Chapter 7 - Humans & Global Change

Shari and her family change their use of transportation. They use their private automobile less often, and instead rely more on public transportation, bicycles, and walking. How does their change in behavior affect their ecological footprint?

• The footprint decreases, because the family uses fewer energy resources and reduces their emissions of greenhouse gases.
• The footprint decreases, because the family travels across a smaller area of land.
• The footprint increases, because vehicles such as buses and subways use more energy than a private automobile.
• The footprint is not affected, because the family’s use of resources is approximately the same as before.

Which of the following increases the amount of carbon in the atmosphere? Select all that apply.

• acid rain
• deforestation
• invasive species
• burning fossil fuels

A scientist uses a computer model to predict that Earth’s average temperature will increase between 1.8°C and 3.2°C by the year 2100. The precise increase in temperature depends on people’s decisions in the future. Which event of the near future would increase the likelihood of the LOWEST possible temperature increase?

• Global emissions of greenhouse gases decrease by 50 percent.
• A major volcanic eruption strikes somewhere on Earth.
• New technology reduces consumer prices for coal, oil, and natural gas.
• Global emissions of chlorofluocarbons (CFCs) decrease by 50 percent.

Human activities have caused both acid rain and a global increase in temperature, or global warming. How are these two effects—acid rain and global warming—related to each other?

• Acid rain is a side effect of global warming at the local level.
• Acid rain is a side effect of efforts to reduce global warming.
• Both acid rain and global warming are caused by the burning of fossil fuels.
• Both acid rain and global warming are caused by increased levels of carbon dioxide in the atmosphere.

Juanita claims that cattle ranching contributes more significantly to global climate change than most other forms of agriculture. Clayton doubts this claim because carbon dioxide is released by all animals, not just cows. Which observation MOST STRONGLY supports Juanita’s claim?

• A cow is an especially large animal, and so it releases more carbon dioxide than a typical animal.
• A cow is raised for food for humans, and so it does not decompose as many wild animals do.
• A cow releases large amounts of methane, an especially potent greenhouse gas.
• A cow eats large amounts of grass, which help remove greenhouse gases through photosynthesis.

A population of timberwolves lives in a large tract of forest. A developer proposes building a six-lane highway across the middle of the forest. The developer claims that the timberwolves would be minimally affected because the highway would replace only about 1 percent of the land of the forest. Which statement provides the strongest argument AGAINST the developer’s claim?

• Wolves hunt across large territories, so habitat fragmentation puts them at risk.
• Wolves have been observed roaming the land where the highway would be.
• At least one wolf has built a den in the land where the highway would be.
• Deer, rabbits, and other prey of wolves have been observed roaming the land where the highway would be.

Johan claims that ozone is one of the harmful components of smog, that it is the result of human activity, and that it harms human health. Based on these claims, he argues that the use of chlorofluocarbons (CFCs) should be encouraged, because CFCs help break up ozone. Which is the most accurate evaluation of Johan’s claim and argument?

• The claims are accurate and the argument is supported by evidence.
• The claims are accurate, but the argument is faulty because ozone in the upper atmosphere protects life on the surface.
• The claims are inaccurate and the argument is faulty, because ozone is essential for human health.
• The claims are inaccurate because ozone is a natural part of the atmosphere, but the argument is supported by evidence.

Scientists cite evidence that anthropogenic (human-caused) emissions of carbon dioxide are causing Earth’s average temperatures to increase on a global scale. Which of the following changes to Earth’s systems are a direct or indirect result of the carbon dioxide emissions? Select four correct answers.

• rising sea levels
• ocean acidification
• increased frequency of volcanic eruptions
• changes to ecosystems and ecosystem services
• reduced ice coverage in polar ice caps and glaciers

Brian is evaluating the following statement. “The expression global warming is only a partial description of the changes occurring to Earth's atmosphere. Global climate change is the more accurate description.” Which observation provides the strongest evidence in support of the statement?

• Precipitation patterns are changing on a global scale.
• Sea level is rising because of melting polar ice caps.
• Coral reefs are dying or stressed because of warmer seawater.
• Carbon dioxide levels have been increasing globally for the past 150 years.

An organization of climate scientists reached an agreement on global climate change. They agree that the problem is serious and that a variety of measures should be enacted worldwide. The measures include a global reduction in greenhouse gas emissions and a switch to renewable energy resources. What is the effect, in practice, of the agreement of the scientists?

• The agreement dictates the laws of world governments, which have no right to alter the laws.
• The agreement forms the basis of laws enacted by world governments, which always include scientific oversight.
• The agreement may help guide world governments but does not force their actions.
• The agreement supersedes the actions of world governments because of the importance of global climate change.