into the biosphere.
Classify each example as a carbon source or carbon sink:
1. Growing forest
2. Burning petrol
3. Photosynthesising algae
4. Bushfire
1. Sink
2. Source
3. Sink
4. Source
Place these events in the correct order:
1. Earth’s temperature increases.
2. Coal is burned.
3. More infrared radiation is absorbed and re-emitted in the atmosphere.
4. Atmospheric carbon dioxide increases
2, 4, 3, 1.
Carbon dioxide increased from 354 ppm to 414 ppm while the temperature anomaly increased overall from 0.45°C to 1.02°C. Describe the relationship between the variables using data.
There is an overall positive relationship. As carbon dioxide increased by 60 ppm, the temperature anomaly increased overall by 0.57°C.
Two researchers repeat an investigation using the same method and obtain very similar results. What does this suggest about the investigation?
The investigation appears reproducible, which increases confidence in the results.
Heavy rain soaks into soil and triggers a landslide. Explain the interaction between the hydrosphere and geosphere. Include what is transferred.
Water from the hydrosphere enters soil in the geosphere. The transfer of water increases the amount of water in the soil and can make the soil less stable, contributing to a landslide.
A tree absorbs carbon dioxide as it grows. Years later, the tree dies and decomposes. Explain how carbon moves between Earth’s spheres during both processes.
During photosynthesis, carbon moves from the atmosphere into the biosphere. During decomposition, carbon moves from the biosphere back into the atmosphere as carbon dioxide. Some carbon may also enter the geosphere as organic matter.
A city replaces some coal-generated electricity with solar electricity. Explain how this could reduce the city’s contribution to the enhanced greenhouse effect.
Solar panels generate electricity without burning fossil fuels during operation. This reduces carbon dioxide emissions, slowing the increase in atmospheric greenhouse gases and reducing the city’s contribution to the enhanced greenhouse effect.
Earth naturally has a greenhouse effect, yet scientists are concerned about the enhanced greenhouse effect. Explain the difference.
The natural greenhouse effect keeps Earth warm enough for life. The enhanced greenhouse effect occurs when increased greenhouse gas concentrations cause additional warming.
Source A is from a government research organisation, names the scientists, provides monitoring data and explains its method. Source B is a personal blog with no author qualifications, references or method. Which source is more credible? Justify your decision using two pieces of evidence.
Source A is more credible because it comes from a recognised scientific organisation and provides its data and method. This allows the evidence to be checked and the investigation to be reproduced.
A bushfire burns vegetation and releases smoke and carbon dioxide into the atmosphere. Explain two transfers of matter between Earth’s spheres that occur during or after the fire.
During combustion, carbon moves from the biosphere into the atmosphere as carbon dioxide. After the fire, carbon dioxide may move from the atmosphere back into the biosphere when plants photosynthesise. Ash may also move from the biosphere into the geosphere.
A forest is cleared and the trees are burned. Explain why this can increase atmospheric carbon dioxide in two different ways.
urning the trees releases stored carbon into the atmosphere as carbon dioxide. Clearing the forest also reduces photosynthesis, so less carbon dioxide is removed from the atmosphere in the future.
A student states, “Carbon dioxide is bad because Earth would not heat up without it.” Explain what is scientifically incorrect and provide a more accurate explanation.
Carbon dioxide is a naturally occurring greenhouse gas that contributes to the natural greenhouse effect, which keeps Earth warm enough for life. The concern is that human activities are increasing carbon dioxide concentrations and strengthening the greenhouse effect, contributing to global warming.
A student says, “The greenhouse effect is bad, so Earth would be better without greenhouse gases.” Evaluate the statement.
The statement is incorrect. The natural greenhouse effect is essential for maintaining temperatures suitable for life. The problem is the strengthening of the greenhouse effect due to increased greenhouse gas concentrations.
Thirty independent scientific teams using different methods find evidence that Earth’s average temperature is increasing. One study finds no increase. A student states, “Scientists disagree, so there is no scientific consensus.” Evaluate this claim.
The claim is not justified. Scientific consensus develops when a large body of independent, credible evidence supports the same explanation. One conflicting study should be evaluated, but it does not automatically outweigh the larger body of consistent evidence.