Chapter 23: Problem 7

What are the possible causes of long-term climatic change?

Short Answer

Expert verified

Possible causes of long-term climatic change include 1) plate tectonics, which can alter land and ocean distribution, 2) changes in Earth's orbit and axial tilt, known as Milankovitch cycles, which can affect the distribution of solar radiation, 3) variations in solar output, which can alter the overall solar radiation reaching Earth, 4) large-scale volcanic activity, which can inject aerosols and gases into the atmosphere affecting global temperatures, and 5) changes in atmospheric composition, caused by natural processes and human activities, influencing the greenhouse effect and global climate.

Step by step solution

1. Plate Tectonics

Plate tectonics refers to the movement of Earth's lithosphere, which is divided into several plates that float on the mantle. The movement and interaction of these plates can lead to changes in the distribution of land and ocean, which in turn influence climate. For example, the formation of large continental landmasses can lead to increased glaciation and changes in atmospheric circulation patterns.

2. Changes in Earth's Orbit and Axial Tilt

The Earth's orbit around the Sun is not perfectly circular, and its axial tilt changes over time. These changes, known as Milankovitch cycles, can cause variations in the amount and distribution of solar radiation that reaches Earth, leading to long-term climate change. For example, more extreme axial tilt can result in greater seasonal temperature differences, while a more elliptical orbit can lead to longer, more intense winters.

3. Solar Output Variations

The Sun's energy output is not constant and undergoes slight variations over time. These variations in solar output, often called solar cycles, can contribute to long-term climate changes by altering the overall amount of solar radiation that reaches Earth. For example, a period of decreased solar output can lead to a cooler global climate.

4. Volcanic Activity

Large-scale volcanic eruptions can inject significant amounts of aerosols and gases into the atmosphere, which can influence global climate. Specifically, these aerosols can block or reflect sunlight, leading to a cooling effect. Although individual volcanic eruptions may only have a short-term impact on climate, sustained volcanic activity or clusters of large eruptions can lead to longer-term changes in global temperatures.

5. Changes in Atmospheric Composition

The composition of the Earth's atmosphere can significantly influence global climate. For example, increasing levels of greenhouse gases such as carbon dioxide, methane, and nitrous oxide can trap more heat in the atmosphere, leading to global warming. Conversely, decreasing levels of greenhouse gases can result in a cooling effect. Changes in atmospheric composition can occur due to various factors, including natural processes (e.g., volcanic eruptions) and human activities (e.g., fossil fuel combustion).

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What are the possible causes of long-term climatic change?

Short Answer

Step by step solution

1. Plate Tectonics

2. Changes in Earth's Orbit and Axial Tilt

3. Solar Output Variations

4. Volcanic Activity

5. Changes in Atmospheric Composition

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