Read the Following Scenario and Answer the Question Below

question 38

Multiple Choice

Read the following scenario and answer the question below.
Many geologists have proposed naming the current time period of Earth's history the Anthropocene epoch. The rationale for doing so includes the fact that erosion rates and greenhouse gas levels in the atmosphere have increased rapidly over the past 300 years. Almost all environmental scientists agree that increases in greenhouse gases contribute to global climate change. Carbon dioxide, methane, nitrous oxide, ozone, hydrochlorofluorocarbons, and water vapor are the main culprits. Human activities, chief among them the tapping and burning of fossil fuels for energy, have significantly increased these "greenhouse gases" in our atmosphere in the last 300 years. With rising standards of living in developing countries, emissions of carbon dioxide and other greenhouse gases are expected to continue to rise. If unchecked, carbon dioxide levels will reach twice preindustrial levels by midcentury and double again by the end of the century. Computer models have shown that this rise alone could raise Earth's temperatures by 3 to 10 degrees Fahrenheit by 2100.
-Positive feedback loops destabilize environmental systems by creating a "snowball effect," whereby a change in the system causes further change. Which of the following represents a positive feedback loop in regard to global warming?

• A)warming of Earth, increasing the evaporation of surface water
• B)controlling development, resulting in higher population densities in urban centers
• C)reforestation, causing a release of carbon dioxide from soil microbes
• D)limiting use of fossil fuels as a source of energy
• E)sequestering carbon dioxide underground, resulting in a drop in atmospheric carbon dioxide levels

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Definitions:

Carbon Fixation Reactions

Reduction reactions of photosynthesis in which carbon from carbon dioxide becomes incorporated into organic molecules, leading to the production of carbohydrate. See Calvin Cycle.

Reduced

A term often used in chemistry to describe the gain of electrons or decrease in oxidation state by a molecule, atom, or ion.

Oxidized

Describes a process where an atom, molecule, or ion loses electrons, often associated with a gain of oxygen or loss of hydrogen in chemical reactions.

Photophosphorylation

The production of ATP in photosynthesis.