Human Impact on Climate Flashcards

Which human activity is the largest source of the excess carbon dioxide (CO₂) that is enhancing the greenhouse effect and causing recent climate change?

Answer: The burning of fossil fuels for electricity, heat, and transportation.

The combustion of fossil fuels (coal, oil, and natural gas) for energy is the single largest human-caused source of carbon dioxide emissions. This process releases vast amounts of carbon that were stored underground for millions of years, significantly increasing the concentration of CO₂ in the atmosphere.

A large area of rainforest is cleared and burned to make way for agriculture. Which of the following describes the most significant, direct impact of this action on the global climate?

Answer: A decrease in the Earth's capacity to absorb carbon dioxide from the atmosphere.

Forests, especially large rainforests, act as critical 'carbon sinks,' absorbing massive amounts of CO₂ from the atmosphere for photosynthesis. Deforestation not only releases the carbon stored in the trees back into the atmosphere but also permanently removes that area's ability to absorb CO₂, leading to a net increase in greenhouse gases.

The world's oceans absorb a significant amount of the carbon dioxide released into the atmosphere by human activities. Which of the following is a direct chemical consequence of this absorption?

Answer: Increased ocean acidity, which harms marine organisms with shells.

When excess carbon dioxide (CO₂) dissolves in seawater, it forms carbonic acid (H₂CO₃), which lowers the ocean's pH. This process, known as ocean acidification, reduces the availability of carbonate ions that marine organisms like corals, clams, and oysters need to build their shells and skeletons.

Scientists analyze air bubbles trapped deep within Antarctic ice cores. They find that over the past 800,000 years, atmospheric CO₂ levels and global temperatures have consistently risen and fallen together. What is the most logical conclusion that can be drawn from this strong correlation?

Answer: Atmospheric carbon dioxide concentration is a critical factor in regulating Earth's temperature.

The consistent, repeating pattern found in ice core data shows a strong coupling between atmospheric CO₂ and global temperature. While orbital cycles can initiate warming or cooling, the resulting change in CO₂ acts as a powerful feedback that amplifies the temperature change, demonstrating that CO₂ is a principal control knob for Earth's climate.

A state government offers incentives for power companies to close coal-fired power plants and build wind and solar farms instead. What is the primary climate-related benefit of this shift in energy production?

Answer: It reduces the emission of greenhouse gases that cause global warming.

The primary climate benefit of switching from fossil fuels like coal to renewable sources like wind and solar is the significant reduction in greenhouse gas emissions. Coal plants release large amounts of CO₂ during combustion, while wind and solar generate electricity with little to no direct emissions.

Besides carbon dioxide, methane (CH₄) is another powerful greenhouse gas. Which of the following human activities is a major source of atmospheric methane?

Answer: Livestock farming and the decomposition of waste in landfills.

Major human-related sources of methane include agriculture and waste management. Methane is produced by the digestive processes of livestock (like cattle) and is also released when organic matter decomposes in oxygen-poor environments, such as landfills.