Objectives Explain the greenhouse effect. Describe global warming. Describe how humans impact...

ObjectivesExplain the greenhouse effect.

Describe global warming.

Describe how humans impact climate.

Impact of Human ActivitiesSection 14.4

Review Vocabulary

radiation: transfer of thermal energy by electromagnetic waves


Over time, human activities can alter atmospheric conditions enough to influence changes in weather and climate.

greenhouse effect global warming

New Vocabulary


Influence on the Atmosphere

The greenhouse effect

The process of absorption and radiation of energy in the atmosphere results in the greenhouse effect—the natural heating of Earth’s surface caused by certain atmospheric gases called greenhouse gases.


Influence on the Atmosphere

The greenhouse effect

An increase in the amount of atmospheric greenhouse gases, particularly carbon dioxide and methane, would theoretically result in increased absorption of energy in the atmosphere. This can lead to a rise in global temperatures, known as global warming.

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Global Warming


Temperatures worldwide have shown an upward trend over the past 200 years, with several of the warmest years on record having occurred within the last two decades.


Global Warming

Burning fossil fuels

One of the main sources of atmospheric carbon dioxide from humans is from the burning of fossil fuels including coal, oil, and natural gas. Burning fossil fuels also releases other greenhouse gases, such as methane and nitrous oxide, into the atmosphere.


Global Warming

Deforestation

Deforestation—the mass removal of trees—also plays a role in increasing levels of atmospheric carbon dioxide.

When trees are cut down, photosynthesis is reduced, and more carbon dioxide remains in the atmosphere.


Global Warming

Environmental efforts

Individuals can reduce the amount of carbon dioxide emitted to the atmosphere by conserving energy, which reduces fossil fuel consumption.

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Study Guide

Climate

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Over time, human activities can alter atmospheric conditions enough to influence changes in weather and climate.

The greenhouse effect influences Earth’s climate.

Worldwide temperatures have shown an upward trend over the past 200 years.

Section 14.4 Impact of Human Activities

Study Guide Key Concepts

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Human activities can influence changes in weather and climate.

Individuals can reduce their environmental impact on climate change.

Section 14.4 Impact of Human Activities

Study Guide Key Concepts

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14.4 Section Questions

Climate

Which gas is a greenhouse gas that is released when fossil fuels are burned?

a. oxygen

b. helium

c. carbon dioxide

d. nitrogen

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Climate

Which type of electromagnetic radiation is partly captured and reradiated by greenhouse gases in the atmosphere?

a. visible light

b. ultraviolet radiation

c. infrared radiation

d. gamma rays

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Climate

How can people reduce the amounts of greenhouse gases released into the atmosphere?

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Climate

Possible answer: One way to reduce the amounts of greenhouse gases is to conserve. If less energy from fossil fuels is used, less greenhouse gas will be released. A second way is to sequester, or capture and store, greenhouse gases. This method may be used more in the future than it is today. A third way is to increase the use of energy sources that do not release greenhouse gases.

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Climate

Why do many scientists think that increasing levels of greenhouse gases in the atmosphere are contributing to global warming?

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Answer: Earth receives solar energy from the Sun and then reradiates much of the energy as infrared radiation. Greenhouse gases in the atmosphere capture certain wavelengths of this radiation and then reradiate the heat energy back toward Earth. Increasing amounts of greenhouse gases result in increasing amounts of heat being held by the atmosphere.


Climate

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Which twenty-year period has the highest average global temperature?

a. 1880 to 1900

b. 1900 to 1920

c. 1960 to 1980

d. 1980 to 2000

Standardized Test Practice

Climate

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Section 14.4 Vocabulary

Climate

greenhouse effect global warming

Objectives Explain the greenhouse effect. Describe global warming. Describe how humans impact...

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